[I-125] ATRIAL-NATRIURETIC-PEPTIDE BINDING-SITES IN THE AMPHIBIAN TESTIS

Atrial natriuretic peptide-like immunoreactivity (XNP-like IR) was sho wn in the tests of Bufo marinus, in the head of mature spermatozoa att ached to Sertoli cells, interstitial tissue and seminiferous tubules. After spermiation induced by human chorionic gonadotropin (HCG), testi cular spermatozoa failed to show IR. ANP binding sites were localized and characterized in testis of Bufo murinus by quantitative in vitro a utoradiography using [I-125]-ratANP(99-126). Specific ANP binding demo nstrated positive cooper-activity. The data suggest a new biological f unction of ANP in reproduction of male amphibians.