Biophysical properties and metabolic regulation of a TASK-like potassium channel in rat carotid body type 1 cells.
The single channel properties of TASK-like oxygen-sensitive potassium channels were studied in rat carotid body type 1 cells. We observed channels with rapid bursting kinetics, active at resting membrane potentials. These channels were highly potassium selective with a slope conductance of 14-16 pS, values similar to those reported for TASK-1. In the absence of extracellular divalent cations, however, single channel conductance increased to 28 pS in a manner similar to that reported for TASK-3. After patch excision, channel activity ran down rapidly. Channel activity in inside-out patches was markedly increased by 2 and 5 mM ATP and by 2 mM ADP but not by 100 microM ADP or 1 mM AMP. In cell-attached patches, both cyanide and 2,4-dinitrophenol strongly inhibited channel activity. We conclude that 1) whilst the properties of this channel are consistent with it being a TASK-like potassium channel they do not precisely conform to those of either TASK-1 or TASK-3, 2) channel activity is highly dependent on cytosolic factors including ATP, and 3) changes in energy metabolism may play a role in regulating the activity of these background K+ channels.
D015761:4-Aminopyridine / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000378:metabolism / Q000494:pharmacology; D000818:Animals; D055592:Biophysical Phenomena; D001703:Biophysics; D002344:Carotid Body / Q000166:cytology* / Q000378:metabolism*; D002413:Cations, Divalent / Q000378:metabolism; D015640:Ion Channel Gating / Q000187:drug effects / Q000502:physiology; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D009243:NAD / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000502:physiology*; D018408:Patch-Clamp Techniques; D026902:Potassium Channel Blockers / Q000494:pharmacology; D015221:Potassium Channels / Q000502:physiology*; D024683:Potassium Channels, Tandem Pore Domain; D051381:Rats; D019789:Tetraethylammonium / Q000494:pharmacology
D002413:Cations, Divalent; C407082:Kcnk9 protein, rat; D009419:Nerve Tissue Proteins; D026902:Potassium Channel Blockers; D015221:Potassium Channels; D024683:Potassium Channels, Tandem Pore Domain; D009243:NAD; C420132:potassium channel subfamily K member 3; D019789:Tetraethylammonium; D000255:Adenosine Triphosphate; D015761:4-Aminopyridine; D008274:Magnesium