The effect of papaine on the time course of the end-plate current

Papaine is known to detach cholinesterases from the synaptic cleft. It could be expected that this would result in an increase of the amplitude and half-time of the end-plate current. Thus, the effect of papaine on the end-plate current should be similar to the effect of anticholinesterase methanesulfonyl-fluoride.The end-plate current was recorded in frog skeletal muscle at various levels of membrane potential, before and after papaine was added to the bath.The effect of papaine was an increase of the half-time of the end-plate current, similarly as after treatment of the muscle by methanesulfonylfluoride.It seems that both papaine and methanesulfonyl-fluoride have a similar mechanism of action. In either experimental condition hydrolysis of transmitter is decreased or abolished, which results in an increase of the half-time of the end-plate current.This work was supported by the Research Community of Slovenia