Pharmacokinetics of atrial natriuretic peptide in Pekin ducks.

To quantify the pharmacokinetics of atrial natriuretic peptide (ANP) in the blood of Pekin ducks, synthetic avian ANP was intravenously infused at various rates and the associated plasma concentrations of immunoreactive ANP (irANP) were measured by radioimmunoassay. At rates of 10, 25, 50, 100, and 200 ng/kg/min, steady-state arterial plasma levels, achieved within 10 min, showed a linear dose-plasma level-response relationship which indicated a mean plasma clearance rate of 174.4 +/- 5.4 ml/kg/min. After stopping the 200 ng/kg/min infusion of ANP, the decay curve of plasma irANP was consistent with first-order kinetics, with the peptide having an elimination half-life time of 1.2 min. It is concluded that ANP is rapidly removed from the circulation of Pekin ducks.