Muscarinic receptor-mediated increase in cytoplasmic free Ca2+ in isolated bovine adrenal medullary cells. Effects of TMB-8 and phorbol ester TPA.
The change in cytoplasmic free calcium, [Ca2+]i in isolated bovine adrenal medullary cells during stimulation by acetylcholine (ACh) in Ca2+-free incubation medium was measured using the fluorescent Ca2+ indicator quin2. ACh (1-100 microM) caused an increase in [Ca2+]i by mobilization of Ca2+ from the intracellular pool. Nicotine (10 microM) did not increase [Ca2+]i in the absence of extracellular Ca2+. Pretreatment of the cells with atropine (10 microM) completely inhibited ACh-induced increase in [Ca2+]i, whereas pretreatment with hexamethonium (100 microM) did not. The intracellular Ca2+ antagonist 8-(N,N-diethylamino)octyl-3,4,5-trimethoxybenzoate (TMB-8), inhibited ACh-induced increase in [Ca2+]i. The activator of protein kinase C 12-O-tetradecanoylphorbol-13-acetate (TPA), but not its 'inactive' analog 4 alpha-phorbol-12,13-didecanoate (PDD), also inhibited ACh-induced increase in [Ca2+]i. These findings suggest that in bovine adrenal medullary cells, stimulation of muscarinic ACh receptor causes an increase in [Ca2+]i by mobilizing Ca2+ from the intracellular pool and that protein kinase C is involved in 'termination' or 'down regulation' of this response.
D000109:Acetylcholine / Q000494:pharmacology; D000313:Adrenal Medulla / Q000378:metabolism*; D000634:Aminoquinolines; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D002417:Cattle; D003600:Cytosol / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D005456:Fluorescent Dyes; D005707:Gallic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology; D066298:In Vitro Techniques; D010704:Phorbols / Q000494:pharmacology*; D011493:Protein Kinase C / Q000378:metabolism; D011976:Receptors, Muscarinic / Q000187:drug effects / Q000502:physiology*; D013050:Spectrometry, Fluorescence; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*
D000634:Aminoquinolines; D002121:Calcium Channel Blockers; D005456:Fluorescent Dyes; D010704:Phorbols; D011976:Receptors, Muscarinic; C006014:8-(N,N-diethylamino)octyl-3,4,5-trimethoxybenzoate; D005707:Gallic Acid; D011493:Protein Kinase C; D000109:Acetylcholine; D013755:Tetradecanoylphorbol Acetate; C035739:Quin2; D002118:Calcium