Interaction of atrial natriuretic peptide and amiloride on renal hemodynamics through renal kallikrein and kinins in anesthetized rabbits.

We investigated the interaction of atrial natriuretic peptide (ANP) and amiloride on renal function and the renal kallikrein-kinin system in anesthetized rabbits. The infusion of ANP alone (50 ng/kg/min) induced a natriuretic action with increments in renal blood flow (RBF) and creatinine clearance (Ccr). The infusion of ANP with amiloride (5 mg/kg + 0.04 mg/kg/min) produced a further increase in natriuresis despite the absence of an increase in RBF and Ccr induced by ANP alone. The urinary excretion of kallikrein and kinins was increased by the administration of ANP. However, the pretreatment with amiloride prevented the increase in the urinary excretion of kallikrein and kinins induced by ANP. These results suggest that the additive effect on sodium excretion might be attributable to changes in the tubular handling of sodium, although ANP did not modify the distal tubular function on sodium reabsorption. It is also suggested that the renal kallikrein-kinin system is not causally involved in the increased sodium excretion by ANP.