Histomorphometry on Regenerated Muscle Fiber in the Damaged Striated Muscle

The repair of striated muscle after injury by trauma or chemicals occurs simultaneously by the regeneration of disrupted muscle. Tlthough the efects of various external factors e.g. denervation, irradiation and steroid upon the repair of striated muscle injury has been previously studied, no attention has been focused on the effect of trauma and local anesthetics on the regenearted muscle fiber.

The author induced a constant contusion injury on the calf of rats using Drop-Weight method Lidocaine and/or epinephrine was intramuscularly injected at the site of injure.

The results of morphological and histochemical observation were as follows:

1) The striated muscle showed histological and histochemical evidences of the healing process for 90 days.

2) Formation of myotube appeared on 7th day and decreased on 15th day. Myotube persisted upto 30 days.

3) The cross sectional area of the muscle fibers was measured days 30 and 90. Local anestetic injection groups showed mire muscle fiber atrophy than trauma alone groups. Muscle fibers were significantly more atrophied on day 90 in all types of fiber after injection of mixture of lidocaine and epinephrine and on type B after injection of mixture of lidocaine and epinephrine and in type B after injection of epinephrine compared to control group.

4) Regenerative capacity of the injured muscle piber was correlated with the formation of myotubes.