Figure 8. A non-inactivating M-like current was strongly blocked by TEA.

A, in voltage clamp, TEA (15 mM) strongly reduced the persistent outward current. Current recordings were obtained using slow voltage ramps (-30 to -100 mV, 10 mV s⁻¹) and the cell was held at -30 mV between ramps. B, an M-like decay was observed when the channels were closed by a negative voltage step; sensitivity to TEA was similar to that obtained from ramps. C, TEA also inhibited a high threshold outward current (left traces); the TEA-sensitive current showed a very slow activation time constant (right trace). D, the non-inactivating current at -30 mV was not affected by 4-AP (2 mM). E, barium (1 mM) also inhibited the persistent M-like current at -30 mV; this can be observed using voltage ramps or negative voltage steps (inset).