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 probably

The effects described are typical of thiazide diuretics, which inhibit the Na/Cl 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.