Effects of arachidonic acid on ATP-sensitive K+ current in murine colonic smooth muscle cells.
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.
Jun
Jae Yeoul
JY
Department of Physiology, College of Medicine, Chosun University, Kwangju, Korea.
Yeum
Cheol Ho
CH
Park
Yoo Whan
YW
Jang
In Youb
IY
Kong
In Deok
ID
Sim
Jae Hoon
JH
So
Insuk
I
Kim
Ki Whan
KW
You
Ho Jin
HJ
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*
D015221:Potassium Channels; D016718:Arachidonic Acid; D000255:Adenosine Triphosphate