Hemichannel activity of G38D mutant Cx40 channels. A, Single sweep whole cell current recordings from parental N2a, WTCx40, G38D, M163V, and G38D+M163V N2a cells in zero CaCl2 saline during a Vm staircase protocol from −80 to +80 mV. High conductance channel openings and closings were evident only in cells expressing G38D. B, G38D hemichannel activity recorded during a +20 to −40 mV Vm step illustrates the activation and deactivation of this channel by depolarizing and hyperpolarizing Vm steps, respectively. C, Current-voltage relationship of the G38D hemichannel measured from three Vm step protocol experiments. The slope conductance, γhc, was 271±10 pS.