Gating of Channels in Nerve and Muscie: A Stochastic Approach

Publisher Summary Gating is the process that underlies the opening and closing of channels. This simplistic view suggests that channels are merely rigid pores, which can be opened and closed by a gate. It is becoming apparent, however, that open channels are not necessarily rigid pores, and that gating processes, when fast enough, cannot be distinguished from open channel properties. In spite of this ambiguity, channels often appear to open and close in discrete jumps. This chapter addresses some of the experimental and theoretical details of this process. Several aspects of gating are common to most, if not all, types of ionic channels. The general properties of the gating of single channels are discussed in the chapter. One might imagine that a channel opens slowly as it undergoes a conformational change from a resting to an activated state. For example, a “gate” could open in tiny increments, with the conductance of the single channel increasing in tiny increments. Alternatively, a channel could flip suddenly into and out of a conducting state. Choosing the correct alternative requires single-channel recording; noise measurements alone cannot do it. Stochastic representations of channel gating and experimental findings are discussed in the chapter.