Cotten JF, Zou HL, Liu C, Au JD, Yost CS. Identification of native rat cerebellar granule cell currents due to background K channel KCNK5 (TASK-2).
ACTA ACUST UNITED AC 2004;
128:112-20. [PMID:
15363886 DOI:
10.1016/j.molbrainres.2004.06.007]
[Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/12/2004] [Indexed: 11/18/2022]
Abstract
The TWIK-related, Acid Sensing K (TASK-2; KCNK5) potassium channel is a member of the tandem pore (2P) family of potassium channels and mediates an alkaline pH-activated, acid pH-inhibited, outward-rectified potassium conductance. In previous work, we demonstrated TASK-2 protein expression in newborn rat cerebellar granule neurons (CGNs). In this study, we demonstrate TASK-2 functional expression in CGNs as a component of the pH-sensitive, volatile anesthetic-potentiated, standing-outward potassium conductance (I(K,SO)). Using excised, inside-out patch-clamp technique, we studied CGNs grown in primary culture. We identified four distinct, noninactivating single channel potassium conductances, Types 1-4. Types 1-3 have previously been attributed to TASK-1 (KCNK3), TASK-3 (KCNK9) and TASK-1/TASK-3 heteromers, and TREK-2 (KCNK10) 2P potassium channel function, respectively; however, the Type 4 conductance is currently unassigned. Previous studies demonstrated that Type 4 single channel activity is potentiated by extracellular, alkaline pH and cytoplasmic arachidonic acid (10-20 microM) and inhibited by cytoplasmic tetraethylammonium (TEA; 1 mM). We determined that heterologously expressed TASK-2 channels have single channel gating, conductance properties and pH sensitivity identical to the Type 4 conductance. Additionally, we found that TASK-2 single channel activity, like the Type 4 conductance is potentiated by cytoplasmic arachidonic acid (20 microM) and inhibited by cytoplasmic TEA (1 mM). We conclude that TASK-2 mediates the Type 4 single channel conductance in CGNs as a component of I(K,SO).
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