Fig. 3. Macroscopic currents recorded from N2a cell pairs containing different combinations of Cx26 and Cx43 and their dependence on transjunctional voltage (V_j). (A) Gap junction currents (I_j) elicited by bipolar pulse protocol from different N2A cell pairs: co-transfected cell pair, N2aCx26/Cx43-N2aCx26/Cx43 (top left panel); homotypic N2aCx43 cell pair (bottom left panel); co-transfected cell N2aCx26/Cx43 heterotypically paired with N2aCx26 cell (top right panel) and homotypic N2aCx26 cell pair (top right panel). (B) Summary plots of normalized instantaneous (open circles) and steady-state (solid circles) g_j versus V_j from 7 co-transfected N2aCx26/Cx43 cell pairs. The continuous curves represent the best fit of g_j,ss(l) data to the Boltzman equation (V_j,0=–97 mV/90 mV, g_j,min=0.3/0.4, z=1.4/1.1 for negative/positive V_j, respectively) and 2^nd order regression (r²=0.63) fit of g_j,ss (O) data.