Gap Junction

consist of a pair of cylinders (hemi-channels)
each hemi-channel cylinder를 connexon이라 한다.
각 connexon은 6개의 connexin으로 구성

Gap junction 채널은 항상 열려있지 않다.
heart muscle, smooth muscle 등에 많다.
pH decrease---> close gap junction
elevated cytoplasmic Ca2+---> close

3.5 nm separation between pre- and post-synaptic cell
Ephaptic transmission: by insufficient insulation, by axonal hyperexcitability