Nitric oxide synthase expressions in mice skeletal muscle subjected to ischemia/reperfusion injury

Nitric oxide synthase (NOS) expressions in skeletal muscle subjected to ischemia/reperfusion (I/R) were studied using a hind limb tourniquet ischemia model in mice. A rubber band was applied to a hind limb for 3 h under isoflurane anesthesia followed by 1 or 4 h of reperfusion. Increased NADPH diaphorase activity and NOS immunoreactivity were histochemically detected in the cells of muscle that had been subjected to I/R. The results of RT-PCR of the muscle subjected to I/R showed that NOS mRNA expressions were not significantly increased until 4 h after the start of reperfusion. Since there was no significant difference between histochemical findings or between water contents of the hind limbs or organs in interleukin (IL)-6-deficient mice and the wild-type mice, IL-6 may not be involved in the early stage of I/R muscle injury such as that in this model. O(2)(-) production in the cells of muscle that had been subjected to I/R was observed using an in situ detection method with hydroethidine, and the O(2)(-) was inhibited by intravenous administration of L-NAME or L-NMMA, but not L-NIL, 30 min before tourniquet release. Further study is needed to evaluate the role of O(2)(-) produced by constitutive NOS in muscle subjected to I/R in the pathophysiology of tourniquet shock.