<prompt> A new diuretic is being studied in human volunteers. Compared with placebo, the new drug increases urine volume, decreases urinary Ca2, increases body pH, and decreases serum K. If this new drug has a similar mechanism of action to an established diuretic, it probablyblocks the NaCl cotransporter in the DCTblocks aldosterone receptors in the CTinhibits carbonic anhydrase in the PCTinhibits the NaK2Cl cotransporter in the TAL  <response>: The effects described are typical of thiazide diuretics, which inhibit the NaCl cotransporter in the distal convoluted tubule. This action facilitates reabsorption of Ca2, which is the basis for the use of thiazides in nephrolithiasis, and which can result in hypercalcemia. The increased load of Na in the collecting tubules leads to increased excretion of both K and Hi, so hypokalemia and alkalosis may occur. 