Autoradiographic localization of [125I]endothelin-1 and [125I]atrial natriuretic peptide in rat tissue: a comparative study.

The autoradiographic localization of [125I]endothelin-1 (ET-1) and [125I]atrial natriuretic peptide (ANP) after i.v. administration has been investigated in rats. Labeled peptides are rapidly distributed to tissues and peripheral organs. After administration of [125I]ET-1 (1-21), the highest enrichment of radioactivity was found in the lung, kidney, liver, adrenal gland, and heart. After administration of [125I]ANP (1-28), the highest levels of radioactivity could be observed in the kidney, adrenal gland, and endocardium. Compared to blood levels in both cases, a relative enrichment of radioactivity is also found in the vascular wall of the aorta. For ANP, no distribution of radioactivity in the lung could be observed. Other organs, especially the kidney and the adrenal gland, showed a similar distribution pattern with respect to substructures.