Binding sites for atrial natriuretic peptide in the kidney and aorta of the hagfish (Myxine glutinosa)

1. In the atlantic hagfish (Myxine glutinosa) binding sites for atrial natriuretic peptide (ANP) were visualized by autoradiography in contractile structures of the renal system (glomeruli, neck segment, and archinephric duct) and in the aorta. 2. Since the location of binding sites is comparable to that in higher vertebrates including man, these results suggest that ANP may act as a hormone already in cylcostomata.