One widely expressed K+ channel, often called the “BK” channel for its “big” single channel conductance, is regulated by intracellular Ca2+ and voltage: at constant voltage, the open probability (Po) increases with [Ca2+]. At constant [Ca2+], Po increases with depolarization. BK channels participate in many physiological processes, including repolarization of the action potential (Adams et al. 1982), frequency tuning in the inner ear (Hudspeth and Lewis 1988), and regulation of neurotransmitter release (Robitaille et al. 1993).
The mechanism of BK channel gating is addressed by a recent paper in this journal (Rothberg and Magleby 1999) and by two papers in this issue (Horrigan et al. 1999; Horrigan and Aldrich 1999). The Magleby and Aldrich labs took very different...
