HUMAN CONNEXIN-43 GAP JUNCTION CHANNEL GATING - EVIDENCE FOR MODE SHIFTS AND OR HETEROGENEITY/

The gating parameters of human connexin 43 (Cx43) gap junction channel s were determined using dual whole cell patch clamp and methods design ed for analysis of multichannel recordings. Under steady-state conditi ons, the mean open time (MOT) of Cx43 gap junction channels was comput ed and it ranged from 0.43 to 5.25 s. The computed mean closed times ( MCT) varied from 0.21 to 1.49 s. Analysis showed that, while the MOT d eclined with increasing transjunctional voltage (V-j), the apparent de cline in the MCT with V-j was not statistically significant. The calcu lated open probabilities ranged from 0.50 to 0.95. Inspection of the d ata showed that there was a prolonged decay in junctional current, whi ch had a time course of 60-150 s. The analysis excluded the possibilit y of a homogeneous voltage inactivated/deactivated population of indep endent and identical Cx43 gap junction channels. The analysis provided evidence for a homogeneous population of Cx43 channels, which can mod e shift under the influence of voltage. The latter case cannot be dist inguished from a heterogeneous population of Cx43 channels in which on e population is voltage inactivated/deactivated and another is unaffec ted or weakly inactivated/deactivated by voltage.