PROPERTIES OF A DELAYED-RECTIFIER K-CELL LINE( CHANNEL IN A MOUSE NONFUSING MUSCLE)

Undifferentiated BC3H1 cells express a potassium-selective channel whi ch was studied using whole-cell patch clamp techniques. The channel ex hibits properties comparable to other delayed-rectifier K+ channels, i ncluding activation threshold, moderately slow rate of activation, and slow inactivation. The BC3H1 cell channel is strongly sensitive to th e resting potential of the cell, with much larger current magnitudes d eveloping from more hyperpolarized holding potentials. Recovery from i nactivation is slow and strongly dependent on membrane potential, beco ming more rapid at hyperpolarized voltages. This channel is somewhat s ensitive to extracellular TEA, 4-aminopyridine, and alpha-dendrotoxin, but insensitive to barium, cesium, and charybdotoxin. Dendrotoxin slo ws deactivation significantly. The voltage dependency and kinetic prop erties of this channel are consistent with a role in recovery of membr ane potential following depolarization or possibly in the process of v olume regulation.