Regulation of K+ channels in cardiac myocytes by free fatty acids.
Using rat ventricular cells, we studied the actions of free fatty acids and their ability to modulate the ATP-sensitive K+ channel and to activate a new type of ATP-insensitive K+ channel previously identified in rat atrial cells. Perfusion of the cytoplasmic face of the membrane with unsaturated fatty acids (10-50 microM) such as arachidonic, linoleic, and eicosatrienoic acids inhibited the ATP-sensitive K+ channel almost completely; lysophospholipids also markedly inhibited this channel. Inhibition was due to decreases in the frequency and the burst duration of channel openings. Arachidonic acid activated the ATP-insensitive K+ channel with an outwardly rectifying property. Since the level of free fatty acids rises after longer periods of ischemia, we speculate that the ATP-insensitive K+ channel contributes to the late or secondary phase of extracellular K+ accumulation.
Kim
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Department of Physiology and Biophysics, Chicago Medical School, IL 60064.
Duff
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D015126:8,11,14-Eicosatrienoic Acid / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D016718:Arachidonic Acid; D001095:Arachidonic Acids / Q000494:pharmacology; D002462:Cell Membrane / Q000502:physiology; D004553:Electric Conductivity; D005230:Fatty Acids, Nonesterified / Q000494:pharmacology*; D006321:Heart / Q000502:physiology*; D015640:Ion Channel Gating / Q000187:drug effects; D019787:Linoleic Acid; D008041:Linoleic Acids / Q000494:pharmacology; D008246:Lysophospholipids / Q000494:pharmacology; D015221:Potassium Channels / Q000187:drug effects / Q000502:physiology*; D051381:Rats
D001095:Arachidonic Acids; D005230:Fatty Acids, Nonesterified; D008041:Linoleic Acids; D008246:Lysophospholipids; D015221:Potassium Channels; D016718:Arachidonic Acid; D000255:Adenosine Triphosphate; D019787:Linoleic Acid; D015126:8,11,14-Eicosatrienoic Acid