Title of Invention: Methods of treatment using exendin peptides or GLP-1 peptides Abstract: Methods for increasing urine flow are disclosed, comprising administration of an effective amount of GLP-1, an exendin, or an exendin or GLP-1 agonist. Methods for increasing urinary sodium excretion and decreasing urinary potassium concentration are also disclosed. The methods are useful for treating conditions or disorders associated with toxic hypervolemia, such as renal failure, congestive heart failure, nephrotic syndrome, cirrhosis, pulmonary edema, and hypertension. The present invention also relates to methods for inducing an inotropic response comprising administration of an effective amount of GLP-1, an exendin, or an exendin or GLP-1 agonist. These methods are useful for treating conditions or disorders that can be alleviated by an increase in cardiac contractility such as congestive heart failure. Pharmaceutical compositions for use in the methods of the invention are also disclosed. Detailed Description: Part general_description_paragraphs: Part RELATED APPLICATIONS: This application is a continuation of U.S. application Ser. No. 10/656,093 filed Sep. 5, 2003, which is a divisional of U.S. application Ser. No. 09/622,105 filed Sep. 22, 2000, issued as U.S. Pat. No. 6,703,359, which is a §371 of PCT/US99/02554 filed Feb. 5, 1999, which claims the benefit of U.S. Provisional Application No. 60/075,122 filed Feb. 13, 1998. All applications are incorporated herein by reference. Part FIELD OF THE INVENTION: The present invention relates to methods for increasing urine flow comprising administration of an effective amount of glucagon-like peptide-1 [7-36] amide (abbreviated “GLP-[7-36]NH2” or simply “GLP-1”), an exendin, or an exendin or GLP-1 agonist. Methods for increasing urinary sodium excretion and decreasing urinary potassium concentration are also disclosed. The methods are useful for treating conditions or disorders associated with toxic hypervolemia, such as renal failure, congestive heart failure, nephrotic syndrome, cirrhosis, pulmonary edema, and hypertension. Pharmaceutical compositions for use in the methods of the invention are also disclosed. The present invention also relates to methods for inducing an inotropic response comprising administration of an effective amount of an exendin, GLP-1, or an exendin or GLP-1 agonist. These methods are useful for treating conditions or disorders that can be alleviated by an increase in cardiac contractility, such as congestive heart failure. The following description summarizes information relevant to the present invention. It is not an admission that any of the information provided herein is prior art to the presently claimed invention, nor that any of the publications specifically or implicitly referenced are prior art to that invention. Glucagon-like peptide-1 [7-36] amide (also referred to as GLP-1 [7-36]NH2 or GLP-1) is a product of the proglucagon gene. It is secreted into plasma mainly from the gut and produces a variety of biological effects related to pancreatic and gastrointestinal function. The parent peptide, proglucagon (PG), has numerous cleavage sites that produce other peptide products dependent on the tissue of origin including glucagon (PG[32-62]) and GLP-1[7-36]NH2 (PG[72-107]) in the pancreas, and GLP-1[7-37] (PG[78-108]) and GLP-1[7-36]NH2 (PG [78-107]) in the L cells of the intestine where GLP-1[7-36]NH2 (78-107 PG) is the major product. GLP-1[7-36]NH2, also known as proglucagon [78-107], or commonly, just “GLP-1,” as used herein, has an insulinotropic effect, stimulating insulin secretion from pancreatic β-cells; GLP-1 also inhibits glucagon secretion from pancreatic α-cells (Orskov, et al., Diabetes, 42:658-61, 1993; D'Alessio, et al., J. Clin. Invest., 97:133-38, 1996). GLP-1 is reported to inhibit gastric emptying (Williams B, et al., J Clin Endocrinol Metab 81 (1): 327-32, 1996; Wettergren A, et al., Dig Dis Sci 38 (4): 665-73, 1993), and gastric acid secretion. (Schjoldager B T, et al., Dig Dis Sci 34 (5): 703-8, 1989; O'Halloran D J, et al., J Endocrinol 126 (1): 169-73, 1990; Wettergren A, et al., Dig Dis Sci 38 (4): 665-73, 1993). A diuretic, antidypsogenic effect of intracerebroventricular administration of GLP-1 has been reported, however, this report claims that a peripheral, intraperitoneal injection of GLP-1 did not have this effect. (Tand-Christensen et al., Am. J. Physiol., 271:R848-56, 1996). GLP-1[7-37], which has an additional glycine residue at its carboxy terminus, also stimulates insulin secretion in humans (Orskov, et al., Diabetes, 42:658-61, 1993). A transmembrane G-protein adenylate-cyclase-coupled receptor believed to be responsible for the insulinotropic effect of GLP-1 has been cloned from a β-cell line (Thorens, Proc. Natl. Acad. Sci., USA 89:8641-45, 1992). Glucagon and glucagon-like peptides have been found to have different cardiovascular effects. Glucagon has been reported to have positive inotropic and chronotropic effects, produce a slight increase in arterial blood pressure in normal individuals, and affect regional blood circulation. GLP-1 has been found to produce a moderate increase in both systolic and diastolic blood pressure, while GLP-2 has no effect on those parameters. GLP-1, administered through the jugular vein, has been reported to induce an increase in systolic and diastolic blood pressure and heart rate. (Reviewed in Barragán, J. M., et al., Regul. Peptides, 67:63-68, 1996). Exendins are peptides that are found in the venom of the Gila-monster, a lizard endogenous to Arizona, and the Mexican Beaded Lizard. Exendin-3 is present in the venom of Heloderma horridum, and exendin-4 is present in the venom of Heloderma suspectum (Eng, J., et al., J. Biol. Chem., 265:20259-62, 1990; Eng., J., et al., J. Biol. Chem., 267:7402-05, 1992). The exendins have some sequence similarity to several members of the glucagon-like peptide family, with the highest homology, 53%, being to GLP-1 (Goke, et al., J. Biol. Chem., 268:19650-55, 1993). Exendin-4 is a potent agonist at GLP-1 receptors on insulin-secreting βTC1 cells, at dispersed acinar cells from guinea pig pancreas, and at parietal cells from stomach; the peptide also stimulates somatostatin release and inhibits gastrin release in isolated stomachs (Goke, et al., J. Biol. Chem. 268:19650-55, 1993; Schepp, et al., Eur. J. Pharmacol., 69:183-91, 1994; Eissele, et al., Life Sci., 55:629-34, 1994). Exendin-3 and exendin-4 were found to be GLP-1 agonists in stimulating cAMP production in, and amylase release from, pancreatic acinar cells (Malhotra, R., et al., Regulatory Peptides, 41:149-56, 1992; Raufman, et al., J. Biol. Chem. 267:21432-37, 1992; Singh, et al., Regul. Pept. 53:47-59, 1994). The use of the insulinotropic activities of exendin-3 and exendin-4 for the treatment of diabetes mellitus and the prevention of hyperglycemia has been proposed (Eng, U.S. Pat. No. 5,424,286). Truncated exendin peptides such as exendin[9-39], a carboxyamidated molecule, and fragments 3-39 through 9-39 have been reported to be potent and selective antagonists of GLP-1 (Goke, et al., J. Biol. Chem., 268:19650-55, 1993; Raufman, J. P., et al., J. Biol. Chem. 266:2897-902, 1991; Schepp, W., et al., Eur. J. Pharm. 269:183-91, 1994; Montrose-Rafizadeh, et al., Diabetes, 45 (Suppl. 2):152A, 1996). Exendin[9-39] blocks endogenous GLP-1 in vivo, resulting in reduced insulin secretion. Wang, et al., J. Clin. Invest., 95:417-21, 1995; D'Alessio, et al., J. Clin. Invest., 97:133-38, 1996). The receptor apparently responsible for the insulinotropic effect of GLP-1 has been cloned from rat pancreatic islet cells (Thorens, B., Proc. Natl. Acad. Sci. USA 89:8641-8645, 1992). Exendins and exendin[9-39] bind to the cloned GLP-1 receptor (rat pancreatic β-cell GLP-1 receptor: Fehmann H C, et al., Peptides 15 (3): 453-6, 1994; human GLP-1 receptor: Thorens B, et al., Diabetes 42 (11): 1678-82, 1993). In cells transfected with the cloned GLP-1 receptor, exendin-4 is an agonist, i.e., it increases cAMP, while exendin[9-39] is an antagonist, i.e., it blocks the stimulatory actions of exendin-4 and GLP-1. Id. Exendin[9-39] also acts as an antagonist of the full length exendins, inhibiting stimulation of pancreatic acinar cells by exendin-3 and exendin-4 (Raufman, et al., J. Biol. Chem. 266:2897-902, 1991; Raufman, et al., J. Biol. Chem., 266:21432-37, 1992). Exendin[9-39] inhibits the stimulation of plasma insulin levels by exendin-4, and inhibits the somatostatin release-stimulating and gastrin release-inhibiting activities of exendin-4 and GLP-1 (Kolligs, F., et al., Diabetes, 44:16-19, 1995; Eissele, et al., Life Sciences, 55:629-34, 1994). Exendin-4, administered through the jugular vein, has been reported to induce an increase in systolic, diastolic and mean arterial blood pressure, and in heart rate (Barragán, et al., Regul. Pep. 67:63-68, 1996). Exendins have recently been found to inhibit gastric emptying (U.S. patent application Ser. No. 08/694,954, filed Aug. 8, 1996, which enjoys common ownership with the present invention and is hereby incorporated by reference). Exendin[9-39] has been used to investigate the physiological relevance of central GLP-1 in control of food intake (Turton, M. D. et al., Nature, 379:69-72, 1996). GLP-1 administered by intracerebroventricular (ICV) injection inhibits food intake in rats. This satiety-inducing effect of GLP-1 delivered by intracerebroventricular injection is reported to be inhibited by ICV injection of exendin[9-39] (Turton, supra). However, it has been reported that GLP-1 does not inhibit food intake in mice when administered by peripheral injection (Turton, M. D., Nature 379:69-72, 1996; Bhavsar, S. P., Soc. Neurosci. Abstr. 21:460 (188.8), 1995). Administration of exendins and exendin agonists has also recently been found to reduce food intake (U.S. Provisional Patent Application Ser. No. 60/034,905, filed Jan. 7, 1997, which enjoys common ownership with the present invention and is hereby incorporated by reference). Agents that increase urine flow, or diuretics, are useful for treating conditions or disorders that are associated with toxic hypervolemic states. Such conditions or disorders include renal failure, congestive heart failure, nephrotic syndrome, cirrhosis, pulmonary edema, and hypertension. Diuretics are also employed to treat conditions in pregnancy, such as pre-eclampsia and eclampsia. Further uses of diuretics include their use to reduce volume before some surgical procedures such as ocular surgery and neurosurgery. One difficulty encountered with many diuretics such as thiazides, loop diuretics, carbonic anhydrase inhibitors, and osmotic diuretics, is that although they may be employed to increase sodium excretion, they also result in an increase of urinary potassium loss. Examples of the effects of potassium loss include muscular weakness, paralysis (including the paralysis of respiratory muscles), electrocardiographic abnormalities, cardiac dysrhythmia, and cardiac arrest. Another difficulty encountered with some diuretics is their slow rate of action, which is not conducive to their use in an emergency setting. Thus, there is a need for a method of increasing urine flow that does not deplete potassium concentration in the patient and which has a rapid mode of action. Such methods, and compounds and compositions which are useful therefore, have been invented and are described and claimed herein. Compounds that induce inotropic effects (e.g., increase of force of contraction of the heart) have been recognized as being useful for the treatment of, for example, congestive heart failure. Congestive heart failure, which is one of the most common causes of death and disability in industrialized nations, has a mortality rate of about 50% at five years (Goodman and Gilman's The Pharmacological Basis of Therapeutics, 9th Ed. McGraw Hill, New York, pp. 809-838). Inotropic agents currently in clinical use include digitalis, sympathomimetic amines and amrinone (Harrison's Principles of Internal Medicine, 12th Edition, 1991, McGraw Hill, New York, pp. 894-899). Digotoxin, a cardiac glycoside, an ancient but effective therapy for cardiac failure, was initially derived from the foxglove leaf, Digitalis purpurea and Digitalis lanata. Cardiac glycosides are potent and highly selective inhibitors of the active transport of sodium and potassium ions across cell membranes (Goodman and Gilman, supra). Cardiac glycosides have been reported to increase the velocity of shortening of cardiac muscle, resulting in an improvement in ventricular function; this effect has been reported to be due to an increase in the availability during systole of cytosolic Ca2+ to interact with contractile proteins to increase the velocity and extent of sarcomere shortening (Goodman and Gilman, supra). Digotoxin and related cardiac glycosides (e.g. digitoxin) have useful durations of action because their excretion, mainly via the kidneys, results in plasma t½ of 1.5-5 days. But the therapeutic index of these drugs is very low with mildly toxic:minimally-effective dose ratio being 2:1 and lethal:minimally-effective dose ratio being between 5:1 and 10:1. Urinary potassium loss due to use of thiazide and loop diuretics may seriously enhance the dangers of digitalis intoxication, including susceptibility to cardiac arrhythmia, and potassium-sparing diuretics are often necessary. Slow elimination of cardiac glycosides can prolong the period of jeopardy during digitalis intoxication, which has been reported to occur in 20% of hospital patients on these drugs. Absorption and onset of action for all cardiac glycosides except ouabain is somewhat prolonged, and this may be a disadvantage in emergency cardiac conditions. Sympathomimetic amines, which generally include epinephrine, isoproterenol, dopamine and dobutamine, can be useful in an acute setting to stimulate myocardial contractility, but they usually require constant intravenous infusion and continuous intensive monitoring of the patient. They typically lose their effectiveness after 8 hours, apparently due to receptor downregulation. Amrinone, a noncatecholamine, non-glycoside agent also requires continuous intravenous administration. This description of available inotropic agents illustrates the need for, and desirability of, therapies that are (1) inotropic, with (2) rapid onset of action, with (3) prolonged duration of action (including a persistent effect, with absence of tachyphylaxis), with (4) low toxicity (a high ratio of toxic to therapeutic dose), with (5) rapid and profound diuretic effect, with (6) a sparing of urinary potassium loss, and with (7) a convenient (non-intravenous) route of administration. We have discovered that exendin and GLP-1 fulfill these criteria. Part SUMMARY OF THE INVENTION: The present invention concerns the surprising discovery that exendins, GLP-1, and agonists of these compounds have rapid inotropic and diuretic effects. Although GLP-1 has been reported to not have a diuretic effect when administered peripherally, we have found, surprisingly, that GLP-1 does in fact have a diuretic effect after peripheral administration. This diuretic effect of exendins, GLP-1, and exendin and GLP-1 agonists, is accompanied by an increase in urinary sodium concentration. This diuretic effect is also accompanied by a decrease in urinary potassium concentration which is unanticipated as many diuretics have been found to cause a profound increase in urinary potassium concentration. The present invention is directed to novel methods for increasing urine flow comprising the administration of an exendin, for example, exendin-3 [SEQ ID NO. 1: His Ser Asp Gly Thr Phe Thr Ser Asp Leu Ser Lys Gln Met Glu Glu Glu Ala Val Arg Leu Phe Ile Glu Trp Leu Lys Asn Gly Gly Pro Ser Ser Gly Ala Pro Pro Pro Ser-NH2], or exendin-4 [SEQ ID NO. 2: His Gly Glu Gly Thr Phe Thr Ser Asp Leu Ser Lys Gln Met Glu Glu Glu Ala Val Arg Leu Phe Ile Glu Trp Leu Lys Asn Gly Gly Pro Ser Ser Gly Ala Pro Pro Pro Ser-NH2], or other compounds which effectively bind to the receptor at which exendin exerts its action on increasing urine flow (exendin agonists). The present invention is also directed to novel methods for increasing urine flow comprising the administration of GLP-1 [SEQ ID NO. 3: His Ala Glu Gly Thr Phe Thr Ser Asp Val Ser Ser Tyr Leu Glu Gly Gln Ala Ala Lys Glu Phe Ile Ala Trp Leu Val Lys Gly Arg-NH2], or other compounds which effectively bind to the receptor at which GLP-1 exerts its action on increasing urine flow (GLP-1 agonists). In a first aspect, the invention features a method of increasing urine flow in an individual comprising administering to the individual a therapeutically effective amount of an exendin or an exendin agonist. In one preferred aspect, said exendin is exendin-3. More preferably, said exendin is exendin-4. By an “exendin agonist” is meant a compound that mimics the effects of exendin on increasing urine flow, increasing sodium excretion, and/or decreasing urinary potassium concentration, (the potassium concentration in excreted urine) by binding to the receptor or receptors where exendin causes this effect. Certain novel exendin agonist compounds are described in U.S. Provisional Patent Application Ser. No. 60/055,404, filed Aug. 8, 1997, which was filed as PCT/98/16387, on Aug. 6, 1998 and nationalized as U.S. patent application Ser. No. 10/181,102, on Jul. 11, 2001 and enjoys common ownership with the present invention and is hereby incorporated by this reference. Certain other novel exendin agonist compounds are described in U.S. Provisional Patent Application Ser. Nos. 60/066,029 and 60/065,442, both filed Nov. 14, 1997, which were filed as PCT/US98/24210, on Nov. 13, 1998 and nationalized as U.S. patent application Ser. No. 09/554,531, on Aug. 8, 2000, and as PCT/US98/24273 on Nov. 13, 1998 and nationalized as U.S. patent application Ser. No. 09/554,533, on May 11, 2000, respectively, and enjoy common ownership with the present invention and are hereby incorporated by this reference. Preferred exendin agonist compounds include those described in U.S. Provisional Patent Application Ser. Nos. 60/055,404 and 60/065,442. In one preferred aspect the exendin or exendin agonist used in the methods of the present invention is exendin-4. In another preferred aspect, the exendin is exendin-3. In other preferred aspects, the exendin or exendin agonist is a compound of the formula (I) [SEQ ID NO. 4]: Xaa1 Xaa2 Xaa3 Gly Xaa5 Xaa6 Xaa7 Xaa8 Xaa9 Xaa10 Xaa11 Xaa12 Xaa13 Xaa14 Xaa15 Xaa16 Xaa17 Ala Xaa19 Xaa20 Xaa21 Xaa22 Xaa23 Xaa24 Xaa25 Xaa26 Xaa27 Xaa28-Z1; wherein Xaa1 is His, Arg or Tyr; Xaa2 is Ser, Gly, Ala or Thr; Xaa3 is Asp or Glu; Xaa5 is Ala or Thr; Xaa6 is Ala, Phe, Tyr or naphthylalanine; Xaa7 is Thr or Ser; Xaa8 is Ala, Ser or Thr; Xaa9 is Asp or Glu; Xaa10 is Ala, Leu, Ile, Val, pentylglycine or Met; Xaa11 is Ala or Ser; Xaa12 is Ala or Lys; Xaa13 is Ala or Gln; Xaa14 is Ala, Leu, Ile, pentylglycine, Val or Met; Xaa15 is Ala or Glu; Xaa16 is Ala or Glu; Xaa17 is Ala or Glu; Xaa19 is Ala or Val; Xaa20 is Ala or Arg; Xaa21 is Ala or Leu; Xaa22 is Phe, Tyr or naphthylalanine; Xaa23 is Ile, Val, Leu, pentylglycine, tert-butylglycine or Met; Xaa24 is Ala, Glu or Asp; Xaa25 is Ala, Trp, Phe, Tyr or naphthylalanine; Xaa26 is Ala or Leu; Xaa27 is Ala or Lys; Xaa28 is Ala or Asn; Z1 is —OH, —NH2, Gly-Z2, Gly Gly-Z2, Gly Gly Xaa31-Z2, Gly Gly Xaa31 Ser-Z2, Gly Gly Xaa31 Ser Ser-Z2, Gly Gly Xaa31 Ser Ser Gly-Z2, Gly Gly Xaa31 Ser Ser Gly Ala-Z2, Gly Gly Xaa31 Ser Ser Gly Ala Xaa36-Z2, Gly Gly Xaa31 Ser Ser Gly Ala Xaa36 Xaa37-Z2, Gly Gly Xaa31 Ser Ser Gly Ala Xaa36 Xaa37 Xaa38-Z2, or Gly Gly Xaa31 Ser Ser Gly Ala Xaa36 Xaa37 Xaa38 Xaa39-Z2; wherein Xaa31, Xaa36, Xaa37 and Xaa38 are independently selected from the group consisting of Pro, homoproline, 3Hyp, 4Hyp, thioproline, N-alkylglycine, N-alkylpentylglycine and N-alkylalanine; Xaa39 is Ser, Thr or Tyr; and Z2 is —OH or —NH2; and pharmaceutically acceptable salts thereof; provided that no more than three of Xaa3, Xaa5, Xaa6, Xaa8, Xaa10, Xaa11, Xaa12, Xaa13, Xaa14, Xaa15, Xaa16, Xaa17, Xaa19, Xaa20, Xaa21, Xaa24, Xaa25, Xaa26, Xaa27, and Xaa28 are Ala; and provided also that the compound is not exendin-3 [SEQ ID NO. 1] or exendin-4 [SEQ ID NO. 2]. In other aspects of the invention, the increase in urine flow is accompanied by an increase in sodium excretion in said individual. In most preferred aspects, the increase in urine flow does not increase urinary potassium concentration in said individual. In other embodiments of the invention, a method is provided for decreasing the concentration of potassium in the urine of an individual comprising administering to said individual a therapeutically effective amount of an exendin or an exendin agonist. In yet another aspect of the invention, a method is provided for preventing or alleviating a condition or disorder associated with toxic hypervolemia in an individual, comprising administering to said individual a therapeutically effective amount of an exendin or an exendin agonist. By “condition or disorder associated with toxic hypervolemia” is meant any condition or disorder in a subject that is either caused by, complicated by, or aggravated by a relatively high extracellular volume. Such conditions or disorders include, but are not limited to, renal failure, congestive heart failure, nephrotic syndrome, pulmonary edema, cirrhosis, and hypertension. The present invention also provides a method of inducing rapid diuresis in an individual comprising administering to said individual a therapeutically effective amount of an exendin or an exendin agonist. One preferred use of this method is in preparation of a patient for a surgical procedure where a reduction in extracellular volume is desired, such as in some ocular surgical procedures or in some neurosurgical procedures. Thus, the present invention provides a method of preparing an individual for a surgical procedure comprising administering to said individual a therapeutically effective amount of an exendin or an exendin agonist. Preferably, said exendin or exendin agonist is administered to said individual before said surgical procedure. In other preferred aspects, a method is provided for increasing renal plasma flow and glomerular filtration rate in an individual comprising administering to said individual a therapeutically effective amount of an exendin or an exendin agonist. In yet other preferred aspects, a method is provided for treating pre-eclampsia or eclampsia of pregnancy in an individual comprising administering to said individual a therapeutically effective amount of an exendin or an exendin agonist. The preferred mode of administration of said exendin or exendin agonist is by peripheral (subcutaneous or intravenous) administration. Preferably, said exendin or exendin agonist is administered subcutaneously. Preferably, about 1 μg-30 μg to about 10-20 mg of the exendin or exendin agonist is administered per dose. More preferably, about 30 μg to about 10 mg, or about 300 μg to about 5 mg of the exendin or exendin agonist is administered per dose. Most preferably, about 30 μg to about 1 mg of the exendin or exendin agonist is administered per dose. In other preferred aspects, said peripheral administration is selected from the group consisting of buccal, nasal, pulmonary, oral, intraocular, rectal, and transdermal administration. The present invention also provides pharmaceutical compositions for use in the treatment of conditions or disorders associated with hypervolemia comprising a therapeutically effective amount of an exendin or exendin agonist in association with a pharmaceutically acceptable carrier. In yet other aspects, the invention provides pharmaceutical compositions for use in increasing urine flow in an individual comprising a therapeutically effective amount of an exendin or exendin agonist in association with a pharmaceutically acceptable carrier. In further aspects, the invention provides pharmaceutical compositions for use in treating pre-eclampsia or eclampsia of pregnancy in an individual comprising a therapeutically effective amount of an exendin or exendin agonist in association with a pharmaceutically acceptable carrier. Preferably, these pharmaceutical compositions comprise exendin-3. More preferably, these pharmaceutical compositions comprise exendin-4. Preferably, these pharmaceutical compositions comprise an exendin agonist of formula I [SEQ ID NO. 4]. The present invention is also directed to novel methods for increasing urine flow comprising the administration of GLP-1. In one embodiment the invention features a method of increasing urine flow in an individual comprising administering to the individual a therapeutically effective amount of GLP-1 or GLP-1 agonist. By “GLP-1 agonist” is meant a compound that mimics the effects of GLP-1 on increasing urine flow, increasing sodium excretion, and/or decreasing urinary potassium concentration, by binding to the receptor or receptors where GLP-1 causes this effect. Certain GLP-1 agonists are described in Chen et al., U.S. Pat. No. 5,512,549, issued Apr. 30, 1996, entitled “Glucagon-Like Insulinotropic Peptide Analogs, Compositions and Methods of Use.” Other GLP-1 agonists are described in Johnson et al., U.S. Pat. No. 5,574,008, issued Nov. 12, 1996, entitled, “Biologically Active Fragments of Glucagon-Like Insulinotropic Peptide.” Still other GLP-1 agonists are described in Buckley et al., U.S. Pat. No. 5,545,618, issued Aug. 13, 1996, entitled “GLP-1 Analogs Useful for Diabetes Treatment.” All three referenced U.S. patents are incorporated herein by this reference. In certain aspects, the GLP-1 or GLP-1 agonist used in the methods of the present invention can be GLP-1(7-34) and GLP-1(7-35), as disclosed in U.S. Pat. No. 5,118,666, herein incorporated by reference, GLP-1(7-37) as disclosed in U.S. Pat. No. 5,120,712, herein incorporated by reference. In other aspects, the GLP-1 agonists are variants or analogs of GLP-1 known in the art, such as, for example, GLP-1(7-36), Gln9-GLP-1(7-37), D-Gln9-GLP-1(7-37), acetyl-Lys9-GLP-1(7-37), Thr16-Lys18-GLP-1(7-37), and Lys18-GLP-1 (7-37). Derivatives of GLP-1 are also contemplated in the present invention and include, for example, acid addition salts, carboxylate salts, lower alkyl esters, and amides (see, e.g., WO91/11457). Generally, the various forms of GLP-1 are known to stimulate insulin secretion (insulinotropic action) and cAMP formation (see, e.g., Mojsov, S., Int. J. Peptide Protein Research, 40:333-343 (1992)). In still other aspects, the present invention contemplates GLP-1 agonists of the general formula: wherein R1 is selected from the group consisting of 4-imidazopropionyl (des-amino-histidyl), 4-imidazoacetyl, or 4-imidazo-α, αdimethyl-acetyl; R2 is selected from the group consisting of C6-C10 unbranched acyl, or is absent; R3 is selected from the group consisting of Gly-OH or NH2; and Xaa40 is Lys or Arg. In one embodiment, the GLP-1 agonists are naturally-occurring GLP-1(7-37) that arise from adding various R groups via a peptide bond to the amino terminus of the peptide portion of Formula II (SEQ ID NO:66). Optionally, further compounds of the invention are made by acylating the epsilon amino group of the Lys34 residue and by making limited amino acid substitutions at position 26 or by altering the carboxy terminus. It should be noted that for the above formula, the nomenclature scheme used is that which has been developed around processed forms of GLP-1. In this scheme, the amino terminus of the known GLP-1(7-37) OH has been assigned number 7 and the carboxy terminus number 37. Therefore, the first Ala residue of Formula II corresponds to residue 8 of GLP-1(7-37)OH. Likewise Xaa40 in Formula II corresponds to residue 26 of GLP-1(7-37)OH and so forth. In still other aspects, the present invention provides biologically-active GLP-1 fragments of formula III: (SEQ ID NO: 67) R4-Ser-Tyr-Leu-Glu-Gly-Gln-Ala-Ala-Lys-Glu-Phe- Ile-Ala-Trp-Leu-Val-Xaa41-Gly-Arg-R5 wherein R4 is selected from the group consisting of: a) H2 N; b) H2 N-Ser; c) H2 N-Val-Ser; d) H2 N-Asp-Val-Ser; e) H2 N-Ser-Asp-Val-Ser; (SEQ ID NO: 68) f) H2 N-Thr-Ser-Asp-Val-Ser; (SEQ ID NO: 69) g) H2 N-Phe-Thr-Ser-Asp-Val-Ser; (SEQ ID NO: 70) h) H2 N-Thr-Phe-Thr-Ser-Asp-Val-Ser; (SEQ ID NO: 71) i) H2 N-Gly-Thr-Phe-Thr-Ser-Asp-Val-Ser; (SEQ ID NO: 72) j) H2 N-Glu-Gly-Thr-Phe-Thr-Ser-Asp-Val-Ser; (SEQ ID NO: 73) or k) H2 N-Ala-Glu-Gly-Thr-Phe-Thr-Ser-Asp-Val-Ser; (SEQ ID NO: 74) Xaa41 is selected from the group consisting of Lys or Arg; and wherein R5 is selected from the group consisting of NH2, OH, Gly-NH2, or Gly-OH. In still other aspects, the invention provides modified forms of the GLP-1(7-34); (7-35); (7-36) or (7-37) human peptide or the C-terminal amidated forms thereof. The native peptides have the amino acid sequence (SEQ ID NO:75): 7 10 15 20 25 H-A-E-G-T-F-T-S-D-V-S-S-Y-L-E-G-Q-A-A-K-E-F- 30 37 I-A-W-L-V-K-(G)-(R)-(G) wherein (G), (R), and (G) are present or absent depending on the indicated chain length. The modified forms contain one or more alterations of the native structure and are of improved ability for therapeutic use. Either the modified forms have greater potency than glucagon to potentiate insulin secretion or enhanced stability in plasma or both. This potency and enhanced stability can be assessed as described below. The standard one letter abbreviation code for amino acids is used. The analogs of the invention which show enhanced insulin stimulating properties have the foregoing sequence, or the C-terminal amide thereof, with at least one modification of SEQ ID NO:75, selected from the group consisting of: (a) substitution of a neutral amino acid, arginine, or a D form of lysine for lysine at position 26 and/or 34 and/or a neutral amino acid, lysine, or a D form of arginine for arginine at position 36; (b) substitution of an oxidation-resistant amino acid for tryptophan at position 31; (c) substitution according to at least one of: Y for V at position 16; K for S at position 18; D for E at position 21; S for G at position 22; R for Q at position 23; R for A at position 24; and Q for K at position 26; (d) a substitution comprising at least one of: an alternative small neutral amino acid for A at position 8; an alternative acidic amino acid or neutral amino acid for E at position 9; an alternative neutral amino acid for G at position 10; and an alternative acidic amino acid for D at position 15; and (e) substitution of an alternative neutral amino acid or the D or N-acylated or alkylated form of histidine for histidine at position 7. With respect to modifications (a), (b), (d) and (e), the substituted amino acids may be in the D form, as indicated by a superscript †, e.g., C†. The amino acids substituted at position 7 can also be in the N-acylated or N-alkylated forms. In another aspect, the invention is directed to peptides which show enhanced degradation resistance in plasma as compared to GLP-1(7-37) wherein this enhanced resistance to degradation is defined as set forth below. In these analogs, any of the above-mentioned truncated forms of GLP-1(7-34) to GLP-1(7-37) or their C-terminal amidated forms is modified by (a) substitution of a D-neutral or D-acidic amino acid for H at position 7, or (b) substitution of a D-amino acid for A at position 8, or (c) both, or (d) substitution of an N-acylated or N-alkylated form of any naturally occurring amino acid for H at position 7. Thus, analogs of the invention which are resistant to degradation include (N-acyl (1-6C) AA)7 GLP-1(7-37) and (N-alkyl (1-6C) AA)7 GLP-1(7-37) wherein when AA is a lysyl residue, one or both nitrogens may be alkylated or acylated. AA symbolizes any amino acid consistent with retention of insulin stimulating activity. For substitutions of D-amino acids in the 7 and 8 positions of SEQ ID NO:75, the D residue of any acidic or neutral amino acid can be used at position 7 and of any amino acid at position 8, again consistent with insulin stimulating activity. Either or both of position 7 and 8 can be substituted by a D-amino acid; the D-amino acid at position 7 can also be acylated or alkylated as set forth above. These modified forms are applicable not only to GLP-1(7-37) but also the shorter truncated analogs as set forth above. In other aspects of the invention, the increase in urine flow is accompanied by an increase in sodium excretion in said individual. In most preferred aspects, the increase in urine flow does not increase urinary potassium concentration in said individual. In other embodiments of the invention, a method is provided for decreasing the concentration of potassium in the urine of an individual comprising administering to said individual a therapeutically effective amount of GLP-1 or a GLP-1 agonist. In yet another aspect of the invention, a method is provided for preventing or alleviating a condition or disorder associated with toxic hypervolemia in an individual, comprising administering to said individual a therapeutically effective amount of GLP-1 or a GLP-1 agonist. The present invention also provides a method of inducing rapid diuresis in an individual comprising administering to said individual a therapeutically effective amount of GLP-1 or a GLP-1 agonist. One preferred use of this method is in preparation of a patient for surgical procedures where a reduction in extracellular volume is desired, such as in some ocular surgical procedures and some neurosurgical procedures. Thus, the present invention provides a method of preparing an individual for a surgical procedure comprising administering to said individual a therapeutically effective amount of GLP-1 or a GLP-1 agonist. Preferably, said GLP-1 or GLP-1 agonist is administered to said individual before said surgical procedure. In other preferred aspects, a method is provided for increasing renal plasma flow and glomerular filtration rate in an individual comprising administering to said individual a therapeutically effective amount of GLP-1 or GLP-1 agonist. In yet other preferred aspects, a method is provided for treating pre-eclampsia or eclampsia of pregnancy in an individual comprising administering to said individual a therapeutically effective amount of GLP-1 or GLP-1 agonist. The preferred mode of administration of said GLP-1 or GLP-1 agonist is by peripheral administration. Preferably, said GLP-1 or GLP-1 agonist is administered subcutaneously or intravenously. Preferably, about 1 μg-30 μg to about 10-20 mg of GLP-1 or GLP-1 agonist is administered per dose. More preferably, about 30 μg to about 10 mg, or about 300 μg to about 5 mg of GLP-1 or GLP-1 agonist is administered per dose. Most preferably, about 30 μg to about 1 mg of GLP-1 or GLP-1 agonist is administered per dose. In other preferred aspects, said peripheral administration is selected from the group consisting of buccal, nasal, pulmonary, oral, intraocular, rectal, and transdermal administration. The present invention also provides pharmaceutical compositions for use in the treatment of conditions or disorders associated with hypervolemia comprising a therapeutically effective amount of GLP-1 or a GLP-1 agonist in association with a pharmaceutically acceptable carrier. In yet other aspects, the invention provides pharmaceutical compositions for use in increasing urine flow in an individual comprising a therapeutically effective amount of GLP-1 or a GLP-1 agonist in association with a pharmaceutically acceptable carrier. In further aspects, the invention provides pharmaceutical compositions for use in treating pre-eclampsia or eclampsia of pregnancy in an individual comprising a therapeutically effective amount of GLP-1 or a GLP-1 agonist in association with a pharmaceutically acceptable carrier. The present invention also features methods for inducing an inotropic effect in an individual comprising administering a therapeutically effective amount of an exendin or an exendin agonist, or GLP 1 or a GLP 1 agonist. Thus, in one aspect, is provided a method for increasing cardiac contractility in an individual comprising administering a therapeutically effective amount of an exendin, an exendin agonist, GLP-1 or a GLP-1 agonist. In a related aspect, a method is provided for treating a condition or disorder that can be alleviated by increasing cardiac contractility in an individual comprising administering a therapeutically effective amount of an exendin, an exendin agonist, GLP-1 or a GLP-1 agonist. Such conditions or disorders include congestive heart failure, pulmonary and systemic edema, and renal failure. Preferably, said condition or disorder is congestive heart failure. Preferably, said exendin is to be used in those methods exendin-3. More preferably, said exendin is exendin-4. Preferably, the exendin agonist to be used in those methods is an exendin agonist of formula (I) [SEQ ID NO. 4]. In preferred aspects, said exendin, exendin agonist, GLP-1, or a GLP-1 agonist to be used in these methods is administered peripherally using the doses described herein. Preferably, said peripheral administration is selected from the group consisting of buccal, nasal, pulmonary, oral, intraocular, rectal, and transdermal administration. In another preferred aspect, said exendin, exendin agonist, GLP-1, or a GLP-1 agonist is administered subcutaneously or intravenously. Also provided in the present invention are pharmaceutical compositions for use in the treatment of a condition or disorder that can be alleviated by increasing cardial contractility comprising a therapeutically effective amount of an exendin, an exendin agonist, GLP-1 or a GLP-1 agonist in association with a pharmaceutically acceptable carrier. Preferably, said exendin is exendin-3. More preferably, said exendin is exendin-4. Preferably, these pharmaceutical compositions comprise an exendin agonist of formula I [SEQ ID NO. 4]. Part DETAILED DESCRIPTION OF THE INVENTION: The exendins, GLP-1, and analogs and agonists thereof of this invention are useful in view of their pharmacological properties. Activity as exendin or GLP-1 analogs or agonists can be indicated by activity in the assays described below. Effects of exendins or GLP-1 agonists thereof on reducing food intake can be identified, evaluated, or screened for, using the methods described in the Examples below, or other methods known in the art for determining effects on urine flow, or sodium or potassium excretion. Although exendin-4 was found to have a hypertensive effect, when administered in conjunction with an agent that regulated blood pressure, the diuretic effect was still evident, indicating a diuretic effect of exendin-4 that was not entirely attributable to its hypertensive effect. Exendin agonist compounds include those described in U.S. Provisional Patent Application Nos. 60/055,404; 60/066,029; and 60/065,442. Preferred exendin agonist compounds include peptide compounds of the formula (I) [SEQ ID NO. 4]: Xaa1 Xaa2 Xaa3 Gly Xaa5 Xaa6 Xaa7 Xaa8 Xaa9 Xaa10 Xaa11 Xaa12 Xaa13 Xaa14 Xaa15 Xaa16 Xaa17 Ala Xaa19 Xaa20 Xaa21 Xaa22 Xaa23 Xaa24 Xaa25 Xaa26 Xaa27 Xaa28-Z1; wherein Xaa1 is His, Arg or Tyr; Xaa2 is Ser, Gly, Ala or Thr; Xaa3 is Asp or Glu; Xaa5 is Ala or Thr; Xaa6 is Ala, Phe, Tyr or naphthylalanine; Xaa7 is Thr or Ser; Xaa8 is Ala, Ser or Thr; Xaa9 is Asp or Glu; Xaa10 is Ala, Leu, Ile, Val, pentylglycine or Met; Xaa11 is Ala or Ser; Xaa12 is Ala or Lys; Xaa13 is Ala or Gln; Xaa14 is Ala, Leu, Ile, pentylglycine, Val or Met; Xaa15 is Ala or Glu; Xaa16 is Ala or Glu; Xaa17 is Ala or Glu; Xaa19 is Ala or Val; Xaa20 is Ala or Arg; Xaa21 is Ala or Leu; Xaa22 is Phe, Tyr or naphthylalanine; Xaa23 is Ile, Val, Leu, pentylglycine, tert-butylglycine or Met; Xaa24 is Ala, Glu or Asp; Xaa25 is Ala, Trp, Phe, Tyr or naphthylalanine; Xaa26 is Ala or Leu; Xaa27 is Ala or Lys; Xaa28 is Ala or Asn; Z1 is —OH, —NH2, Gly-Z2, Gly Gly-Z2, Gly Gly Xaa31-Z2, Gly Gly Xaa31 Ser-Z2, Gly Gly Xaa31 Ser Ser-Z2, Gly Gly Xaa31 Ser Ser Gly-Z2, Gly Gly Xaa31 Ser Ser Gly Ala-Z2, Gly Gly Xaa31 Ser Ser Gly Ala Xaa36-Z2, Gly Gly Xaa31 Ser Ser Gly Ala Xaa36 Xaa37-Z2, Gly Gly Xaa31 Ser Ser Gly Ala Xaa36 Xaa37 Xaa38-Z2, or Gly Gly Xaa31 Ser Ser Gly Ala Xaa36 Xaa37 Xaa38 Xaa39-Z2; wherein Xaa31, Xaa36, Xaa37 and Xaa38 are independently selected from the group consisting of Pro, homoproline, 3Hyp, 4Hyp, thioproline, N-alkylglycine, N-alkylpentylglycine and N-alkylalanine; Xaa39 is Ser, Thr or Tyr; and Z2 is —OH or —NH2; and pharmaceutically acceptable salts thereof; provided that no more than three of Xaa3, Xaa5, Xaa6, Xaa8, Xaa10, Xaa11, Xaa12, Xaa13, Xaa14, Xaa15, Xaa16, Xaa17, Xaa19, Xaa20, Xaa21, Xaa24, Xaa25, Xaa26, Xaa27, and Xaa28 are Ala; and provided also that the compound is not exendin-3 or exendin-4. Preferred N-alkyl groups for N-alkylglycine, N-alkylpentylglycine and N-alkylalanine include lower alkyl groups preferably of 1 to about 6 carbon atoms, more preferably of 1 to 4 carbon atoms. Suitable compounds include those identified in Examples 4-64 [SEQ ID NOS. 5 to 65], as well as those compounds identified in Examples 65 and 66. Preferred exendin agonist compounds include those wherein Xaa1 is His or Tyr. More preferably Xaa1 is His. Preferred are those compounds wherein Xaa2 is Gly. Preferred are those compounds wherein Xaa14 is Leu, pentylglycine or Met. Preferred compounds are those wherein Xaa25 is Trp or Phe. Preferred compounds are those where Xaa6 is Phe or naphthylalanine; Xaa22 is Phe of naphthylalanine; and Xaa23 is Ile or Val. Preferred are compounds wherein Xaa31, Xaa36, Xaa37 and Xaa38 are independently selected from Pro, homoproline, thioproline and N-alkylalanine. Preferably Z1 is —NH2. Preferably Z2 is —NH2. According to one aspect, preferred are compounds of formula (I) wherein Xaa1 is His or Tyr, more preferably His; Xaa2 is Gly; Xaa6 is Phe or naphthylalanine; Xaa14 is Leu, pentylglycine or Met; Xaa22 is Phe or naphthylalanine; Xaa23 is Ile or Val; Xaa31, Xaa36, Xaa37 and Xaa38 are independently selected from Pro, homoproline, thioproline or N-alkylalanine. More preferably Z1 is —NH2. According to an especially preferred aspect, especially preferred compounds include those of formula (I) wherein: Xaa1 is His or Arg; Xaa2 is Gly or Ala; Xaa3 is Asp or Glu; Xaa5 is Ala or Thr; Xaa6 is Ala, Phe or nephthylalaine; Xaa7 is Thr or Ser; Xaa8 is Ala, Ser or Thr; Xaa9 is Asp or Glu; Xaa10 is Ala, Leu or pentylglycine; Xaa11 is Ala or Ser; Xaa12 is Ala or Lys; Xaa13 is Ala or Gln; Xaa14 is Ala, Leu or pentylglycine; Xaa15 is Ala or Glu; Xaa16 is Ala or Glu; Xaa17 is Ala or Glu; Xaa19 is Ala or Val; Xaa20 is Ala or Arg; Xaa21 is Ala or Leu; Xaa22 is Phe or naphthylalanine; Xaa23 is Ile, Val or tert-butylglycine; Xaa24 is Ala, Glu or Asp; Xaa25 is Ala, Trp or Phe; Xaa26 is Ala or Leu; Xaa27 is Ala or Lys; Xaa28 is Ala or Asn; Z1 is —OH, —NH2, Gly-Z2, Gly Gly-Z2, Gly Gly Xaa31-Z2, Gly Gly Xaa31 Ser-Z2, Gly Gly Xaa31 Ser Ser-Z2, Gly Gly Xaa31 Ser Ser Gly-Z2, Gly Gly Xaa31 Ser Ser Gly Ala-Z2, Gly Gly Xaa31 Ser Ser Gly Ala Xaa36-Z2, Gly Gly Xaa31 Ser Ser Gly Ala Xaa36 Xaa37-Z2, Gly Gly Xaa31 Ser Ser Gly Ala Xaa36 Xaa37 Xaa38-Z2; Xaa31, Xaa36, Xaa37 and Xaa38 being independently Pro homoproline, thioproline or N-methylalanine; and Z2 being —OH or —NH2; provided that no more than three of Xaa3, Xaa5, Xaa6, Xaa8, Xaa10, Xaa11, Xaa12, Xaa13, Xaa14, Xaa15, Xaa16, Xaa17, Xaa19, Xaa20, Xaa21, Xaa24, Xaa25, Xaa26, Xaa27 and Xaa28 are Ala. Especially preferred compounds include those having the amino acid sequence of SEQ ID NOS. 6-27. According to an especially preferred aspect, provided are compounds where Xaa14 is Leu, Ile, Val or pentylglycine, more preferably Leu or pentylglycine, and Xaa25 is Phe, Tyr or naphthylalanine, more preferably Phe or naphthylalanine. These compounds will be less susceptive to oxidative degradation, both in vitro and in vivo, as well as during synthesis of the compound. GLP-1 agonist compounds include those described in U.S. Pat. No. 5,512,549, issued Apr. 30, 1996, U.S. Pat. No. 5,574,008, issued Nov. 12, 1996, and U.S. Pat. No. 5,545,618, issued Aug. 13, 1996, all of which are incorporated by reference. The GLP-1 agonist used in the methods of the present invention can be GLP-1(7-34) and GLP-1(7-35), as disclosed in U.S. Pat. No. 5,118,666, herein incorporated by reference, GLP-1(7-37) as disclosed in U.S. Pat. No. 5,120,712, herein incorporated by reference. GLP-1 agonists can also be variants or analogs of GLP-1 known in the art, such as, for example, GLP-1(7-36), Gln9-GLP-1(7-37), D-Gln9-GLP-1(7-37), acetyl-Lys9-GLP-1(7-37), Thr16-Lys18-GLP-1(7-37), and Lys18-GLP-1(7-37). Derivatives of GLP-1 are also contemplated in the present invention and include, for example, acid addition salts, carboxylate salts, lower alkyl esters, and amides (see, e.g., WO91/11457). Generally, the various forms of GLP-1 are known to stimulate insulin secretion (insulinotropic action) and cAMP formation (see, e.g., Mojsov, S., Int. J. Peptide Protein Research, 40:333-343 (1992)). GLP-1 agonists can be of the general formula II: wherein R1 is selected from the group consisting of 4-imidazopropionyl (des-amino-histidyl), 4-imidazoacetyl, or 4-imidazo-α, αdimethyl-acetyl; R2 is selected from the group consisting of C6-C10 unbranched acyl, or is absent; R3 is selected from the group consisting of Gly-OH or NH2; and, Xaa40 is Lys or Arg. GLP-1 agonists can be naturally-occurring GLP-1(7-37) that arise from adding various R groups via a peptide bond to the amino terminus of the peptide portion of Formula II (SEQ ID NO:66). Optionally, further compounds of the invention are made by acylating the epsilon amino group of the Lys34 residue and by making limited amino acid substitutions at position 26 or by altering the carboxy terminus. It should be noted that for the above formula II, the nomenclature scheme used is that which has been developed around processed forms of GLP-1. In this scheme, the amino terminus of the known GLP-1(7-37) OH has been assigned number 7 and the carboxy terminus number 37. Therefore, the first Ala residue of Formula II corresponds to residue 8 of GLP-1(7-37)OH. Likewise Xaa40 in Formula II corresponds to residue 26 of GLP-1(7-37)OH and so forth. The present invention further contemplates biologically-active GLP-1 fragments of formula III: (SEQ ID NO: 67) R4-Ser-Tyr-Leu-Glu-Gly-Gln-Ala-Ala-Lys-Glu-Phe- Ile-Ala-Trp-Leu-Val-Xaa41-Gly-Arg-R5 wherein R4 is selected from the group consisting of: a) H2 N; b) H2 N-Ser; c) H2 N-Val-Ser; d) H2 N-Asp-Val-Ser; e) H2 N-Ser-Asp-Val-Ser; (SEQ ID NO: 68) f) H2 N-Thr-Ser-Asp-Val-Ser; (SEQ ID NO: 69) g) H2 N-Phe-Thr-Ser-Asp-Val-Ser; (SEQ ID NO: 70) h) H2 N-Thr-Phe-Thr-Ser-Asp-Val-Ser; (SEQ ID NO: 71) i) H2 N-Gly-Thr-Phe-Thr-Ser-Asp-Val-Ser; (SEQ ID NO: 72) j) H2 N-Glu-Gly-Thr-Phe-Thr-Ser-Asp-Val-Ser; (SEQ ID NO: 73) or k) H2 N-Ala-Glu-Gly-Thr-Phe-Thr-Ser-Asp-Val-Ser; (SEQ ID NO: 74) Xaa41 is selected from the group consisting of Lys or Arg; and wherein R5 is selected from the group consisting of NH2, OH, Gly-NH2, or Gly-OH. The present invention also contemplates modified forms of the GLP-1(7-34); (7-35); (7-36) or (7-37) human peptide or the C-terminal amidated forms thereof. The native peptides have the amino acid sequence (SEQ ID NO:75): 7 10 15 20 25 H-A-E-G-T-F-T-S-D-V-S-S-Y-L-E-G-Q-A-A-K-E-F- 30 37 I-A-W-L-V-K-(G)-(R)-(G) wherein (G), (R), and (G) are present or absent depending on the indicated chain length. The modified forms contain one or more alterations of the native structure and are of improved ability for therapeutic use. Either the modified forms have greater potency than glucagon to potentiate insulin secretion or enhanced stability in plasma or both. This potency and enhanced stability can be assessed as described below. The standard one letter abbreviation code for amino acids is used. The analogs of the invention which show enhanced insulin stimulating properties have the foregoing sequence, or the C-terminal amide thereof, with at least one modification of SEQ ID NO:75, selected from the group consisting of: (a) substitution of a neutral amino acid, arginine, or a D form of lysine for lysine at position 26 and/or 34 and/or a neutral amino acid, lysine, or a D form of arginine for arginine at position 36; (b) substitution of an oxidation-resistant amino acid for tryptophan at position 31; (c) substitution according to at least one of: Y for V at position 16; K for S at position 18; D for E at position 21; S for G at position 22; R for Q at position 23; R for A at position 24; and Q for K at position 26; (d) a substitution comprising at least one of: an alternative small neutral amino acid for A at position 8; an alternative acidic amino acid or neutral amino acid for E at position 9; an alternative neutral amino acid for G at position 10; and an alternative acidic amino acid for D at position 15; and (e) substitution of an alternative neutral amino acid or the D or N-acylated or alkylated form of histidine for histidine at position 7. With respect to modifications (a), (b), (d) and (e), the substituted amino acids may be in the D form, as indicated by a superscript †, e.g., C†. The amino acids substituted at position 7 can also be in the N-acylated or N-alkylated forms. In another aspect, the invention is directed to peptides which show enhanced degradation resistance in plasma as compared to GLP-1(7-37) wherein this enhanced resistance to degradation is defined as set forth below. In these analogs, any of the above-mentioned truncated forms of GLP-1(7-34) to GLP-1(7-37) or their C-terminal amidated forms is modified by (a) substitution of a D-neutral or D-acidic amino acid for H at position 7, or (b) substitution of a D-amino acid for A at position 8, or (c) both, or (d) substitution of an N-acylated or N-alkylated form of any naturally occurring amino acid for H at position 7. Thus, GLP-1 agonists of the invention which are resistant to degradation include (N-acyl (1-6C) AA)7 GLP-1(7-37) and (N-alkyl (1-6C) AA)7 GLP-1(7-37) wherein when AA is a lysyl residue, one or both nitrogens may be alkylated or acylated. AA symbolizes any amino acid consistent with retention of insulin stimulating activity. For substitutions of D-amino acids in the 7 and 8 positions of SEQ ID NO:76, the D residue of any acidic or neutral amino acid can be used at position 7 and of any amino acid at position 8, again consistent with insulin stimulating activity. Either or both of position 7 and 8 can be substituted by a D-amino acid; the D-amino acid at position 7 can also be acylated or alkylated as set forth above. These modified forms are applicable not only to GLP-1(7-37) but also the shorter truncated analogs as set forth above. In accordance with the present invention and as used herein, the following terms are defined to have the following meanings, unless explicitly stated otherwise. The term “amino acid” refers to natural amino acids, unnatural amino acids, and amino acid analogs, all in their D and L stereoisomers if their structure allow such stereoisomeric forms. Natural amino acids include alanine (Ala), arginine (Arg), asparagine (Asn), aspartic acid (Asp), cysteine (Cys), glutamine (Gln), glutamic acid (Glu), glycine (Gly), histidine (His), isoleucine (Ile), leucine (Leu), Lysine (Lys), methionine (Met), phenylalanine (Phe), proline (Pro), serine (Ser), threonine (Thr), tryptophan (Trp), tyrosine (Tyr) and valine (Val). Unnatural amino acids include, but are not limited to azetidinecarboxylic acid, 2-aminoadipic acid, 3-aminoadipic acid, beta-alanine, aminopropionic acid, 2-aminobutyric acid, 4-aminobutyric acid, 6-aminocaproic acid, 2-aminoheptanoic acid, 2-aminoisobutyric acid, 3-aminoisobutyric acid, 2-aminopimelic acid, tertiary-butylglycine, 2,4-diaminoisobutyric acid, desmosine, 2,2′-diaminopimelic acid, 2,3-diaminopropionic acid, N-ethylglycine, N-ethylasparagine, homoproline, hydroxylysine, allo-hydroxylysine, 3-hydroxyproline, 4-hydroxyproline, isodesmosine, allo-isoleucine, N-methylalanine, N-methylglycine, N-methylisoleucine, N-methylpentylglycine, N-methylvaline, naphthalanine, norvaline, norleucine, ornithine, pentylglycine, pipecolic acid and thioproline. Amino acid analogs include the natural and unnatural amino acids which are chemically blocked, reversibly or irreversibly, or modified on their N-terminal amino group or their side-chain groups, as for example, methionine sulfoxide, methionine sulfone, S-(carboxymethyl)-cysteine, S-(carboxymethyl)-cysteine sulfoxide and S-(carboxymethyl)-cysteine sulfone. The term “amino acid analog” refers to an amino acid wherein either the C-terminal carboxy group, the N-terminal amino group or side-chain functional group has been chemically codified to another functional group. For example, aspartic acid-(beta-methyl ester) is an amino acid analog of aspartic acid; N-ethylglycine is an amino acid analog of glycine; or alanine carboxamide is an amino acid analog of alanine. The term “amino acid residue” refers to radicals having the structure: (1) —C(O)—R—NH—, wherein R typically is —CH(R′)—, wherein R′ is an amino acid
{'bibliographic_information': "{'country': 'US', 'doc-number': '12247141', 'kind': 'B2', 'date': '20081007', 'extension': '79', 'disclaimer_text': 'This patent is subject to a terminal disclaimer.', 'invention_title': 'Methods of treatment using exendin peptides or GLP-1 peptides'}", 'source_file': './grant/2011/ipg110419.xml', 'source_data': 'USPTO-Grant'}