[Experimental study on free muscle transplantation--histological changes and functional recovery of transplanted muscles in relation to the duration of ischemia and denervation].

The purpose of this study was to clarify the influence of temporary ischemia and denervation on the characteristics of transplanted muscles.

METHODS

The rectus femoris brevis muscle of white rabbit was used. Under an operating microscope, this muscle was mobilized preserving its feeding vessels, and the innervating nerve was severed at 1 cm proximal to the entrance of the muscle. Six groups were made as follows. Group D: The severed nerve was left as it was. Group S: The nerve was sutured immediately after severance. No treatment was made on the feeding vessels. Group SI: The artery and vein were clamped for 1, 2, 3 and 4 hours (group SI-1, 2, 3 and 4) after nerve repair. The proximal and distal tendon were reattached to their original place in every group. Examination I: Transplanted muscles were examined histologically and histochemically from 48 hours to 6 months. Motor end-plate was one of the targets of observation.

RESULTS

Main patho-histological changes observed on the muscle and motor end-plates at one week were thought due to denervation, and the longer ischemic time caused more severe change in the group SI-3 and 4. Phagocytosis, destruction of muscle fibers and edema in the interstitial tissue were seen in these long ischemic time groups. A few motor end-plates in the group SI-3 and many of them in the group SI-4 were atrophic and their acetylcholinesterase (AChE) activity was low. Reduced nicotinamide-adenine dinucleotide-tetrazolium reductase (NADH-TR) and phosphorylase activity were reduced in all groups at one week. At 3 weeks, muscle atrophy was pronounced and was found earlier in type II fibers than in type I as a result of denervation. Pathological changes such as elongation, atrophy or segmentation and low AChE activity were observed in the motor end-plates of all groups at 3 and 6 weeks. These findings were more pronounced in the group SI-3 and 4. In all groups at 6 weeks, phosphorylase activity was found to be generally low but NADH-TR reaction stained a few regenerated muscle fibers. Although muscle atrophy was still observed at 9 weeks, recovery in size and shape and histochemical reaction was seen in all groups at this stage. These findings became more manifest at 15 weeks and almost normal appearance of muscle fibers was observed at 6 months. Interstitial connective tissue, however, increased, and necrotized muscle fibers were seen extensively in the group SI-3 and 4.(ABSTRACT TRUNCATED AT 400 WORDS)