Effects of atrial natriuretic peptide on angiotensin II-induced antinatriuresis in anesthetized dogs

Inhibitory effects of atrial natriuretic peptide (ANP) on angiotensin II (ANG II)-induced renal responses were examined in anesthetized dogs. ANG II (5 ng/kg per min) was infused intravenously and changes in renal hemodynamics and urine formation were compared between the ANP (10 ng/kg per min)-infused kidney and the contralateral vehicle-infused (control) kidney. ANG II reduced absolute and fractional urinary sodium excretion in both the ANP-infused kidney and the control kidney. ANG II also reduced glomerular filtration rate in the control kidney but not in the ANP-infused kidney. The ANG II-induced reduction in urinary sodium excretion in the ANP-infused kidney was smaller than the response in the control kidney, whereas ANP did not affect the reduction in fractional sodium excretion. These results suggest that ANP prevents hypofiltration and thereby attenuates the antinatriuresis induced by ANG II.