Vol. 137. No. 3, 1986 BIOCHEMICAL AND BlOPHYSlCAL RESEARCH COMMUNICATIONS June 30, 1986 Pages 1079-1085 SPECIFIC BINDING OF ATRIAL NATRIURETIC POLYPEPTIDE TO RENAL BASOLATERAL MEMBRANES IN SPONTANEOUSLY HYPERTENSIVE RATS (SHR) AND STROKE-PRONE SHR Hideyuki Saitol i Ken-ichi Inuil, Yasuhisa Matsukawa', Tomonobu Okano Hitoshi Maegawal, Kazuwa Nakao2r3, Narito Morii2, Hiroo'Imura2, Susumu Makino* and Ryohei Horil si 'Department of Pharmacy, Kyoto University Hospital, 2Second Division If Department of Medicine, Faculty of Medicine, Radioisotope Research Center, Kyoto University, Sakyo-ku, Kyoto, 606, Japan 4Shionogi Research Laboratories, Fukushima-ku, Osaka, 553, Japan Received May 13, 1986 The binding of c-human atria1 natriuretic polypeptide (a- hANP) to basolateral membranes ,isolated from renal cortex of spontaneously hypertensive rats (SHR) and stroke-prone SHR (SHR- SP) was measured at O°C and compared with that of Wistar-Kyoto rats (WKY). The binding of lz51-a-hANP in SHR and SHR-SP at 14- 15 weeks old demonstrated different binding profiles compared with that in WRY, though there were no apparent differences of the profiles among WKY, SHR and SHR-SP at 5 weeks old. For the high affinity binding sites, the apparent dissociation constant and the maximal binding capacity in SHR and SHR-SP were signifi- cantly decreased in comparison with those in WKY. The present data suggest that the altered characteristics of specific recep- tors for atria1 natriuretic polypeptide in SHR and SHR-SP may be involved in the development or maintenance of genetic hyperten- sion. 0 1986 Academic Press, Inc. AS atria1 natriuretic polypeptide (ANP) has natriuretic, diuretic and vasorelaxant effects, it has been speculated to be involved in the regulation of electrolyte balance, extracellular fluid volume and blood pressure (1-4). Recently, several groups examined atria1 contents and plasma concentrations of ANP, and biological responses to ANP in spontaneously hypertensive rats (SHR) and stroke-prone SHR (SHR-SP). Decreased ANP levels in the atrium and the increased plasma ANP concentrations were observed * Address correspondence to: Prof. Ryohei Hori, Ph.D. Abbreviations: a-hANP, a-human atria1 natriuretic polypeptide; ANP, atria1 natriuretic polypeptide; WKY, Wistar-Kyoto rats; SHR, spontaneously hypertensive rats; SHR-SP, stroke-prone spontane- ously hypertensive rats; BSA, bovine serum albumin; Hepes, N-2- hydroxyethylpiperazine-N'-2-ethanesulfonic acid 0006-291X/86 $1.50 Copyrighr 8 19X6 by Academic Press, Inc. 1079 All righrs qf reprodlcc’tron ,n ir+ form revrrved.