Renal effect of atrial natriuretic polypeptide: comparison with standard saluretics

The effects of synthetic alpha-human atrial natriuretic polypeptide (alpha-hANP) on renal hemodynamics and urine production were examined and compared with those of furosemide and trichlormethiazide (TCM) in anesthetized rats. The diuretic effect of alpha-hANP was brief but more powerful. Also, alpha-hANP produced a rapid and acute decrease in blood pressure (BP) accompanied by an increase in renal blood flow (RBF), while furosemide and TCM had no effect on either BP or RBF. Both the free water reabsorption rate (TCH2O) and free water production (CH2O) increased with administration of alpha-hANP but the linear relationship between CH2O and osmolar clearance (Cosm) and that between TCH2O and Cosm were not affected. Furosemide, on the other hand, affected the relationship between TCH2O and Cosm and between CH2O and Cosm. TCM affected only the relationship between CH2O and Cosm. These results suggest that the renal site of action and the mechanism of action of alpha-hANP differ from those of furosemide and TCM.