Urinary clearance of atrial natriuretic peptide in Pekin ducks

Abstract

To quantify the renal excretion of atrial natriuretic peptide (ANP) in birds, synthetic ANP was infused intravenously into conscious Pekin ducks at rates of 10, 30 and 90 ng/kg per min for 30 min and the relationships between plasma and urine ANP concentrations were monitored by RIA. The infusions of ANP produced dose-dependent elevations in the plasma concentrations of the hormone; however, urinary concentrations and excretion rates did not change significantly from the basal values of 142.2 +/- 21.5 pg/ml and 26.4 +/- 4.5 pg/min per kg respectively. The metabolic clearance rate of ANP remained constant at each infusion dose (approximately 200 ml/min per kg). The urinary clearance rates (< 0.3 ml/min per kg) indicated that the fraction of ANP cleared from the blood via the urine was less than 0.2%. Clearly, excretion of intact ANP via this route is not a quantitatively important means of elimination for this hormone in birds.