Figure 1.

Cx43 hemichannels in cell-attached patches from Cx43-expressing C6 cells. A, Cell-attached patch recording with the pipette solution containing 130 mm Na₂ATP (top trace) or NaCl (bottom traces) and 20 mm TEA showed the opening (o) and closing (c) states of Cx43 hemichannels. Voltage steps of −160 to 0 mV were applied to the patch pipette. V_m that was the difference between a voltage step and the RMP was presented at the left of each trace. A substate of long openings with slow transitions was also observed (o_sub and arrows). B, The I–V relationship for cell-attached recordings with NaCl (open circle, n = 5 patches) or Na₂ATP (closed circle, n = 6 patches). C, The I–V current of Cx43 hemichannels with MgATP (MgATP) in the patch pipette. D, Open and closed time distributions for a Cx43 hemichannel with a Na₂ATP pipette at holding potential of 70 mV. The decay constant (τ) for open and closed time was calculated by exponential regression with one and two constants, respectively. The numbers indicate the mean decay constants (τ). E, The mean open time constant at different holding potentials. The open time of Cx43 hemichannels is rectified. n = 6 channels. F, Inside-out patch recording from a representative inside-out patch showed fast-gating openings (o_f) and slow-gating openings (o_s). A subconductance of slow-gating openings (o_sub) was also observed. The inside-out patch was excised from the cell-attached patch configuration into the artificial CSF solution. V_m across patches was +80 mV. G, The I–V relationship for inside-out recordings with voltage steps. Error bars indicate SEM.