Coenzyme Q10 attenuates cyanide-activation of the ATP-sensitive K+ channel current in single cardiac myocytes of the guinea-pig.
The effect of coenzyme Q10 (CoQ10) on the cyanide (CN-)-induced ATP-sensitive K+ channel current (KATP) was examined in single atrial myocytes, using the patch clamp technique. Superfusion of the cells with a CN-/low glucose bathing solution induced an outward current in the whole-cell clamp condition. Glibenclamide (1 microM) abolished this current, indicating that the current was carried through the KATP channel. After steady-state activation by CN-, pinacidil (a KATP channel opener, 300 microM) failed to further increase the current. In cell-attached patches, CN-, when applied to the bath, induced bursting openings of an 80 pS channel (the KATP channel). In cells preincubated for 30 min in a solution containing CoQ10 (100 micrograms/ml), CN(-)-activation of the KATP channel was markedly attenuated both at the whole cell and at the single channel level. At the steady-state effect of CN- in CoQ10-treated cells, pinacidil (300 microM) activated the current to the maximum level achieved by CN- in the control cells. These results suggest that CoQ10 reduces in the CN(-)-induced KATP current not by affecting the channel itself but by preventing depletion of intracellular ATP caused by CN-.
Ito
H
H
2nd Department of Internal Medicine, Faculty of Medicine, University of Tokyo, Japan.
Nakajima
T
T
Takikawa
R
R
Hamada
E
E
Iguchi
M
M
Sugimoto
T
T
Kurachi
Y
Y
D000255:Adenosine Triphosphate / Q000096:biosynthesis / Q000502:physiology*; D000818:Animals; D003067:Coenzymes; D003486:Cyanides / Q000494:pharmacology*; D006168:Guinea Pigs; D006321:Heart / Q000187:drug effects*; D009206:Myocardium / Q000166:cytology / Q000378:metabolism / Q000648:ultrastructure; D015221:Potassium Channels / Q000187:drug effects*; D013997:Time Factors; D014451:Ubiquinone / Q000031:analogs & derivatives* / Q000494:pharmacology
D003067:Coenzymes; D003486:Cyanides; D015221:Potassium Channels; D014451:Ubiquinone; D000255:Adenosine Triphosphate; C024989:coenzyme Q10