Figure 4.

Single Cx50D3E gap junction channel activities. Representative single-channel currents recorded from cell 2 (I₂) in response to V_j pulses of −40, −60, −80, and −100 mV applied to cell 1. The corresponding all-points amplitude histograms are shown to the right of each trace. The current recorded from cell 1 (I₁) at −40 mV is presented to show the symmetrical channel activities of I₁ and I₂. Transitions between open and closed states (dashed line) were detected at all V_j pulses tested; however, the channel spent more time in the closed states with increasing V_j steps. No long-lived substate was detected, although the channel frequently showed flickering transitions to incomplete-opening levels. (Inset) An expanded timescale (filtered at 1 kHz, with sampling intervals of 0.1 ms) shows a typical transition to/from incomplete opening and transitions between the fully open and closed states. The fully open state, γ_j, was 140 pS in this recording.