title: Inhibitory effects of arachidonic acid on muscarinic current response in single pancreatic acinar cells of rats.
abstract: 1. In single, enzymatically dissociated rat pancreatic acinar cells both acetylcholine (ACh) stimulation and IP3 (inositol 1,4,5-trisphosphate) injection evoke Ca2(+)-dependent transient responses. Exogenously applied arachidonic acid (AA) inhibits both responses in a dose-dependent manner. 2. Arachidonic acid oxidation inhibitors, indomethacin and nordihydroguaiaretic acid, cause no significant changes in ACh- and IP3-induced responses. The inhibitory effects of AA (50 microM) on IP3-induced responses are not influenced by the presence of these oxidation inhibitors. 3. An inhibitor of phospholipase A2 (PLA2), 4-bromophenacyl bromide (4-BPB; 10 microM), augments the ACh-induced response, and it potentiates the IP3-induced response by a factor of 10 to 20. The IP3-induced response, after its complete decay, is recovered by an administration of 4-BPB. 4. The results suggest that an increase in [Ca2+]i, induced by IP3 injection, activates PLA2, and that this resultant release of AA in turn inhibits IP3-dependent Ca2+ mobilization.
authors.affiliation: Department of Physiology, Jichi Medical School, Tochigi-ken, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Maruyama
mesh_terms: D000098:Acetophenones / Q000494:pharmacology; D000109:Acetylcholine / Q000494:pharmacology; D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D001095:Arachidonic Acids / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D066298:In Vitro Techniques; D007213:Indomethacin / Q000494:pharmacology; D015544:Inositol 1,4,5-Trisphosphate / Q000494:pharmacology; D008297:Male; D009637:Masoprocol / Q000494:pharmacology; D009116:Muscarine / Q000037:antagonists & inhibitors*; D010179:Pancreas / Q000187:drug effects*; D010741:Phospholipases A / Q000037:antagonists & inhibitors; D054467:Phospholipases A2; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D000098:Acetophenones; D001095:Arachidonic Acids; D009637:Masoprocol; D009116:Muscarine; D015544:Inositol 1,4,5-Trisphosphate; D010741:Phospholipases A; D054467:Phospholipases A2; D000109:Acetylcholine; C006821:4-bromophenacyl bromide; D002118:Calcium; D007213:Indomethacin