[Molecular pharmacology in diuretics].

Recently, much knowledge of the molecular mechanism of diuretic actions has been accumulated. Molecular cloning of carbonic anhydrase revealed a difference in isozymes and the localization of each isozymes was also identified. Carbonic anhydrase VI, located in brush border of the proximal tubules, is inhibited by acetazolamide. Loop diuretics, furosemide, bumetanide, piretanide and ethacrynic acid, inhibit Na(+)-K(+)-Cl(-)-cotransport system in the thick ascending limb of the Henle's loop. The histochemical localization and biological characterization were investigated by using [3H]-bumetanide. Loop diuretics cotransport protein and inhibit Na+ and Cl- reabsorption. Spironolactone inhibits the binding of aldosterone and cytosol mineralocorticoid receptor in the cortical connecting tubule competitively.