Preserved Muscle Function Research Articles

Oral vitamin C attenuates acute ischaemia-reperfusion injury in skeletal muscle

Ischaemia-reperfusion injury (IRI) is caused by endothelial and subendothelial damage by neutrophil-derived oxidants. Vitamin C is an antioxidant which attenuates endothelial injury after IRI. Our aim was to evaluate the effect of oral vitamin C in the prevention of IRI in skeletal muscle. We used a model of cross-clamping (3 hours) and reperfusion (1 hour) of the cremaster muscle in rats. Muscle function was assessed electrophysiologically by electrical field stimulation. Infiltration by neutrophils was determined by the activity of tissue myeloperoxidase (MPO) and tissue oedema by the wet-to-dry ratio. Neutrophil respiratory burst activity was measured in control animals and groups pretreated with vitamin C. IRI significantly decreased muscle function and increased muscle neutrophil MPO activity and muscle oedema. Pretreatment with vitamin C preserved muscle function and reduced tissue oedema and neutrophil infiltration. Neutrophil respiratory burst activity was reduced in the group treated with vitamin C compared with the control group. We conclude that pretreatment with oral vitamin C protects against acute muscle IRI, possibly by attenuating neutrophil respiratory burst activity.

Effects of a hydroxyl radical scavenger, EPC-K1, and neutrophil depletion on reperfusion injury in rat skeletal muscle.

Oxygen free radicals (OFR) and neutrophils are potent sources of reperfusion injury. We compared the effect of EPC-K1, a new OFR scavenger, and neutrophil depletion on the reperfusion injury in skeletal muscle, using an ischemic revascularized hindlimb model in rats. Warm ischemia, produced by vascular pedicle clamping, was sustained for 4 h. After 24 h of reperfusion, muscle function and damage were evaluated in 4 groups: a sham operation group, a control study group, a group treated by EPC-K1 (EPC group), and a group that received nitrogen mustard to induce neutropenia (NM group). Both the EPC and NM groups had limited muscle damage compared to the control group. The EPC group preserved muscle function significantly better than the control group and the mean isometric tetanic tension in the EPC group appeared to be higher than that in the NM group. Furthermore, levels of lipid peroxides in muscle and serum, and muscle edema in the EPC group, were significantly lower than in the NM group. Histological examinations supported these results. These findings suggest that limiting OFR generation by EPC-K1 in the early phase of reoxygenation is more potent than depletion of neutrophils in reducing reperfusion injury.

Modified pectoralis major myocutaneous flap with partial preservation of the muscle: a study of 55 cases.

The results of a technical modification of the pectoralis major myocutaneous flap are presented in which the clavicular bundles, the first two or three sternocostal bundles, and the lateral border of the muscle were preserved. The flap was delivered into the neck through a subclavicular tunnel. The procedure was performed in 55 patients, with a bilateral simultaneous flap used in one. Four instances of flap necrosis occurred, although it was felt that they were not related to the modified technique, and no damage to the subclavian vessel occurred. In the first 25 flaps, we did not identify the neurovascular bundle supplying the preserved musculature. Eighteen of these flaps were evaluated, and atrophy was encountered in 10. Of the latter 31 patients, only one suffered atrophy of the sternocostal bundle. The technical modification of preserving part of the muscle and its neurovascular supply is especially important in manual workers. Twenty-eight of 38 patients with preserved muscle function at the donor site were manual workers, and 10 of them returned to normal activity. None of the patients who developed atrophy of the pectoralis major muscular remnant was able to return to work within 1 year or longer after treatment. In the successful cases, there were no functional sequelae of the arm, visible depressions in the infraclavicular area, or loss of the anatomic configuration of the anterior axillary line.