The mechanism of action of several drugs on neuromuscular transmission will be studied by means of microelectrode and voltage clamp techniques. Emphasis will be placed on the study of pancuronium, ketamine and succinylcholine, in comparison of other depolarizing and non-depolarizing blocking agents which have been examined in this project during the past four years. The effects on both presynaptic and postsynaptic elements will be analyzed, and the ionic conductance changes of end-plate membrans will be measured by voltage clamp. This study is expected to provide the basis of improvements of the existing therapeutic agents acting on synaptic and neuromuscular junctions and of developments of newer agents.