title: Studies on the involvement of calcium and calmodulin in the action of growth-hormone-releasing factor.
abstract: A possible role for Ca2+ and calmodulin in the action of growth-hormone-releasing factor (GHRF) was investigated. Low extracellular Ca2+ (less than 100 microM), methoxyverapamil, flunarizine, cinnarizine, and Co2+ decreased both basal and GHRF-stimulated growth-hormone secretion, but did not totally inhibit GHRF-stimulated secretion. A calmodulin antagonist, W7, abolished GHRF-stimulated GH secretion, with no effect on basal secretion. It is suggested that GHRF may act primarily by elevating cellular cyclic AMP, which may then modulate calcium mobilization or flux; the increased intracellular Ca2+ concentrations may then activate calmodulin.
mesh_terms: D000818:Animals; D002118:Calcium / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D002147:Calmodulin / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D013006:Growth Hormone / Q000378:metabolism; D013007:Growth Hormone-Releasing Hormone / Q000494:pharmacology*; D066298:In Vitro Techniques; D008297:Male; D008345:Manganese / Q000494:pharmacology; D010903:Pituitary Gland, Anterior / Q000187:drug effects / Q000378:metabolism; D011388:Prolactin / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D002147:Calmodulin; D008345:Manganese; D011388:Prolactin; D013006:Growth Hormone; D013007:Growth Hormone-Releasing Hormone; D002118:Calcium