Effect of azosemide on the in vitro perfused thick ascending limb of Henle's loop from the mouse

Direct effect of azosemide on the mouse thick ascending limb of Henle's loop was examined by the isolated tubules perfusion technique, and the effect was compared with that of furosemide. Azosemide added to the tubular lumen reversibly suppressed the lumen positive potential (PDt) and decreased the net chloride reabsorption. Dose-response studies of these two drugs suggested that azosemide was about 5 times as potent as furosemide. The more potent effect of azosemide compared with furosemide was confirmed by a paired study in the same tubules. At a concentration of 10(-5) mol/l azosemide suppressed PDt by 91.4%, furosemide by 65.6%.