Effects of pH on the response of peripheral nerve to anoxia.

ABSTRACT

PURPOSE/AIM: Changes in pH are not infrequently encountered in clinical situations and can be associated with significant effects on ion channels, mitochondria and axon function. The purpose of this paper is to study the modulatory effects of pH on the anoxic response in peripheral nerve. MATERIALS AND METHODS: A total of 48 rat sciatic nerves were studied in vitro in a perfusion apparatus. Experiments were carried out at 6 pH levels from 6.0 to 7.8. RESULTS: The amplitude of the nerve action potential (NAP) drops more dramatically with repetitive periods of anoxia when the pH is reduced below 6.5. In addition, velocity decreases and duration increases more with each cycle of anoxia at low pH values. Despite these effects of pH on recovery after anoxia, there was no significant effect of pH on the time course of changes during anoxia. During recovery from anoxia, the NAP recovered more slowly when the pH was lowered. CONCLUSIONS: The pattern of changes in amplitude, velocity and duration suggest that they may be due to interference of high hydrogen ion concentrations with sodium and potassium channel function.