How many channels should there be in a gap junction?

The junctional resistance of the gap junctions between the lateral giant axons of the crayfish has been measured in coupled and uncoupled conditions and the number of gap junction particles has been counted under the same conditions. From these two sets of data it can be concluded that the plaque-forming particles observed in freeze fracture replicas of the synaptic area are all gap junctional particles and that their channels are open. Based on this and published results from other isolated pairs of coupled cells, an inverse relationship has been found between the input resistance of the cells and the calculated number of open gap junctional channels between them. The relationship applies to both excitable and nonexcitable cells.