Autoradiographic localization and quantification of rat heart angiotensin converting enzyme.

Quantitative autoradiography with the angiotensin converting enzyme inhibitor [125I]351A revealed the presence of specific binding for this enzyme in the valve leaflets of the rat heart and in the aortic wall. Branches of the coronary arteries showed binding localized throughout the arterial walls. Binding was also present in the heart atria, where it was four-fold higher than in the heart ventricles. These results support the hypothesis of a physiologic role for angiotensin converting enzyme in peptide metabolism in specific heart structures.