ARGININE VASOPRESSIN INFUSION INCREASES PLASMA-LEVELS OF ATRIAL-NATRIURETIC-FACTOR IN HUMANS

Seven normal subjects underwent sequential 20-min infusion of arginine vasopressin (AVP) at 0.5 and 2 ng/(kg.min) and a complete right-side heart hemodynamic evaluation during the study to analyze the effect of this hormone on atrial natriuretic factor (ANF) secretion in humans and to elucidate whether this effect was primary or secondary to the hemodynamic or hormonal changes induced by AVP. Plasma ANF levels increased at the end of the first (P < 0.05) and second (P < 0.01) infusion periods. No significant changes in mean arterial, pulmonary artery, right and left atrial pressures were recorded during the study. Cardiac output (P < 0.05) and heart rate (P < 0.05) decreased, while total vascular resistances (P < 0.05) increased with respect to basal values in both infusion periods. Plasma renin activity decreased (P < 0.01) at the end of the infusion, while plasma aldosterone, epinephrine and norepinephrine showed no significant changes. We conclude that arginine vasopressin increases plasma ANF levels in humans and that this effect cannot be ascribed to hemodynamic or hormonal changes induced by this hormone, suggesting a direct effect of vasopressin on the atrial myocyte.