[Age-related excitability of the muscle after the sciatic nerve blockade in rats]

In adult (8 weeks) and old (24 weeks) white rats early postdenervation changes (in 12 and 24 hours after nerves squeezing) of bioelectric activity of gastrocnemius muscles were studied using electrophysiological methods. Parameters of the activity were: a threshold, chronaxy during direct and indirect muscle irritation; amplitude, duration, the latent period of action potential (AP), an amplitude of AP during increasing stimulation and during dual irritations. It is established that the changes in these parameters in group of adult animals are considerably more pronounced and directed to the increase in excitability of the denervated muscle. In the group of old animals these changes were absent or they were considerably smaller. It is suggested that the cause of more pronounced postdenervated changes in adult animals is a higher speed of axoplasmic transport of the substances in the motor fibers of a isciatic nerve.