The effect of metabolic inhibitors on the cockroach nerve-muscle synapse.

1. The application of metabolic inhibitors to nerve-muscle synapses on 'white' and 'red' fibres in the retractor unguis muscles of P. americana and B. giganteus resulted in a dramatic increase in the spontaneous miniature potential discharge and was accompanied by a summation of the miniature potentials to form 'composite' potentials. 2. Axon terminals associated with 'white' muscle fibres responded faster to metabolic inhibitors than those axon terminals associated with 'red' muscle fibres. 3. Correlated ultrastructural and electrophysiological studies inferred that a tentative relationship existed between the miniature potential activities and synaptic vesicle distributions of the nerve-muscle synapses during the phases of metabolic inhibition.