Mechanically provoked insertional activity before and after nerve section in rats.

Mechanically provoked insertional activity was recorded at intervals prior to and through the development of positive sharp waves and fibrillation potentials in the gastrocnemius and soleus muscle group of eight male Wistar rats in the normal state, and after the sciatic nerve was cut at the sciatic notch. The wave form and duration of injury potentials were analyzed. Positive sharp waves were found to occur prior to the development of fibrillation potentials. No significant increase in the duration of injury potentials was noted prior to the development of positive sharp waves and fibrillation potentials. The frequent clinical use of the term "prolonged" or "increased" insertional activity as an abnormal finding in a continuum to positive sharp waves is questioned.