Effect of erabutoxin B on acetylcholine release and root potentials of the frog spinal cord

Erabutoxin b (ETX), a sea snake neurotoxin with neuromuscular blocking properties, slightly reduced resting ACh release from the isolated fron spinal cord. ETX did not affect ACh release evoked by antidromic stimulation of ventral roots but reduced the ventral-dorsal root potential and prolonged the dorsal-ventral root potential. The latter effect was associated with a reduction in the orthodromically evoked ACh release. It is suggested that ETX did not affect the presynaptic terminals of the motor axon collaterals and that its effects occurred at postsynaptic sites.