ABSTRACT
BACKGROUND: It has been reported that the ischemia preconditioning (IPC) had credible protective efficiency on ischemic injury of the spinal cord during aorta operation, but the mechanism of the protective efficiency of IPC had not been clarified.OBJECTIVE: To study the protective effects of repetitive IPC on ischemic injury of spinal cord and its mechanism in rabbits.DESIGN: A completely randomized controlled study based on the experimental animals.SETTING: Department of anesthesiology in a university hospital.MATERIALS: The experiment was completed in the Department of Anesthesiology, Renmin Hospital, Wuhan University during September and December 2002. Twenty-four Japanese rabbits were randomly and double-blindly divided into sham-operation group, ischemia-reperfusion group and IPC group with 8 rabbits in each group.INTERVENTIONS: In sham-operation group, abdominal aorta was not clamped. Spinal cord ischemia was induced by infra-renal aortic cross-clamp for 45 minutes in ischemia-reperfusion group. Before the 45 minutes ischemia, the rabbits in the IPC group underwent four cycles of ischemia preconditioning, i.e. clamping abdominal aorta for 5 minutes then reperfusion for 5 minutes.MAIN OUTCOME MEASURES: The concentrations of calcium, magnesium, copper and zincum in spinal cord were measured in the 7th day after operation. Postoperative neurological function, EMG of rear limb, and spinal cord histopathological changes were assessed in all groups after operation.RESULTS: The concentrations of calcium and copper in spinal cord in ischemia-reperfusion group were significantly higher than those in sham-operation group( P ＜ 0. 05 or 0. 01 ), but magnesium and zincum significantly lower( P ＜ 0. 05). Compared with IPC group, calcium in ischemia-reperfusion group was significantly higher( P ＜ 0.01 ), but zincum significantly lower( P ＜ 0.01 ) . The neurological function and histopatholohical changes in ischemia-reperfusion group were much lower than those in sham-operation group and IPC group ( P ＜ 0.05 or P ＜ 0.01) . And there was significantly worse change of EMG in ischemia-repeffusion group than that in IPC group(P ＜ 0.01).CONCLUSION: Repetitive ischemic preconditioning can protect rabbit spinal cord from ischemia reperfusion injury quickly, and one possible reason for its protective effect is to maintain the balance of calcium, magnesium,copper and zincum in ischemic region.
ABSTRACT
Objective To investigate the effect of propofol on expression of cyclinD1 and apoptosis in spinal cord neurons induced by ischemia-reperfusion (I/R) .Methods Sixty male Wistar rats weighing 200-250 g were randomly divided into 2 groups ( n = 30 each): group A I/R and group B propofol + I/R. The animals were anesthetized with 7% chloral hydrate 6 ml?kg-1. The abdomen was opened and the abdominal aorta was clamped distal to the left renal artery for 20 min. The aortic cross clamp was then released to allow reperfusion. In propofol group propofol 100 mg?kg-1 was administered intraperitoneally (IP) during the operation. Neurologic function was assessed using Taylor scale (0 = unable to move hind limbs, 4 = normal function) at 6 h after operation and on postoperative day 1, 2, 3, 7 (n = 6 at each time point) . The animals were killed after neurologic function evaluation and the spinal cord was removed for microscopic examination, detection of apoptosis in the spinal cord neurons ( TUNEL) and determination of cyclinD1 expression (immuno-histochemistry) . Results The histo-pathological damage to the neurons was significantly lighter, the neurological function better and the apoptotic index and the cyclinD1 expression were significantly lower in propofol group than in I/R group. Conclusion Propofol protects spinal cord against I/R injury by reducing neuronal apoptosis through down-regulation of cyclinD1 expression.