The influence of inactivity on membrane resting conductances of rat skeletal muscle fibres undergoing reinnervation.

The role of activity in the maintenance of the normal component resting conductances of skeletal muscle fibres has been evaluated in vitro in rat extensor digitorum longus muscle during reinnervation from 2 to 40 days (a) after crushing of the peroneus nerve and (b) after local application of tetrodotoxin (TTX) to the crushed nerve. Whereas membrane conductances were regained after crushing alone, they were not completely restored when impulse propagation was blocked with TTX. It is concluded that nerve trophic factors are of primary importance in the control of muscular membrane conductances, and that transmission at the endplate and the muscle usage triggered by it have a minor but significant effect.