Ultraviolet Effects on Refractory Period of Nerve

Abstract

The median giant nerve fiber of the earthworm was subjected to UV irradiation with concomitant electrical stimulation to determine the relative refractory period. A decrease in refractory period, representing an enhancement of activity, was followed by an increase and ultimate block. The results were due to an alteration of the nerve and were not dependent upon concomitant irradiation. The response was dose-dependent, low dose rates producing greater enhancement. Even greater enhancement of activity was obtained by a short exposure at low intensity, after which the nerve was not irradiated.