An Electrophysiological Study on the Differences of Conduction Velocity between the Red and white Muscle Fibers. Part Ⅲ. Changing of Concuction Velocity, Amplitude of Action-potential and Resting-potential according to the Times from the Insertion of Microelectrode into Muscee Fibers.

Using the intracellular microelectrode, the relationship between the freshness of muscle fibers and their electrophysiological charactor was studied in the surgecally exstirpated human m. rectus abdnminis, namely, the decrease rate of their conduction velocity, amplitude of action-potential and resting-potential was measured according to the times from the insertion of microelectrode into muscle fibers aud the following results were obtained. 1. The decrease of conduction velocity was not so obvious for 15 minutes, namely, its average decrease rate was about 10% for 15 minutes. 2. The decrease of amplitude of action-potential and resting-potential was prominent for 15 minutes, namely their average decrease rates were about 50% for 15 minutes. It was further assumed that the main cause of these decrease might be attribute to the mechanical injuly of muscle fibers by the insertion of microelectrode into them. 3. No marked difference was observed between the decrease rate of conduction velocity, amplitude of action-potential and resting-potential of the red and that of white muscle fibers