Abstract: ObjectiveTo observe effects of intravenous magnesium sulfate (MgSO 4) administration on ischemia reperfusion injury of the spinal cord in rabbits.MethodsNew Zealand White rabbits (n=27) were randomly divided into the group A (treated with MgSO₄), group B (treated with saline) and group C (sham group) with 9 animals in each group. Ischemic model was established with midline laparotomy and clamping the aorta just distal to left renal artery and proximal to aortic bifurcation for 30 min followed by a reperfusion period of 48 h. Animals were treated with 0.25 ml/kg/h MgSO₄ intravenous infusion in group A, treated with similar volume of saline as control in group B, and were anesthetized and subjected laparotomy without aortic occlusion in group C. Somatosensory evoked potentials (SEP) were monitored before ischemia, during ischemia and in the first 60 min of reperfusion. The neurological outcome was clinically evaluated up to 48 h post ischemia, and motor function was scored. The animals were sacrificed two days post ischemia, and spinal cords were processed for histopathological examination.ResultsSEP amplitudes and latencies in group C did not change during the procedures and all animals recovered without neurological deficits. The waves disappeared in group B and reduced to 29% of the initial amplitude at the end of the ischemia in group A. After 60 min reperfusion, SEP amplitudes returned gradually to 74% and 49% of the initial amplitude respectively (P<0.01) in groups A and B. The N1, P1 latencies returned gradually to (28.9±1.9) ms, (57.3±3.2) ms in group A and (30.7±0.9) ms, (61.2±2.9) ms in group B (P<0.05). The average motor function score in group A was significantly higher than that in group B at 24 h and 48 h after reperfusion (P<0.01).ConclusionMgSO₄ intravenous infusion may relieve spinal cord injury and preserve neurological function in transient spinal cord ischemia in rabbits.

Key words: magnesium sulfate, spinal cord injury, ischemia reperfusion, somatosensory evoked potentials (SEP)