The effects of intravenous injection of .ALPHA.-human atrial natriuretic polypeptide on blood pressure, renal hemodynamics and urinary kinin excretion in anesthetized rabbits.

Abstract

Studies were performed in anesthetized rabbits to examine the effects of a-human atrial natriuretic polypeptide (a-hANP) on blood pressure, renal hemodynamics and urinary kinin excretion. Intravenous bolus injection of a-hANP at a dose of 5pg resulted in a transient increase in renal blood flow from 26.6+2.2 to 33.7+2.2 ml/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+0.20 mmHg/ml/min (p <0.05). This vasodilatory effect of a-hANP was immediate and lasted for 30 min. These hemodynamic alterations were not associated with the changes in glomerular filtration rate estimated by creatinine clearance. Intravenous injection of a-hANP also produced marked increases in urine volume from 1.99+0.43 to 5.7+1.20 ml 10 min (p <0.01), urinary sodium from 42.2± 7.6 to 243±54 ,u Eq/ 10 min (p <0.01), urinary potassium from 37.5± 5.5 to 74.8± 10.3 ,u Eq/ 10 min (p <0.01), and urinary kinin excretion from 3.44± 0.49 to 5.26±0.82 ng/ 10 min (p <0.05). The observed natriuretic effect of ahANP lasted only for 30 min, whereas diuretic and kaliuretic effects were sustained for 120 min. Hematocrit levels did not change significantly throughout the experiment. These results indicate that a-hANP is a potent vasodilator substance and that the natriuretic effect induced by the bolus injection of a-hANP is mediated mainly through its renal vasodilatory action. It is also suggested that the renal kinin, at least in part, contributes to the natriuretic effect of a-hANP. a-human atrial natriuretic polypeptide (a-hANP) ; renal hemodynamics ; fluid and electrolyte excretion ; urinary kinin excretion It is well informed that mammalian atrial extract when administered to rats produces a marked natriuresis and diuresis (de Bold et al. 1981;

The effects of atrial natriuretic peptide on renal function and the renin-aldosterone system in anesthetized rabbits.

“…In our previous study in anesthetized rabbits, intravenous bolus injection of ANP at a dose of 5 jig produced a significant decrease in MAP and an increase in RBF with a marked natriuresis and diuresis, whereas these hemodynamic alterations were not accompanied by the change in GFR as estimated by creatinine clearance at 30 min after the injection of ANP (Nushiro et al 1987). But the intravenous injection of ANP might have resulted in a transient increase in GFR that could not have been detected in a 30 min period.…”