LIMB ISCHEMIA AND REPERFUSION - RELATIONSHIP OF FUNCTIONAL RECOVERY TO NERVE AND MUSCLE BLOOD-FLOW

The relative importance of nerve versus muscle injury in limb ischemia -reperfusion is poorly understood. We used C-14-butanol tissue distrib ution to measure regional blood flow simultaneously in the proximal an d distal sciatic, the posterior tibial nerve trunk (NBF), and biceps f emoris muscle (MBF) of rats during 3 hours of occlusion of the ipsilat eral iliac and femoral arteries and subsequently for up to 9 days of r eperfusion. Limb motor function was also serially assessed. The contra lateral limbs served as controls. Experimental groups were untreated c ontrol(n = 16); methylprednisolone, 30 mg/kg (0 = 13); the lazaroid U7 4389F, 3 mg/kg (9 = 13); and lazaroid vehicle (0 = 13), IV 15 minutes before occlusion and 15 minutes after reperfusion. Results: One hour a fter occlusion, NBF was -77% of the control value (p < 0.02) but MBF w as unchanged (control NBF 15.2 +/- 3.3, control MBF 6.3 +/- 0.9, units mL.min(-1).100 g(-1)). At both 2 and 21 hours of reperfusion, NBF was double that of control in all groups (p < 0.01); but MBF, which had b een modestly elevated to 10.5 +/- 0.5 at 2 hours (p < 0.01), was alrea dy normal at 21 hours in all groups. During days 5 to 9 of reperfusion , NBF was still numerically elevated (NS); MBF remained at control. Fu nctionally, test limb scores were always grossly abnormal during occlu sion (range: 7.1-8.5, normal = < 2). After 1 hour of reperfusion, all test limb scores were improved versus occlusion (p < 0.001, Wilcoxon r ank-sum), Subsequently, there was gradual improvement in all groups, s cores at 6 days ranging from 1.9 to 2.5. Conclusion: NBF is rapidly an d severely reduced during ischemia. During reperfusion, the hyperemic flow response in nerve is more prolonged than in muscle. Limb dysfunct ion during ischemia and reperfusion may be largely the result of axona l or neuromuscular junction injury or both. Neither of the two treatme nts had effects on blood flow or limb function.