Endocrinology, Vol 133, 1678-1684, Copyright © 1993 by Endocrine Society

ARTICLES

The type 1 angiotensin-II receptor mediates intracellular calcium mobilization in rat luteal cells

JR Pepperell, G Nemeth, Y Yamada and F Naftolin
Department of Obstetrics and Gynecology, Yale University School of Medicine, New Haven, Connecticut 06510.

The intracellular cytosolic calcium concentration ([Ca]i) was determined in cultured rat luteal cells using the calcium-chelating dye fura-2 and microspectrofluorimetry. Angiotensin-II (Ang-II) induced a dose-dependent transient increase in [Ca]i (ED50, 9.0 +/- 6.5 nM). After the initial peak in [Ca]i, cytosolic calcium returned to a secondary elevated basal level that was dependent upon the presence of extracellular calcium. Pretreatment of rat luteal cells with Ang-II (100 nM) desensitized a subsequent response to a higher concentration (1 microM), but did not desensitize a prostaglandin F2 alpha (PGF2 alpha)-induced calcium flux. Although the peak increases in [Ca]i induced by Ang-II (1 microM) and PGF2 alpha (10 microM) were not significantly different, the plateau phase stimulated by PGF2 alpha was significantly higher (P < 0.05) than that stimulated by Ang-II (1 microM). Pretreatment of luteal cells with the type 2 Ang-II receptor antagonist PD 123319 (10 microM) did not inhibit calcium mobilization; however, Ang-II (1 microM)-induced calcium mobilization was dose dependently blocked by the type 1 Ang-II receptor antagonist Losartan (DuP 753). The ID50 for Losartan was 5.2 +/- 1.8 nM. Pretreatment of the luteal cells with the endoplasmic reticulum calcium ATPase inhibitor thapsigargin (1 microM) also blocked Ang-II-induced calcium mobilization. These data demonstrate the presence of the type 1 Ang-II receptor in rat luteal cells, through which Ang-II dose dependently mobilizes calcium from an intracellular source, probably the endoplasmic reticulum.

This article has been cited by other articles:

				K. Hayashi and A. Miyamoto Angiotensin II Interacts with Prostaglandin F2{alpha} and Endothelin-1 as a Local Luteolytic Factor in the Bovine Corpus Luteum In Vitro Biol Reprod, May 1, 1999; 60(5): 1104 - 1109. [Abstract] [Full Text]

				J.R. Pepperell, K. Kommineni, S. Buradagunta, P.J.S. Smith, and D.L. Keefe Transmembrane Regulation of Intracellular Calcium by a Plasma Membrane Sodium/Calcium Exchanger in Mouse Ova Biol Reprod, May 1, 1999; 60(5): 1137 - 1143. [Abstract] [Full Text]

				W. G. Thomas, T. J. Thekkumkara, T. J. Motel, and K. M. Baker Stable Expression of a Truncated AT[IMAGE] Receptor in CHO-K1 Cells J. Biol. Chem., January 6, 1995; 270(1): 207 - 213. [Abstract] [Full Text] [PDF]

				G. Nemeth, J. R. Pepperell, Y. Yamada, A. Palumbo, and F. Naftolin The Basis and Evidence of a Role for the Ovarian Renin-Angiotensin System in Health and Disease Reproductive Sciences, April 1, 1994; 1(2): 118 - 127. [Abstract] [PDF]