title: Regulation of protein kinases in steady-state contraction of cat gastric smooth muscle.
abstract: Cat gastric smooth muscle strips were used to investigate the involvement of protein kinases in the steady-state contraction induced by 1 microM acetylcholine or 20 mM KCI. The steady-state contraction induced by acetylcholine or KCl was inhibited by EGTA dose dependently. Voltage-dependent Ca2+ channel antagonists dose dependently inhibited the contractions induced by KCI as well as by acetylcholine. Inhibitory effects of voltage-dependent Ca2+ channel antagonists were significantly more prominent on KCI-induced contractions than on acetylcholine-induced contractions. The acetylcholine-induced contraction was dose dependently inhibited by 8-(N,N-diethylamino)octyl-3,4,5-trimethoxybenzoate (TMB-8, a blocker of intracellular Ca2+ release), but the KCl-induced contraction was not inhibited at all. Therefore both intracellular Ca2+ release and extracellular Ca2+ influx seem to be necessary for the acetylcholine-induced contraction, but intracellular Ca2+ release is not necessary for the KCl-induced contraction. Protein kinase C inhibitors, 10 microM 1-(5-isoquinolinylsulfonyl)-2-methyl-piperazine 2HCl (H-7) and 1 microM staurosporine, significantly inhibited the contraction induced by acetylcholine or KCl. Calmodulin antagonists, 30 microM trifluoperazine and 50 microM N-(6-aminohexyl)-5-chloro-2-naphthalenesulfonamide HCI (W-7), however, significantly inhibited the contraction induced by acetylcholine but not by KCl. A tyrosine kinase inhibitor, 50 microM genistein, did not affect the acetylcholine-induced contraction but significantly inhibited the KCl-induced contraction. These results strongly suggest that the involvement of protein kinases in regulation of the steady-state contraction may be agonist-dependent.
authors.affiliation: Department of Physiology, Catholic University Medical College, Socho-gu, Seoul, South Korea.
authors.forename: S S
authors.initials: SS
authors.lastname: Sim
authors.forename: H J
authors.initials: HJ
authors.lastname: Baek
authors.forename: S H
authors.initials: SH
authors.lastname: Yoon
authors.forename: D J
authors.initials: DJ
authors.lastname: Rhie
authors.forename: S J
authors.initials: SJ
authors.lastname: Hahn
authors.forename: Y H
authors.initials: YH
authors.lastname: Jo
authors.forename: M S
authors.initials: MS
authors.lastname: Kim
mesh_terms: D000109:Acetylcholine / Q000037:antagonists & inhibitors; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D002147:Calmodulin / Q000187:drug effects; D002415:Cats; D005260:Female; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects* / Q000378:metabolism; D011189:Potassium Chloride / Q000037:antagonists & inhibitors; D011493:Protein Kinase C / Q000037:antagonists & inhibitors*; D013270:Stomach
chemical_list: D002121:Calcium Channel Blockers; D002147:Calmodulin; D011189:Potassium Chloride; D011493:Protein Kinase C; D000109:Acetylcholine; D002118:Calcium