THE EFFECT OF PROLONGED ACTIVITY ON THE IRRITABILITY OF MEDULLATED NERVE

Abstract

The frog''s sciatic was stimulated at a frequency of 100 per sec. for periods of 4 to 17 min., the attached gastrocnemius being protected during this time by cold or galvanic block. The excitability of the motor fibers was then tested at another point on the nerve by the chronaximetric method. Controls showed that the block itself did not affect the excitation. In some experiments response was measured in terms of nerve action currents and no block was used. Even after 30 sec. of recovery, the rheobase is found on the average 27% higher than that of resting nerve, and several minutes are required for the return to normal. The chronaxie, under the same conditions, shows no change or a slight fall.