O2 sensing by recombinant TWIK-related halothane-inhibitable K+ channel-1 background K+ channels heterologously expressed in human embryonic kidney cells

• DOI: 10.1016/j.neuroscience.2005.07.009
• Publication Date: 2005-09-09T15:51:59Z
• Authors: V.A. Campanucci; S.T. Brown; K. Hudasek; I.M. O’Kelly; C.A. Nurse; I.M. Fearon
• Keywords: 0303 health sciences; Arecombinant expression; Patch-Clamp Techniques; HEK293; 610; Transfection; Recombinant Proteins; Cell Line; Membrane Potentials; 3. Good health; Oxygen; 03 medical and health sciences; Acute hypoxia; Potassium Channels, Tandem Pore Domain; Hypoxia-Ischemia, Brain; Humans; THIK-1 K+ channels

Hypoxic inhibition of K+ channels provides a link between low O2 and cell function, and in glossopharyngeal neurons hypoxic inhibition of a TWIK-related halothane-inhibitable K+ channel-1 (THIK-1)-like background K+ channel regulates neuronal function. In the present study, we examined directly the O2 sensitivity of recombinant THIK-1 channels, expressed in human embryonic kidney (HE293) cells. THIK-1 expression conferred a moderately outwardly rectifying halothane-inhibited and arachidonic acid-potentiated K+ current and invoked a strongly hyperpolarized resting membrane potential. Endogenous K+ currents in untransfected cells were unaffected by either agent. Hypoxia (P(O2), 20 mmHg) reversibly inhibited THIK-1 currents and caused membrane depolarization, effects that were occluded by halothane. Neither the mitochondrial complex I inhibitors rotenone, myxothiazol and sodium cyanide, nor the NADPH oxidase inhibitors diphenylene iodonium and phenylarsine oxide, were effective in inhibiting the O2-sensitivity of THIK-1. Thus, hypoxic inhibition of THIK-1 occurs by a mechanism dissimilar to that which regulates the activity of other members of the background K+ channel family. Given the O2 sensitivity of THIK-1 channels and their abundant expression in the CNS, we raise for the first time the possibility of a physiological and/or pathological role for these channels during brain ischemia.