INFLUENCE OF ALPHA-RECEPTOR BLOCKADE ON THE TIME-DEPENDENT CHANGE IN THE EFFECT OF FUROSEMIDE

Influence of alpha-receptor blockade on the time-dependent change in t he effect of furosemide (a loop diuretic agent) was examined. Furosemi de (30 mg/kg) was given orally to the doxazosin (an alpha1-blocker)- o r vehicle-treated rats at 12 AM or 12 PM. Urine volume and urinary exc retions of sodium and furosemide for 8 hr were significantly greater a t 12 AM than at 12 PM in the vehicle-treated animals. However, such ti me-dependent changes in these parameters disappeared in the doxazosin- treated rats. These results suggest that the alpha1-receptor-mediated stimuli are involved in the mechanism of the time-dependent change in the effect of furosemide.