Contralateral Leg as a Control During Skeletal Muscle Ischemia-Reperfusion¹

Background: Recent data demonstrated that hind limb ischemia induces skeletal muscle mitochondrial dysfunctions. Improvement of such metabolic myopathy improves patient's symptomatology, supporting the development of experimental models focused on mitochondrial function analysis. However, although the nonischemic contralateral leg is often used as a control during unilateral leg ischemia, whether it might be useful when assessing ischemia-induced mitochondrial dysfunction remains to be investigated. Materials and Methods: Both ischemic (IR) and nonischemic contralateral legs (CTL) of rats (n=13) submitted to 5 h ischemia induced by a rubber band tourniquet applied on the root of the hind limb were studied and compared to that of sham-operated animals (SHAM, n=13). Maximal oxidative capacities (V_max) and complexes I, II and IV activities of the gastrocnemius mitochondrial respiratory chain were determined, using glutamate-malate, succinate (Vs) and TMPD-ascorbate (V_TMPD) substrates. Results: V_max was decreased in IR (4.6±0.4 μM/min/g dry weight) compared to both SHAM and CTL muscles (8.5±0.5 and 7.1±0.4 μM/min/g dry weight, -46% and -36%, P<0.001,respectively). V_S and V_TMPD were reduced in IR muscle (-56% and -48% for V_S; and -25% and -24% for V_TMPD, P<0.001) as compared to SHAM and CTL). V_S and V_TMPD were similar in SHAM and CTL muscles. Conclusions: Five hours ischemia-reperfusion significantly impaired complexes I, II and IV of the ischemic skeletal muscle mitochondrial respiratory chain. Interestingly, only V_max was slightly altered in the contralateral leg, supporting that the nonischemic leg might be used as a control when assessing mitochondrial function in the experimental setting of unilateral hind limb ischemia.