Camlarus clarkiiの鋏神経の活動電流に関する研究

抄録

The nerve fibers of Cambarus clarkii are all non medulated.
The nerve in the claws consists of the sensoay, motor and inhibitory fibers. Among them, the motor fibers are the thickest and classified in “giant fiber”.
The action potentials led from the nerve trunk are very complicated, for the trunk contains various kind of nerve fibers. The action potential evoked in the sensory fiber is weak, and that evoked in the motor fiber is strong.
A single nerve fiber can be easily prepared by Tazaki's technique. The spike potential led monophasically from the single motor fiber shows a simple scalene-triangular shape. The ascending time of it is 0.1-0.2 msec. and the descending time is 2.5 msec at 100°C. The spike potential is followed by the negtaive and positive after potentials. The former lasts 8.6 msec. and the later more than 42 msec.
The response of motor fiber complies with the “all or nothing principle ”. If the direct current of long duration is made through the nerve, there occur repetitive responses in it. The frequency of the nerve discharges increases according to the increase of the current strength.
The motor fibers are divided into two sorts, i. e. fast and slow fibers. A single impuls propagated in the fast fiber can evoke the contraction of the muscle which is supplied by that nerve fiber. But a single impulse conveyed by the slow fiber can not evoke the muscle contraction. For to evoke the muscle contraction, it needs two or more impulses in the latter case. Strength-duration time relations are pursued in the fast, slow and inhibitory fibers. Weiss' formula is valid for these results.
The value of chronaxie of the fast fiber is about 0.65 msec., and that of slow and inhibitory fibers are 1.3 msec. and 3.35 msec. respectively.