title: Distinct roles of M1 and M3 muscarinic acetylcholine receptors controlling oscillatory and non-oscillatory [Ca2+]i increase.
abstract: We examined ACh-induced [Ca2+]i dynamics in pancreatic acinar cells prepared from mAChR subtype-specific knockout (KO) mice. ACh did not induce any [Ca2+]i increase in the cells isolated from M1/M3 double KO mice. In the cells from M3KO mice, ACh (0.3-3 μM) caused a monotonic [Ca2+]i increase. However, we found characteristic oscillatory [Ca2+]i increases in cells from M1KO mice in lower concentrations of ACh (0.03-0.3 μM). We investigated the receptor specific pattern of [Ca2+]i increase in COS-7 cells transfected with M1 or M3 receptors. ACh induced the oscillatory [Ca2+]i increase in M3 expressing cells, but not in cells expressing M1, which exhibited monotonic [Ca2+]i increases. IP3 production detected in fluorescent indicator co-transfected cells was higher in M1 than in M3 expressing cells. From the examination of four types of M1/M3 chimera receptors we found that the carboxyl-terminal region of M3 was responsible for the generation of Ca2+ oscillations. The present results suggest that the oscillatory Ca2+ increase in response to M3 stimulation is dependent upon a moderate IP3 increase, which is suitable for causing Ca(2+)-dependent IP3-induced Ca2+ release. The C-terminal domain of M3 may contribute as a regulator of the efficiency of Gq and PLC cooperation.
authors.affiliation: Department of Physiology, Juntendo University Faculty of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan.
authors.forename: Kyoko
authors.initials: K
authors.lastname: Nakamura
authors.forename: Kozo
authors.initials: K
authors.lastname: Hamada
authors.forename: Akiko
authors.initials: A
authors.lastname: Terauchi
authors.forename: Minoru
authors.initials: M
authors.lastname: Matsui
authors.forename: Takeshi
authors.initials: T
authors.lastname: Nakamura
authors.forename: Takao
authors.initials: T
authors.lastname: Okada
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Mikoshiba
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D019556:COS Cells; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D004305:Dose-Response Relationship, Drug; D066298:In Vitro Techniques; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D023421:Models, Animal; D010179:Pancreas / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D043643:Receptor, Muscarinic M1 / Q000172:deficiency / Q000187:drug effects / Q000502:physiology*; D043587:Receptor, Muscarinic M3 / Q000172:deficiency / Q000187:drug effects / Q000502:physiology*
chemical_list: D043643:Receptor, Muscarinic M1; D043587:Receptor, Muscarinic M3; D015544:Inositol 1,4,5-Trisphosphate; D000109:Acetylcholine; D002118:Calcium
keywords: BSS; Ca(2+) oscillation; Ca(2+) signaling; Muscarinic acetylcholine receptor; balanced salt solution; mAChR; muscarinic acetylcholine receptors