[Roles of cyclic AMP and calcium in the mechanism of the release of growth hormone by somatocrinin].

Growth hormone (GH) release from Rat pituitary cell monolayers in response to synthetic somatocrinin (7.8 to 1,000 pmol/l) is paralleled with an increase in cellular cyclic AMP (cAMP) content and efflux of cAMP in the extracellular medium. Somatostatin and blockers of calcium-dependent cellular mechanisms inhibit somatocrinin-induced GH release but only partially decrease (somatostatin, CoCl2) or even increase (trifluoperazine) cAMP levels. Thus, calcium is required for somatocrinin action and GH release is not simply dependent on stimulation of cAMP metabolism.