title: Characterization of voltage-sensitive calcium channels in a clonal pituitary cell line.
abstract: We have pharmacologically characterized voltage sensitive calcium channels (VSCCs) in GH3 cells, an anterior pituitary clonal cell line known to secrete prolactin and growth hormone. Raising the medium K+ concentration from 5 to 50 mM caused an immediate increase in net 45Ca2+ uptake which remained apparent over a 15 minute time course. 45Ca2+ uptake was maximally stimulated nearly 10-fold over basal levels. This K+-induced stimulation of Ca2+ uptake was not prevented by 10-5M tetrodotoxin or by replacing sodium with choline in the assay medium. Ca2+ uptake was, however, inhibited by several VSCC antagonists: nitrendipine, D-600, diltiazem and Cd2+. Further, the novel dihydropyridine VSCC agonists, BAY K8644 and CGP 28392, enhanced 50 mM K+-stimulated 45Ca2+ uptake and these effects were blocked by nitrendipine.
authors.forename: G A
authors.initials: GA
authors.lastname: Shangold
authors.forename: S
authors.initials: S
authors.lastname: Kongsamut
authors.forename: R J
authors.initials: RJ
authors.lastname: Miller
mesh_terms: D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002460:Cell Line; D002999:Clone Cells; D004305:Dose-Response Relationship, Drug; D007473:Ion Channels / Q000187:drug effects* / Q000502:physiology; D009543:Nifedipine / Q000031:analogs & derivatives / Q000494:pharmacology; D010903:Pituitary Gland, Anterior / Q000378:metabolism*; D010907:Pituitary Hormones / Q000378:metabolism; D010911:Pituitary Neoplasms / Q000378:metabolism; D051381:Rats; D012964:Sodium / Q000378:metabolism
chemical_list: D002121:Calcium Channel Blockers; D007473:Ion Channels; D010907:Pituitary Hormones; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D012964:Sodium; D009543:Nifedipine; D002118:Calcium