Removal of atrial natriuretic peptide by perfused rabbit lungs in situ

Removal of iodinated 28-amino acid atrial natriuretic peptide (125I]ANP) by rabbit lungs was measured by indicator-dilution methods. After bolus injection of 6.5 pmoles of 125I]ANP, 66.9 +/- 2.9% was removed in a single pass through the lungs. Removal was unaltered by a kininase II inhibitor but was reversibly decreased by unlabelled ANP. Thus the lungs can remove ANP from the pulmonary circulation by a mechanism that does not involve hydrolysis by kininase II. Lungs therefore may be involved in regulating systemic concentrations and hence renal and other actions of ANP.