Abstract
Electrical synaptic transmission is an essential form of interneuronal communication which is mediated by gap junctions that permit ion flow. Three gene families (connexins, innexins, and pannexins) have evolved to form gap junctional channels. Each gap junctional channel is formed by the docking of the hemichannel of one cell with the corresponding hemichannel of an adjacent cell. To date, there has been a lack of study models to describe this structure in detail. In this study, we demonstrate that numerical simulations suggest that the passive transmembrane ion transport model, based on the generality of ion channels, also applies to hemichannels in non-junctional plasma membranes. On this basis, we established a gap junctional channel model, which describes hemichannels' docking. We simulated homotypic and heterotypic gap junctions formed by connexins, innexins, and pannexins. Based on the numerical results and our theoretical model, we discussed the physiology of hemichannels and gap junctions, including ion blockage of hemichannels, voltage gating of gap junctions, and asymmetry and delay of electrical synaptic transmission, for which the numerical simulations are first comprehensively realized.
Highlights
Electrical synaptic transmission is an essential form of interneuronal communication mediated by gap junctions
Channel Parameters All the parameters of the passive transmembrane ion transport model are recorded in Tables 1–4, of which the definitions can be found in our previous paper (Wang and Liu, 2019)
By observing the interaction of the paired hemichannels (Px1L, Px1R) which form Pannexin 1 (Px1)/Px1 junctional channels, it can be seen that for any Vj, there is uPx1L = uPx1R = 0.9. The hemichannels on both sides almost completely lose their sensitivity, which is quite different from most hemichannels of connexin and innexin families, and it is the reason why Px1/Px1 pairs appear to be almost insensitive to Vj
Summary
Electrical synaptic transmission is an essential form of interneuronal communication mediated by gap junctions. Do gap junctions underlie the functional processes in the mammalian central nervous system, but they play a crucial role in the physiology of poikilothermic vertebrates
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