Abstract
NUSHIRO, N., ABE, K., SEINO, M., OMATA, K. and YOSHINAGA, K. The Effects of Intravenous Injection of α-Human Atrial Natriuretic Polypeptide on Blood Pressure, Renal Hemodynamics and Urinary Kinin Excretion in Anesthetized Rabbits. Tohoku J. exp. Med., 1987, 151(2), 221-231-Studies were performed in anesthetized rabbits to examine the effects of α-human atrial natriuretic polypeptide (α-hANP) on blood pressure, renal hemodynamics and urinary kinin excretion. Intravenous bolus injection of α-hANP at a dose of 5μg resulted in a transient increase in renal blood flow from 26.6±2.2 to 33.7±2.2ml/min (p<0.05) and a decrease in mean arterial pressure from 113±1.8 to 107±2.2mmHg (p< 0.01). The calculated renal vascular resistance decreased from 4.50±0.34 to 3.28±0.20mmHg/ml/min (p<0.05). This vasodilatory effect of α-hANP was immediate and lasted for 30min. These hemodynamic alterations were not associated with the changes in glomerular filtration rate estimated by creatinine clearance. Intravenous injection of α-hANP also produced marked increases in urine volume from 1.99±0.43 to 5.7±1.20ml 10min (p<0.01), urinary sodium from 42.2±7.6 to 243±54μEq/10min (p<0.01), urinary potassium from 37.5± 5.5 to 74.8± 10.3μEq/10min (p<0.01), and urinary kinin excretion from 3.44± 0.49 to 5.26±0.82ng/10min (p<0.05). The observed natriuretic effect of α- hANP lasted only for 30min, whereas diuretic and kaliuretic effects were sustained for 120min. Hematocrit levels did not change significantly throughout the experiment. These results indicate that α-hANP is a potent vasodilator substance and that the natriuretic effect induced by the bolus injection of α-hANP is mediated mainly through its renal vasodilatory action. It is also suggested that the renalkinin, at least in part, contributes to the natriuretic effect of α-hANP.
