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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.

Original publication

DOI

10.1152/ajplung.00010.2003

Type

Journal article

Journal

Am J Physiol Lung Cell Mol Physiol

Publication Date

01/2004

Volume

286

Pages

L221 - L230

Keywords

4-Aminopyridine, Adenosine Triphosphate, Animals, Biophysical Phenomena, Biophysics, Carotid Body, Cations, Divalent, Ion Channel Gating, Kinetics, Magnesium, Membrane Potentials, NAD, Nerve Tissue Proteins, Patch-Clamp Techniques, Potassium Channel Blockers, Potassium Channels, Potassium Channels, Tandem Pore Domain, Rats, Tetraethylammonium