title: Calcium ions modulate hormonally stimulated progesterone production in isolated ovarian cells.
abstract: Swine granulosa-luteal cells incubated in Ca2+-deficient medium (5 muM final Ca2+ concentration) for short time periods produced diminished quantities of progesterone in response to lutropin. Maximally stimulating effects of prostaglandin E2 and L-adrenaline were also impaired significantly. Diminished progesterone production could not be attributed to alterations in protein synthesis or cell viability. Under Ca2+-deprived conditions, the stimulatory actions of cholera toxin, 3-isobutyl-1-methylxanthine and 8-bromo cyclic AMP were also significantly impeded. Administration of a presumptive antagonist of transmembrane Ca2+ influx (verapamil) or of EGTA to chelate extracellular Ca2+, significantly decreased the total cellular content of Ca2+, and antagonized the actions of lutropin. Micromolar concentrations of trifluoperazine mimicked the suppressive effects of Ca2+ deprivation. Conversely, the bivalent-cation ionophore, ionophore A23187, significantly augmented the stimulation of progesterone produced by lutropin. Thus the present observations implicate Ca2+ in the modulation of hormonally stimulated progesterone production in isolated ovarian cells, and suggest that Ca2+ may influence one or more processes distal to, or independent of, cyclic AMP generation. In addition, the susceptibility of progesterone biosynthesis to inhibition by trifluoperazine suggests a possible role for calmodulin in the ovary.
mesh_terms: D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D000242:Cyclic AMP / Q000494:pharmacology; D004837:Epinephrine / Q000494:pharmacology; D005260:Female; D066298:In Vitro Techniques; D007986:Luteinizing Hormone / Q000494:pharmacology; D010053:Ovary / Q000187:drug effects / Q000378:metabolism*; D011374:Progesterone / Q000096:biosynthesis*; D011458:Prostaglandins E / Q000494:pharmacology; D013268:Stimulation, Chemical; D013552:Swine; D014268:Trifluoperazine / Q000494:pharmacology
chemical_list: D011458:Prostaglandins E; D014268:Trifluoperazine; D011374:Progesterone; D007986:Luteinizing Hormone; D000242:Cyclic AMP; D002118:Calcium; D004837:Epinephrine