title: Acetylcholine- and inositol 1,4,5-trisphosphate-induced calcium mobilization in Xenopus laevis oocytes.
abstract: Acetylcholine induces a complex electrical membrane response in Xenopus laevis oocytes. This response is mimicked, and probably mediated by injected inositol 1,4,5-trisphosphate. Oocytes prelabelled with 45Ca released calcium in two phases, the second, slow phase exhibiting first order kinetics of release. Brief exposure of prelabelled oocytes to acetylcholine resulted in a significant increase in the rate of calcium release that returned to control values 2-3 min following the removal of the neurotransmitter. Intracellular injection of inositol 1,4,5-trisphosphate resulted in increased rate of calcium release similar to, but longer than that caused by acetylcholine. Experiments conducted on single oocytes permitted the investigation of the relationship between acetylcholine-induced and inositol 1,4,5-trisphosphate-induced calcium mobilization and the resulting electrical membrane response. Our data reinforce our previous suggestion that inositol 1,4,5-trisphosphate is the intracellular second messenger of the muscarinic membrane electrical response in Xenopus oocytes.
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002132:Calcium Radioisotopes; D002712:Chlorides / Q000097:blood; D005071:Evoked Potentials / Q000187:drug effects; D005260:Female; D015544:Inositol 1,4,5-Trisphosphate; D007295:Inositol Phosphates / Q000494:pharmacology*; D009865:Oocytes / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D013403:Sugar Phosphates / Q000494:pharmacology*; D014981:Xenopus
chemical_list: D002132:Calcium Radioisotopes; D002712:Chlorides; D007295:Inositol Phosphates; D013403:Sugar Phosphates; D015544:Inositol 1,4,5-Trisphosphate; D000109:Acetylcholine; D002118:Calcium