The effect of alpha-bungarotoxin on spontaneous activity in the ventral nerve cord of Limulus polyphemus.

The physiological action of alpha bungarotoxin in the central nervous system of the horseshoe crab Limulus polyphemus was investigated. Two types of effects were produced by the toxin. The predominant effect was an inhibition of spontaneous activity. However, in some instances alpha bungarotoxin caused a stimulation of activity. In both cases the action of the toxin resembled the effect of d-tubocurarine and opposed the effect of carbamylcholine. Both effects of alpha-bungarotoxin were maximal within 15 min and were sustained for at least 2 h. These results suggest that alpha-bungarotoxin acts as a cholinergic antagonist in the central nervous system of Limulus and are consistent with the specific binding of the toxin to an acetylcholine receptor.