Endocrinology, Vol 127, 3029-3037, Copyright © 1990 by Endocrine Society

ARTICLES

Prostaglandin F2 alpha-induced calcium transient in ovine large luteal cells: I. Alterations in cytosolic-free calcium levels and calcium flux

JA Wegner, R Martinez-Zaguilan, ME Wise, RJ Gillies and PB Hoyer
Department of Physiology, University of Arizona, Tucson 85724.

The effect of prostaglandin F2 alpha (PGF2 alpha) on cytosolic calcium homeostasis was studied in suspensions of ovine large or small luteal cells from superovulated ewes. In large cells loaded with fura-2 (AM), resting cytosolic-free calcium ([Ca2+]i) was 62 +/- 5 nM (Hanks' medium, pH 7.15), and PGF2 alpha (0.5 microM) induced a rapid transient increase in [Ca2+]i to 152 +/- 6 nM, which then decreased to 97 +/- 6 nM within 3 min and remained at this level for the remainder of the treatment period (10-20 min). PGF2 alpha did not alter intracellular pH (pHi) in cells loaded with snarf-1 (AM) (pHi indicator). The transient nature of the [Ca2+]i increase was due, at least in part, to the ability of PGF2 alpha to stimulate (P less than 0.05) 45Ca2+ efflux. In small cells, resting [Ca2+]i was 57 +/- 5 nM, and no change in [Ca2+]i levels or pHi occurred with the addition of PGF2 alpha. PGF2 alpha also did not affect 45Ca2+ efflux in small cells. Calcium uptake was not significantly altered by PGF2 alpha in large or small cells. Data from kinetic analysis of the calcium transient was best fit to a two- compartment model consisting of a rapidly effluxing compartment and a slowly effluxing compartment. The size and rate constants were 62 +/- 10 nM and 3.6 +/- 1 min-1, respectively, for the rapidly effluxing compartment and 140 +/- 9 nM and 0.02 +/- 0.002 min-1, respectively, for the slowly effluxing compartment. These results provide evidence for a direct effect of PGF2 alpha specifically on the ovine large luteal cell that involves alterations in [Ca2+]i and calcium flux. This effect is likely to be involved in intracellular mediation of the signal for luteal regression.

This article has been cited by other articles:

				A. Sen, E. Choudhary, E. K. Inskeep, and J. A. Flores Effects of Selective Protein Kinase C Isozymes in Prostaglandin2{alpha}-Induced Ca2+ Signaling and Luteinizing Hormone-Induced Progesterone Accumulation in the Mid-Phase Bovine Corpus Luteum Biol Reprod, April 1, 2005; 72(4): 976 - 984. [Abstract] [Full Text] [PDF]

				E. Choudhary, A. Sen, E. K. Inskeep, and J. A. Flores Developmental Sensitivity of the Bovine Corpus Luteum to Prostaglandin F2{alpha} (PGF2{alpha}) and Endothelin-1 (ET-1): Is ET-1 a Mediator of the Luteolytic Actions of PGF2{alpha} or a Tonic Inhibitor of Progesterone Secretion? Biol Reprod, March 1, 2005; 72(3): 633 - 642. [Abstract] [Full Text] [PDF]

				P. B. Hoyer Regulation of Luteal Regression: The Ewe as a Model Reproductive Sciences, March 1, 1998; 5(2): 49 - 57. [Abstract] [PDF]