Effects of Australian Eastern brown snake (Pseudonaja textilis) venom on the ultrastructure of nerve terminals on the rat diaphragm.

Isolated rat phrenic nerve diaphragm preparations were exposed to the venom of the Eastern brown snake (Pseudonaja textilis). The venom increased the number of 'coated omega figures' in the axolemma of the nerve terminals. The number of synaptic vesicles appeared to be decreased. The increase in coated omega figures in the axolemma is either caused by neurotoxins in the venom slowing down synaptic vesicle recycling or, after binding to axolemmal receptor, being internalized by receptor-mediated endocytosis. Synaptic vesicle recycling and receptor-mediated endocytosis may be related processes in motor nerve terminals.