Autoradiographic localization of [125I]-C-ANP compared to [125I]-ANP in rat tissue.

Whole-body autoradiography demonstrated the different distribution of 125I]-C-ANP and 125I]-ANP to rat tissues. Highest enrichment of radioactivity of both labelled peptides was found in the kidney. In some organs we found remarkable differences between 125I]-ANP and 125I]-C-ANP. In the kidney cortex, especially in the glomeruli, as well as in the endocardium, the zona glomerulosa and the medulla of the adrenal gland, where high levels of radioactivity after 125I]-ANP administration were detected, no or just few radioactivity was found after administration of 125I]-C-ANP. On the other hand in the kidney papilla and the outer subcortical medulla, characteristic blackening was found after 125I]-C-ANP administration. Those differences might be important for the understanding of pharmacological actions of ANP analogues.