Vol. 147, No. 3, 1987 September 30, 1987 BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS Pages 957-963 Bovine adrenal chromaffin granules are a site of synthesis of atrial natriuretic factor 1,2 l l ] H. Ong , C. Lazure , T.l. Nguyen , N. McNicoll , N. Seidah l , M. Chr~tien l, and A. De L6anI 1 Clinical Research Institute of Montreal, II0 Pine Ave W., Montreal, 2 Quebec, Canada H2W 1R7 and Faculty of Pharmacy, University of Montreal. Received August 3, 1987 Abstract: We have previously reported the existence of a peptide factor in the adrenal medulla which inhibits aldosterone secretion in cultured bovine zona glomerulosa cells. The acid extracts of chromaffin granules from bovine adrenal medulla were purified by a four step high performance liquid chromatography procedure. Two active fractions exhibited sequence homology 99 126 with bovine atrial natriuretic factor ANF (Ser - l yr ) and its polypeptide precursor (Asn I - Tyr126). The occurence of both precursor and mature forms of ANF within chromaffin granules indicates the endogenous character of ANF in the adrenal medulla and suggests the potential usefulness of cultured adrenal chromaffin cells for investigating the synthesis, maturation and secretion of atrial peptides. ~ z987 Ao~de~icP~ss, znc. Atrial natriuretic factor is a potent, diuretic, natriuretic and vasorelaxant peptide which was first isolated from mammalian atria (1). Cardiomyocytes appear to constitute the major site of synthesis and secretion of this hormone. Immunohistochemical studies have however permitted the localization of the ANF-like immunoreactivity in central nervous system, kidney, in salivary gland (2) as well as in the anterior pituitary and the adrenal medulla (3,4). lhese extracardiac localizations of ANF-like activity suggest additional local paracrine or autocrine functions of ANF both on peripheral and central activities. We have previously reported the existence in the adrenal medulla of a peptide factor which inhibits aldosterone secretion in the cultured bovine adrenal zona glomerulosa cells (5). These observations indicated the occurrence in the adrenal medulla of an aldosterone secretion Abbreviations used in this paper: ANF, atrial natriuretic factor; RRA, radioreceptor assay; RIA, radioimmunoassay; ~FA, trifluoroacetic acid; HFBA, heptafluorobutyric acid; TEAF, triethylamine formate. Address correspondence to Dr Huy Ong, Molecular Pharmacology Lab., Clinical Research Institute of Montreal, llO Pine Ave W., Montreal, Quebec H2W IRT, CANADA. 957 0006-291X/87 $1.50 Copyright © 1987 by Academic' Press, Inc. All rights of reproduction in any form reserved.