{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,11,3]],"date-time":"2025-11-03T09:13:12Z","timestamp":1762161192919},"reference-count":0,"publisher":"Portland Press Ltd.","issue":"3","content-domain":{"domain":["portlandpress.com"],"crossmark-restriction":true},"short-container-title":[],"published-print":{"date-parts":[[1981,6,15]]},"abstract":"<jats:p>We examined the role of Ca2+ in the control of basal and hormone-stimulated ornithine decarboxylase activity in isolated pig granulosa cells maintained under chemically defined conditions in vitro. Omission of Ca2+ from the incubation medium (measured Ca2+ concentration 5\u03bcm) decreased basal enzymic activity, and significantly (P&lt;0.01) impaired the response to maximally stimulating doses of either lutropin or follitropin. No significant alteration occurred in the concentration of either gonadotropin required to elicit half-maximal effects. The addition of EGTA (1.27\u20132.0mm) to chelate residual extracellular Ca2+ further decreased hormone-induced rises in ornithine decarboxylase activity. Despite the presence of 1.27mm concentrations of extracellular Ca2+, the administration of presumptive Ca2+ antagonists, believed to impair trans-membrane Ca2+ influx [verapamil (10\u2013100\u03bcm), nifedipine (1\u2013100\u03bcm) or CoCl2 (1mm)] suppressed hormone-stimulated ornithine decarboxylase activity. The inhibitory effects of verapamil or of Ca2+ omission from the medium were not overcome by the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (0.25mm), or by cholera toxin, or by an exogenously supplied cyclic AMP analogue, 8-bromo cyclic AMP. Conversely, micromolar concentrations of a putative bivalent-cation ionophore, A23187, increased significantly the stimulation of ornithine decarboxylase activity by saturating concentrations of lutropin or 8-bromo cyclic AMP. Thus the present observations implicate Ca2+ ions in the modulation of hormone action and cellular function in normal ovarian cells.<\/jats:p>","DOI":"10.1042\/bj1960795","type":"journal-article","created":{"date-parts":[[2015,8,10]],"date-time":"2015-08-10T20:28:08Z","timestamp":1439238488000},"page":"795-801","update-policy":"http:\/\/dx.doi.org\/10.1042\/crossmark_policy","source":"Crossref","is-referenced-by-count":24,"title":["Role of calcium in the modulation of ornithine decarboxylase activity in isolated pig granulosa cells in vitro"],"prefix":"10.1042","volume":"196","author":[{"given":"Johannes D.","family":"Veldhuis","sequence":"first","affiliation":[{"name":"Division of Endocrinology, Department of Medicine, The Milton S. Hershey Medical Center, The Pennsylvania State University, Hershey, PA 17033, U.S.A."}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"James M.","family":"Hammond","sequence":"additional","affiliation":[{"name":"Division of Endocrinology, Department of Medicine, The Milton S. Hershey Medical Center, The Pennsylvania State University, Hershey, PA 17033, U.S.A."}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"288","container-title":["Biochemical Journal"],"original-title":[],"language":"en","link":[{"URL":"http:\/\/portlandpress.com\/biochemj\/article-pdf\/doi\/10.1042\/bj1960795\/564738\/bj1960795.pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"syndication"},{"URL":"http:\/\/portlandpress.com\/biochemj\/article-pdf\/doi\/10.1042\/bj1960795\/564738\/bj1960795.pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2019,10,26]],"date-time":"2019-10-26T02:51:07Z","timestamp":1572058267000},"score":1,"resource":{"primary":{"URL":"https:\/\/portlandpress.com\/biochemj\/article\/doi\/10.1042\/bj1960795\/20886\/Role-of-calcium-in-the-modulation-of-ornithine"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[1981,6,15]]},"references-count":0,"journal-issue":{"issue":"3","published-print":{"date-parts":[[1981,6,15]]}},"URL":"https:\/\/doi.org\/10.1042\/bj1960795","relation":{},"ISSN":["0264-6021"],"issn-type":[{"value":"0264-6021","type":"print"}],"subject":[],"published":{"date-parts":[[1981,6,15]]}}}