K+ currents recorded from isolated type I carotid body cells were reversibly suppressed by hypoxia (pO2 25 Torr). Inhibition of Ca2+ influx using high Mg2+, low Ca2+ solutions abolished this effect, indicating hypoxia selectively inhibits the Ca2+-activa ted component of K+ currents. The Ca2+ channel blockers D600 and verapamil reversed the suppressive effects of hypoxia. These drugs also partially inhibited Ca2+-independent K+ currents, but this effect was relieved by hypoxia, causing apparent reversal of hypoxic suppression of the K+ currents seen under control conditions.
