title: Effects of arachidonic acid on ATP-sensitive K+ current in murine colonic smooth muscle cells.
abstract: The effects of arachidonic acid (AA) and the mechanism through which it modulates ATP-sensitive K+ (K(ATP)) currents were examined in single smooth muscle cells of murine proximal colon. In the current-clamping mode, AA and glibenclamide induced depolarization of membrane potential. Using 0.1 mM ATP and 140 mM K+ solution in the pipette and 90 mM K+ in the bath solution at a -80 mV of holding potential, pinacidil activated the glibenclamide-sensitive inward current. The potential of these currents was reversed to near the equilibrium potential of K+ by 60 mM K+ in the bath solution. AA inhibited K(ATP) currents in a dose-dependent manner. This inhibition was not changed when 1 mM GDPbetaS was present in the pipette. Chelerythrine, protein kinase C inhibitor, did not block the AA effects. Superoxide dismutase and metabolic inhibitors (indomethacin and nordihydroguaiacretic acid) of AA did not affect the AA-induced inhibition. Eicosatetraynoic acid, a nonmetabolizable analogue of AA, inhibited the K(ATP) currents. These results suggest that AA-induced inhibition of K(ATP) currents is not mediated by G-protein or protein kinase C activation. The inhibitory action is likely to be a possible mechanism of AA-induced membrane depolarization.
authors.affiliation: Department of Physiology, College of Medicine, Chosun University, Kwangju, Korea.
authors.forename: Jae Yeoul
authors.initials: JY
authors.lastname: Jun
authors.forename: Cheol Ho
authors.initials: CH
authors.lastname: Yeum
authors.forename: Yoo Whan
authors.initials: YW
authors.lastname: Park
authors.forename: In Youb
authors.initials: IY
authors.lastname: Jang
authors.forename: In Deok
authors.initials: ID
authors.lastname: Kong
authors.forename: Jae Hoon
authors.initials: JH
authors.lastname: Sim
authors.forename: Insuk
authors.initials: I
authors.lastname: So
authors.forename: Ki Whan
authors.initials: KW
authors.lastname: Kim
authors.forename: Ho Jin
authors.initials: HJ
authors.lastname: You
mesh_terms: D000255:Adenosine Triphosphate / Q000502:physiology*; D000818:Animals; D016718:Arachidonic Acid / Q000494:pharmacology*; D003106:Colon / Q000187:drug effects* / Q000502:physiology; D005260:Female; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D051379:Mice; D008807:Mice, Inbred BALB C; D032389:Myocytes, Smooth Muscle / Q000187:drug effects* / Q000502:physiology; D015221:Potassium Channels / Q000502:physiology*
chemical_list: D015221:Potassium Channels; D016718:Arachidonic Acid; D000255:Adenosine Triphosphate