The protective efficacy of magnolol in hind limb muscular ischemia- reperfusion injury. (II) Free radicals and neutrophils are potent sources of ischemia reperfusion injury. We compared the effect of magnolol, a free radical scavenger, and antiinflammation on the on the reperfusion injury in skeletal muscle, using ischemia reperfusion hind limb model in rats. In our study, male Spraque-Dawley rats were randomizied into 3 groups : (A) a control group, (B) a group pretreated by magnolol 0.3 mg╱kg, (C) a group pretreated by magnolol 1.0 mg╱kg. Both the (B) and (C) groups had limited muscle damage compared to the control group. 2 h of ischemia were introduced in right hind limb by application of a elastic rubber tourniquet to the proximal thigh. After 22h of reperfusion, muscle damage was evaluated. Muscle damage evaluated by H&E stain, measurement of NOx metabolites, LDH activity and myeloperoxidase (MPO), GSH activity were analyzed after 22 h after reperfusion. When compared to the control group, both given magnolol groups had limited muscular damage. The magnolol (1.0 mg╱kg) group attenuated muscular inflammation and edema significantly better than magnolol (0.3 mg╱kg) group and the control group. Furthermore, serum level of NOx and muscular level of LDH, MPO in the 1.0 mg╱kg magnolol group (NO: 2.9 +- 1.1 ; LDH：106.2 +- 15.5; MPO：2.0 +- 0.5 U╱100μg ) were significantly lower than 0.3 mg╱kg magnolol group (NO:3.8 +- 0.8 ; LDH：189.5 +- 14.6; MPO：4.2 +- 1.5 U╱100μg ) and control group (NO: 5.9 +- 1.5 ; LDH：216.8 +- 18.2; MPO：8.0 +- 0.8 U╱100μg ) after 22 h of reperfusion. The GSH╱GSSG in the C group (1.24 +- 0.51) were significantly higher than the B group (0.44+- 0.16) and the A group (0.16+- 0.06) after 22 h of reperfusion. Histopathological examinations of the gastrocnemius muscle also supported these results. These findings suggest that magnolol may provide dose-dependent and significantly protective efficacy in rat hind limb muscle ischemia reperfusion injury.
