title: Muscarinic cholinergic enhancement of inositide turnover in cerebral nerve endings is not mediated by calcium uptake.
abstract: Muscarinic cholinergic stimulation of rat cerebral nerve endings incubated with 32Pi causes an enhancement of the labeling of phosphatidic acid (PA) and phosphatidylinositol (PI). The involvement of Ca2+ in the stimulation of PA and PI labeling by carbamylcholine (CCh) was investigated. Enhancement of Ca2+-influx with veratridine and the Ca2+-ionophore A23187 caused a vast decrease of the labeling of the polyphosphoinositides, which was not accompanied by an enhancement of the labeling of PA and PI. The dihydropyridine Ca2+-agonist BAY K8644 did not affect phospholipid labeling. A23187, veratridine and BAY K 8644 did not enhance stimulation of the labeling of PA and PI by CCh. When Ca2+ was omitted from the incubation, A23187 caused an enhancement of basal and CCh-stimulated labeling of PA and PI, possibly indicating a particular feature of A23187 unrelated to its iontophoretic properties. The Ca2+-channel antagonists nimodipine, verapamil and flunarizine were virtually without effect on basal and CCh-stimulated labeling of PI and PA. These data support the notion that the muscarinic cholinergic inositide response is not mediated or controlled by Ca2+-flux.
mesh_terms: D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D000818:Animals; D001921:Brain / Q000378:metabolism*; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002217:Carbachol / Q000494:pharmacology*; D002936:Cinnarizine / Q000031:analogs & derivatives / Q000494:pharmacology; D005444:Flunarizine; D008297:Male; D009411:Nerve Endings / Q000378:metabolism*; D009539:Nicotinic Acids / Q000494:pharmacology; D009543:Nifedipine / Q000031:analogs & derivatives / Q000494:pharmacology; D009553:Nimodipine; D010712:Phosphatidic Acids / Q000378:metabolism*; D010716:Phosphatidylinositols / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D014700:Verapamil / Q000494:pharmacology; D014701:Veratridine / Q000494:pharmacology
chemical_list: D009539:Nicotinic Acids; D010712:Phosphatidic Acids; D010716:Phosphatidylinositols; D000001:Calcimycin; D002936:Cinnarizine; D009553:Nimodipine; D014701:Veratridine; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D002217:Carbachol; D014700:Verapamil; D009543:Nifedipine; D005444:Flunarizine; D002118:Calcium