GLUTATHIONE SUPPRESSES SPONTANEOUS ACTIVITY IN THE FROG SPINAL-CORD

SPONTANEOUS electrical activity in the isolated hemisected frog spinal cord increased in the presence of the SH reductant dithiothreitol (DT T) was reversibly suppressed by the oxidant 5-5'-dithio-bis-(2-nitrobe nzoic acid) (DTNB) and was irreversibly suppressed by the sulphydryl m odifying agents N-ethyl-maleimide (NEM) and monobromotrimethylammonio bimane. Glutathione (GSH), an important natural low molecular weight t hiol, reversibly suppressed spontaneous activity. Cords pretreated wit h glutathione and successively exposed to NEM or bimane maintained the ir normal electrical activity. This indicates tht GSH had interacted w ith the exposed sulphydryls and prevented their reaction with NEM or b imane. Incubation with bimane resulted in fluorescence-labelled neuron es in the dorsal and ventral horns, whereas samples pretreated with NE M or with GSH were not labelled. Neurones appeared again fluorescent i n cords preincubated with GSH and sequentially exposed to NEM or biman e. Both electrophysiological and histochemical methods indicate that e xposed membrane sulphydryls are involved in the genesis and/or modulat ion of spontaneous electrical potentials.