Calcium mobilization by muscarinic receptors in human astrocytoma cells: measurements with quin 2.
Activation of muscarinic cholinergic receptors on 1321N1 human astrocytoma cells leads to Ca2+ mobilization as measured by quin 2 fluorescence. Acetylcholine and methacholine were full and potent agonists, while carbachol and muscarine, were fully efficacious but 6- and 10-fold less potent than acetylcholine. The carbachol-induced Ca2+ response was also observed in absence of extracellular Ca2+ and was blocked by muscarinic receptor antagonists but not by organic Ca2+ channel blockers, tetrodotoxin (TTX), tetraethylammonium (TEA) or metal cations, suggesting that Ca2+ is mobilized from intracellular storage sites rather than through plasma membrane ion channels. Muscarinic receptor-mediated Ca2+ release was also detected in kidney epithelial cells but not in rat fibroblasts, glial cells or differentiated neuroblastoma x glioma hybrid cells.
D000634:Aminoquinolines; D000818:Animals; D001253:Astrocytes / Q000502:physiology; D001254:Astrocytoma; D002118:Calcium / Q000502:physiology*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002451:Cell Compartmentation; D002460:Cell Line; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D006801:Humans; D007473:Ion Channels / Q000502:physiology; D051379:Mice; D010276:Parasympatholytics / Q000494:pharmacology; D010277:Parasympathomimetics / Q000494:pharmacology; D011976:Receptors, Muscarinic / Q000502:physiology*
D000634:Aminoquinolines; D002121:Calcium Channel Blockers; D007473:Ion Channels; D010276:Parasympatholytics; D010277:Parasympathomimetics; D011976:Receptors, Muscarinic; C035738:Quin2-acetoxymethyl ester; D002118:Calcium