Abstract
In the present work, the authors investigated the influence of the extension of muscle on the excitatory curve of the end plate.
Some of the end plates transmitted the nerve impulse to the muscle by single stimulus. However, there were various kinds of end plates which needed 2, 3 or ever 4 stimuli to transmit nerve impulse to the muscle.
Consequently, the method in which both condition shock and test shock are given to the innervating nerve does not serve the purpose in the investigations of the excitatory curve of the end plate.
Thus the authors adopted a method, in which the supermaximal stimulus is given to the aneural portion of the curarued muscle and the test shock is given to the innervating nerve, in order to investigate the excitatory curve of the end plate itself. As it is known that the extension of muscle enhances the potential of the end plate, the authors further investigated the changes induced by the extension of muscle in the excitatory curve of the end plate.
For the experiments, curarized sartorius muscle-nerve preparatinn was employed. Condition shock was given at the aneural portion of the muscle end, and the test shock was given at the proximal end of the innervatning nerve.
When the excitatory curve of the end plate was investigated by extending the tibial end of the muscle by 20%, the absolute refractory period was roughly 3 msec, and the relative refractory period was roughly 7 msec.
When the excitatory curve of the end plate was. investigated in a similar manner but without extension of the muscle, the absolute refractory period was roughly 7 msec, and the relative refractory period was roughly 12 msec.
In other words, it was made clear that the extension of the muscle enhances the potential of the end plate, and that simultaneously it shortens the absolute refractory period and the relative refractory period of the end plate itself.
