Properties of single Na(+)-activated K+ channels in cultured central neurons of the chick embryo.

Na(+)-activated K+ channels (IK[Na]) of cultured chick brainstem neurons do not run down following excision of inside-out patches, but this occurs within seconds to minutes in cultured chick olfactory bulb neurons. IK[Na] channels of chick brainstem neurons exhibit a main conductance state of 95-105 pS, and also express multiple sub-conductance states. These channels have complex kinetics, with multiple closed and main conductance states. The average lifetime of the main conductance state is not dependent on the Na+ concentration used to activate the channels.