AJP - Endocrinology and Metabolism, Vol 266, Issue 1 E50-E56, Copyright © 1994 by American Physiological Society
Prostaglandin F2 alpha releases calcium from a thapsigargin-sensitive pool in ovine large luteal cells
J. A. Wegner, R. Martinez-Zaguilan, R. J. Gillies and P. B. Hoyer
Department of Physiology, Arizona Health Sciences Center, University of Arizona, Tucson 85724.
Thapsigargin (TG) and A23187 were used to examine the regulation of
cytosolic free calcium (Cai2+) in ovine large and small luteal cells.
Thapsigargin (50 nM) induced a sustained increase of Cai2+ in fura
2-acetoxymethyl ester (AM)-loaded cells (large = 1.32 +/- 0.07-fold, small
= 1.45 +/- 0.07-fold, P < 0.05). A23187 (1 microM) induced a rapid
transient increase of Cai2+ (large = 1.37 +/- 0.07-fold, small = 1.46 +/-
0.10-fold, P < 0.05). In large cells, 0.5 microM prostaglandin F2 alpha
(PGF2 alpha) increased Cai2+ 1.54 +/- 0.11-fold. Pretreatment with 50 nM TG
abolished the PGF2 alpha-induced calcium response. Pretreatment with PGF2
alpha attenuated (P < 0.05) the TG-induced Cai2+ increase. Progesterone
secretion was significantly (P < 0.05) inhibited by incubation with 50
nM TG, 1 microM A23187, and 0.5 microM PGF2 alpha in large but not small
cells. These data suggest that PGF2 alpha releases calcium from a
TG-sensitive intracellular calcium pool in ovine large luteal cells.
