Refractory period, conduction of trains of impulses, and effect of temperature on conduction in chronic hypertrophic neuropathy

Abstract

The refractory period, the ability to transmit trains of impulses, and the effect of temperature on conduction, have been studied in the sciatic-tibial nerve trunks of Trembler mice, which suffer from a dominantly inherited hypertrophic neuropathy. Both the refractory period of transmission and the relative refractory period were increased in Trembler mice when compared with controls. The nerve trunks of Trembler mice were unable to conduct rapid trains of impulses, and conduction block occurred at rates of stimulation as low as 25 Hz. Cold block occurred at temperatures significantly higher in Trembler nerves than in controls. The conduction velocity increased in an approximately linear fashion in both Trembler and control nerves when the temperature was raised from 20 degrees C to 40 degrees C, and the slopes were not significantly different. The Q10 (27 degrees C-37 degrees C) was 1.5 and 1.6 for control and Trembler nerves respectively. Conduction block was regularly observed in Trembler nerves when the temperature was raised within the physiological range. The abnormalities are related to the pathological changes of chronic demyelination.