Effects of human atrial natriuretic peptide on renal function and vasopressin release

To assess the effects of atrial natriuretic peptide (ANP) on the renal function, cardiovascular system, renin-angiotensin-aldosterone system, and vasopressin release, synthetic human ANP (alpha-hANP) was administered at a dose of 0.08 microgram X kg-1 X min-1 iv for 40 min into anesthetized dogs (n = 6). In the control study (n = 6), saline alone was infused. alpha-hANP brought about a significant increase in renal plasma flow, urinary Na and K output, urine flow, and osmolar clearance and a significant decrease in urinary osmolality, free water clearance, and filtration fraction (FF), with no changes in glomerular filtration rate. Plasma Na concentrations and osmolality did not change significantly, but plasma K concentrations fell progressively. Mean arterial blood pressure decreased without any changes in heart rate. Plasma renin activity (PRA), plasma aldosterone concentrations (PAC), and plasma vasopressin concentrations did not rise, but rather PRA and PAC tended to fall during alpha-hANP infusion. In the control study, there were no changes in these parameters except a progressive fall in FF and plasma K concentrations. These results indicate that the alpha-hANP-induced increase in renal blood flow plays an important role in producing natriuresis, but vasopressin may not be involved in the process of diuresis.