Site of calcium requirement for stimulation of ACTH release in rat anterior pituitary cells in culture by synthetic ovine corticotropin-releasing factor

• Published in: Life sciences (1973) Vol. 31; no. 26; p. 3057
• Main Authors: Giguere, V, Lefevre, G, Labrie, F
• Format: Journal Article
• Language: English
• Published: Netherlands 27-12-1982
• Subjects: Absorption; Adrenocorticotropic Hormone - metabolism; Animals; Calcimycin - pharmacology; Calcium - metabolism; Calcium - pharmacology; Cells, Cultured; Corticotropin-Releasing Hormone - pharmacology; Cyclic AMP - metabolism; Female; Pituitary Gland, Anterior - metabolism; Rats; Rats, Inbred Strains
• ISSN: 0024-3205
• DOI: 10.1016/0024-3205(82)90075-3

Synthetic ovine corticotropin-releasing factor (CRF) causes a 6- to 8-fold stimulation of ACTH release and cAMP accumulation in rat anterior pituitary cells in culture at ED50 values of 1 and 4 nM, respectively. Removal of Ca2+ from the incubation medium reduces CRF-induced ACTH release by 70% but have no effect on cyclic AMP accumulation. ACTH release induced by 8-Br-cAMP is inhibited by 65% in the absence of Ca2+. The Ca2+ ionophore A23187 does not alter spontaneous ACTH release. Verapamil, a pharmacological agent that blocks Ca2+ entry into cells, has no influence on spontaneous or CRF-induced ACTH release. The present data clearly demonstrate a role of Ca2+ in CRF action at a step subsequent to cAMP formation and suggest that Ca2+ is mobilized from intracellular stores during CRF stimulation.