Uncoupling of electrotonic synapses by calcium.

Publisher Website
Google Scholar
Abstract
The degree of axo-axonal synaptic coupling between nerve cells in the buccal ganglion of Navanax inermis was investigated in relation to intracellular Ca2+. Increasing intracellular Ca2+ by injection of Ca2+, injection of Na+, or application of ionophore X-537A produced uncoupling after at least 90 min, if metabolic inhibitor was present in the medium. Subsequent removal of the metabolic inhibitor reestablished the coupling in less than 30 min. Injected Sr2+ mimicked the uncoupling action of Ca2+. The presence of a metabolic inhibitor alone had no effect on the coupling. Uncoupling was probably due to an increased free Ca2+ concentration at the junctions. The liberation of endogenous sequestered Ca2+ was not sufficient to produce uncoupling except if an excess Ca2+ had been previously sequestered. The electrical synapses in the buccal ganglion of Navanax appeared to be affected by Ca2+ in a similar way as gap junctions studied in non-neural tissues.