Figure 1.

Junctional conductance (Gj) of Novikoff hepatoma cell-pairs expressing Cx43. (A). Cells dialyzed with patch-pipette solutions buffered for pH and Ca²⁺. With [Ca²⁺]_i = 0.12 µM or lower, Gj decreases to 40%–50% with τ’s of 35.2 and 22.3 min, at pH_i = 6.1 and 7.2, respectively—note that this is the normal Gj decay of whole-cell-clamped cells. With [Ca²⁺]_i = 0.5–1.0 µM, Gj decreases to ~25%, with τ’s of 5.9 and 6.2 min, at pH_i = 6.1 and 7.2, respectively. (B). In cell-pairs treated for 20 s with 20 µM arachidonic acid (AA), the rapid and reversible Gj drop is prevented by the buffering of Ca²⁺_i with low concentrations of BAPTA. Note that even a [BAPTA]_i as low as 0.1 mM has some inhibitory effect. (A,B) are adapted from Ref. [31] and [32], respectively.