Pulmonary clearance of atrial natriuretic peptides

Pulmonary clearance and metabolism of atrial natriuretic peptides were studied in isolated perfused rat lungs utilizing high performance liquid chromatography and radioimmunoassay analyses. The disappearance rate of atrial peptides from the perfusion medium followed pseudo-first order kinetics and was associated with formation of lower molecular weight products. Pretreatment of the lungs with MK-521, an angiotensin converting enzyme inhibitor, decreased pulmonary clearance values for both atrial natriuretic peptide and atriopeptin III but did not affect clearance of atriopeptin II. Aminopeptidase inhibition also decreased the rate of atrial natriuretic peptide clearance, however carboxypeptidase inhibition did not affect atrial natriuretic peptide, atriopeptin III or atriopeptin II clearance. The results suggest that the lung through uptake and metabolic processes participates in the clearance and enzymatic metabolism of the atrial natriuretic peptides.