TETANUS TOXIN INHIBITS SPONTANEOUS QUANTAL RELEASE AND CLEAVES VAMP SYNAPTOBREVIN

Tetanus toxin decreased the frequency of spontaneous events at the ele ctric organ of Torpedo marmorata. This reduction was up to 70% in pois oned electric organ. According to distribution analysis of miniature e nd plate currents, only a subpopulation of events which have small amp litudes were recorded after poisoning. Furthermore, isolated cholinerg ic nerve terminals showed a decrease in VAMP/synaptobrevin when poison ed with tetanus toxin under similar conditions. The relationship betwe en the two effects of the toxin, i.e. inhibition of vesicle exocytosis and peptidase activity on synaptobrevin, is discussed.