Site of calcium requirement for stimulation of ACTH release in rat anterior pituitary cells in culture by synthetic ovine corticotropin-releasing factor.
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.
D000042:Absorption; D000324:Adrenocorticotropic Hormone / Q000378:metabolism*; D000818:Animals; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism / Q000494:pharmacology; D002478:Cells, Cultured; D003346:Corticotropin-Releasing Hormone / Q000494:pharmacology*; D000242:Cyclic AMP / Q000378:metabolism*; D005260:Female; D010903:Pituitary Gland, Anterior / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains
D000001:Calcimycin; D000324:Adrenocorticotropic Hormone; D003346:Corticotropin-Releasing Hormone; D000242:Cyclic AMP; D002118:Calcium