Postsynaptic effects of DMSO at the frog neuromuscular junction.

Postsynaptic effects of dimethylsulfoxide (DMSO) were studied at the frog cutaneous pectoris neuromuscular junction using electrophysiological techniques and computer assisted analysis. It was found that the average amplitude of extracellularly recorded miniature end-plate potentials (meppse) as well as the time constant of their monoexponential decay (tau) were both elevated in the presence of DMSO. In spite of increased scatter of individual values, amplitude and tau of meppse highly correlated with each other. These results imply that DMSO partially blocked the activity of acetylcholine esterase in addition to its already known presynaptic action of acetylcholine release enhancement. Inhibitory action of DMSO on activity of isolated acetylcholine esterase was previously demonstrated by biochemical methods.