Figure 2.
Normalized steady-state junctional current (A) and conductance (B) – transjunctional voltage (Ij – Vj and Gj – Vj) curves for 7 heterotypic Cx43/Cx40 cell pairs. Vj was defined relative to the N2a-Cx40 cell pair. Rectification is produced by the enhanced Vj-dependent gating on the Cx40 negative (Cx43 positive) side of the gap junction and reduced gating when the Vj polarities are reversed. Normalized steady-state Ij – Vj (C) and Gj – Vj (D) curves produced under conditions of unilateral 50% reductions in [KCl] exhibited increased rectification when low [KCl] was present on the Cx40-side and became more symmetrical when [KCl] was lowered on the Cx43-side of the gap junction (N = 6 each). Normalized steady-state Ij – Vj (E) and Gj – Vj (F) curves produced by pairing the mutant Cx40E9,13K double mutant with Cx43 dramatically reduced the rectification by reducing both polarities of Vj-dependent gating.