Adenosine 3',5'-cyclic monophosphate stimulates secretion of alpha-melanocyte-stimulating hormone from permeabilized cells of the intermediate lobe of the rat pituitary gland.
The effect of Mg-ATP and cyclic AMP on the secretion of alpha-melanocyto-stimulating hormone (alpha-MSH) from electrically permeabilized cells of rat intermediate lobe (IL) were investigated. Addition of exogenous Ca2+ stimulated alpha-MSH secretion in a concentration- (EC50 = 4.8 microM) and temperature-dependent manner. This Ca2+-evoked secretion was further enhanced by Mg-ATP and cyclic AMP. Mg-ATP was required for the fully secretory response in the electrically permeabilized IL cells and the maximal secretion was reached at 1 mM. Cyclic AMP in the presence of GTP gamma S also potentiated Ca2+-evoked alpha-MSH secretion to the same magnitude as Mg-ATP. In the absence of Ca2+ both the cyclic AMP and Mg-ATP did not stimulate alpha-MSH secretion from IL cells. The data suggest that Mg-ATP and cyclic AMP may modulate directly the secretory components rather than change intracellular concentration of free Ca2+.
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism / Q000494:pharmacology; D002463:Cell Membrane Permeability; D000242:Cyclic AMP / Q000494:pharmacology*; D004357:Drug Synergism; D009074:Melanocyte-Stimulating Hormones / Q000378:metabolism*; D010902:Pituitary Gland / Q000187:drug effects* / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains
D000255:Adenosine Triphosphate; D009074:Melanocyte-Stimulating Hormones; D000242:Cyclic AMP; D002118:Calcium