Passive Exercise and Reinnervation of the Rat Denervated Extensor Digitorum Longus Muscle after Nerve Crush

Abstract

Denervated extensor digitorum longus muscles of Wistar rats were passively exercised for 4 days (2 h/day) after peroneal nerve crush 1 cm from the muscle. Isometric contractile properties and end plate ultrastructure were measured 11 days post crush. No significant differences were observed in tension characteristics between the exercised and non exercised muscles on day 11. However, the postsynaptic area of end plates for exercised muscles were closer in size to controls than those for the non exercised ones. In addition, the end plates from the exercised muscles exhibited increased numbers of axonal sprouts and terminals than non exercised muscles. These results demonstrate that denervated muscles exercised 4 days before reinnervation can preserve the structure of the end plate as well as enhance reinnervation and sprouting at these end plates after 11 days of denervation.