The hypoxia-sensitive K+ current is sensitive to α-DTX. A) Current recordings (holding potential -80 mV, ΔV 10 mV) of a neurone showing reversibly decreased K+ currents in hypoxic solution. Application of 50 nM α-DTX in normoxic solution in the same neurone prevented the reduction of K+ currents in subsequently applied hypoxia. B) Current-voltage relation of six neurones with reduced K+ currents. After application of 50 nM α-DTX the amplitude of K+ currents did not further decrease in hypoxia. Bath: choline chloride, pipette: potassium fluoride.