Isolated Nerve–Muscle Junction

Abstract

A SINGLE muscle fibre with its nerve supply (Fig. 1) has been dissected from the M. adductor longus of the frog (Hyla aurea). This preparation survives for as long as twenty–four hours at a temperature of 18–20°C., and electric potential changes have been recorded from some twenty of these isolated nerve–muscle junctions during activity. In most experiments the muscle fibre was kept in saline at a paraffin interface while the nerve was lifted into the paraffin and stimulated there. A 50–µ diameter platinum wire served as leading electrode at the junction and was insulated except where it made contact with the muscle fibre. It was moved to different positions along the muscle fibre by means of a micrometer adjustment. The second leading electrode was in the saline below the fibre and acted thus as a diffuse lead.