EFFECTS OF S-NITROSO-N-ACETYLCYSTEINE ON CONTRACTILE FUNCTION OF REPERFUSED SKELETAL-MUSCLE

The ultimate goal of replantation and microsurgical reconstructive ope rations is to regain or improve impaired function of the tissue. Howev er, the data related to the influence of NO on tissue function are lim ited. This study evaluated the effects of the NO donor S-nitroso-N-ace tylcysteine (SNAC) on contractile function of skeletal muscle during r eperfusion. Forty-nine rats were divided into six groups. The extensor digitorum longus (EDL) muscles in groups I and II were not subjected to ischemia-reperfusion but were treated with a low (100 nmol/ min) or high (1 mu mol/min) dose of SNAC. In groups III-V, the EDL underwent 3 h of ischemia and 3 h of reperfusion and was also treated with low ( 100 nmol/min) or high doses (1 or 5 mu mol/min) of SNAC. Group VI was a phosphate-buffered saline (PBS)-treated control group. Twenty additi onal animals were used to document systemic effects of SNAC and PBS on ly. SNAC or PBS was infused for 6.5 h, beginning 30 min before ischemi a and continuing throughout the duration of reperfusion. Contractile t esting compared the maximal twitch force, isometric tetanic contractil e forces, fatigue, and fatigue half time of the experimental EDL and t he contralateral nontreated EDL. The findings indicate that 1) SNAC do es not influence contractile function of EDL muscle not subjected to i schemia-reperfusion, 2) SNAC significantly protects the contractile fu nction of ischemic skeletal muscle against reperfusion injury in the e arly reperfusion period, and 3) the protective role of SNAC is critica lly dosage dependent; protection is lost at higher doses. The conclusi on from this study is that supplementation with exogenous NO exerts a protective effect on the tissue against reperfusion injury.