EXPERIMENTAL STUDY ON INFLUENCE OF MUSCLE TENSION TOWARDS THE FUNCTION OF THE SKELETAL MUSCLE FOLLOWING ITS REINNERVATION

Objective To investigate the influence of tension on the function of the denervated skeletal muscle after its reinnervation. Methods Fifty-four Sprague-Dawley ( SD ) rats were randomly divided into 3 groups. The left gastrocnemius muscles of the rats were dissected with only the neurovascular pedicles intact; the tibial nerves were cut and immediately repaired by epineurial suture. Then the Achilles tendons were isolated and treated accordingly; the Achilles tendon was lengthened by 0.5cm in lengthened group, shortened by 0.5cm in shortened group and left alone in normal (control) group. In the 2nd, 4th and 8th week after operation, the isometric twitch contractile force of both the right and the left gastrocnemius muscles were measured; specimens were taken from gastrocnemius muscle for histological study by light microscope. Results In comparison between the groups, the gastrocnemius muscles in the shortened group showed less severe muscle atrophy and connective tissue proliferation, bigger diameter and cross section dimension of the muscle fiber and greater isometric twitch contractile strength of the bilateral gastrocnemius muscles than those in the normal and lengthened groups in all the postoperative periods. Coneluaion A proper high tension of the muscle may improve the function of the denervated skeletal muscle after its reinnervation.