Gap junction channels of insects exhibit a residual conductance.
Formation of gap junction coupled cell pairs was used to assess the basic properties of single gap junction channels. For this purpose, two single cells (clone C6/36, derived from larvae of an insect, Aedes albopictus) were maneuvered against each other to provoke gap junction channel insertion. Intercellular current flow was measured with a dual voltage-clamp method. Utilizing this approach, we were able to demonstrate that gap junction channels, after formation, do not close completely upon application of a transjunctional voltage gradient, Vj. Instead, they exhibit a residual conductance, gamma j(residual). On average, gamma j(residual) was 64 +/- 4 pS (n = 40). This corresponds to about 1/6 of the conductance of a fully open channel. The existence of gamma j(residual) explains the observation that the conductance of the entire gap junction, gj, decreases only partially at large Vj.
Weingart
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R
Department of Physiology, University of Berne, Switzerland.
Bukauskas
F F
FF
D000330:Aedes / Q000502:physiology*; D000818:Animals; D002999:Clone Cells / Q000187:drug effects / Q000378:metabolism; D004594:Electrophysiology; D017629:Gap Junctions / Q000502:physiology*; D007473:Ion Channels / Q000502:physiology*
D007473:Ion Channels