<prompt> PGE2 cause all except -Water retentionUterine contractionFlushingDiuresis  <response>: Ans. is a i.e.. Water retention o Prostaglandins and thromboxanes are synthesised from arachidonic acid cobtained from membrane phospholipids due to action of phospholipase A2, rate limiting enzyme. A summary of the actions of major prostaglandins, prostacyclin and thromboxane Organ Prostaglandin E2 PGE2a Prostaglandin F2a PGF2a Prostacyclin PGI2 Thromboxane A2 TXA2 1. Blood vessels Vasodilatation. X BP Vasodilatation, larger veins constrict, little effect on BP Vasodilatation marked and widespread, BP Vasoconstriction 2. Heart Waek inotropic, reflex cardiac stimulation Weak inotropic -- -- 3. Platelets Variable effect -- Antiaggregatory Aggregation and release reaction 4. Uterus Contraction in vivo, relaxes nongravid human uterus in vitro, so fining of cervix contraction in vivo and in vitro, softening of cervix 5. Bronchi Dilatation. Inhibit histamine release Constriction Dilatation mild, inhibit histamine release Constriction 6. Stomach acid secietion, mucus production -- acid secretion weak, mucosal vasodilatation -- 7. Intestine Contracts longitudinal relaxes circular muscles, peristalsis, Cl water secretion Spasmogenic, fluid . Electrolyte secretion weak Weak spasmogenic, inhibit toxin-induced fluid secretion Weak spasmogenic 8. Kidney Natriuresis, Cl reabsorption, inhibit ADH action, vasodilatation, renin release -- Natriuresis, vasodilatation, renin release Vasoconstrict ion 9. CNS Pyrogenic, variety of effects on i.v. inj. 