Increased ischemia-reperfusion blood flow impairs the skeletal muscle contractile function

Background. The ultimate aim of replantations and transplantations of skeletal muscle is to improve impaired function. The purpose of this study was to examine the contribution of varying durations of ischemia to postischemic blood flow in the skeletal muscle and the contribution of modulation of postischemic blood flow to skeletal muscle function and viability, using an ischemic revascularized hind limb model in rats. Materials and methods. Warm ischemia produced by vascular pedicle clamping was sustained for 90 min, 3 h, or 6 h. Postischemic blood how was measured by a Doppler flowmeter or microsphere technique. In another series of experiments of 3-h ischemia, either saline or N-G-methyl-L-arginine acetate (L-NMMA) was infused for the first 2 h of reperfusion. Postischemic blood flow was also measured. Muscle contractile function and viability were determined after 24 h of reperfusion. Results. Postischemic blood how was significantly increased during the first 10 min of reperfusion in the 90-minute ischemic group and during the first 2 h in the 3-h ischemic group compared with contralateral control blood how. No significant increase in postischemic blood how was noted in the 6-h ischemic group. Postischemic blood flow was significantly decreased by the L-NMMA infusion. Contractile function and viability of the tibialis anterior muscle and contractile function of the gastrocnemius muscle in the L-NMMA group were significantly increased. Conclusion. Reperfusion blood how increased time dependently until 3 h of warm ischemia. Hyperemia deteriorated skeletal muscle contractile function, although it was well preserved by L-NMMA infusion to restrict the postischemic hyperemia. (C) 2001 Academic Press.