Magnesium sulfate for spinal cord ischemia-reperfusion injury in rabbits

Lihong FAN; Bin CHENG; Yong LI

ABSTRACT

BACKGROUND:

It has been reported that magnesium sulfate(Mg2SO4)treatment has a satisfactory effect on brain ischemia-reperfusion injury, but its effect on spinal cord ischemic injury remains unclear.

OBJECTIVE:

To evaluate the effects of intravenous administration of Mg2SO4 on spinal cord ischemia-reperfusion injury and further probe into its mechanism.

DESIGN:

Randomized controlled repeatedly measuring design based on the experimental animals.

SETTING:

Central research laboratory of a university hospital.MATERIALS The experiment was conducted in the Central Research Laboratory, Medical College of Xi' an Jiaotong University from April 2003 to June 2004. Twenty-seven New Zealand white rabbits with body mass of 1.9to 2. 5 kg were included. The rabbits were randomly divided into Mg2SO4group, normal saline group and sham-operation group with 9 rabbits in each group.

METHODS:

The lower segment of the kidney under abdominal aorta was occluded for 30 minutes and 48-hour reperfusion was performed to establish ischemia-reperfusion model of lumbosacral segment of spinal cord. Mg2SO4group (Group A, n = 9) received Mg2SO4 at the dose of 0. 25 mL/kg per hour throughout this procedure; the same volume of saline solution was used in normal saline group(Group B, n=9) . Animals of sham-operation group (Group C, n = 9) were anesthetized and received laparotomy without aortic occlusion. The somatosensory evoked potential(SEP) was detected before ischemia, 30 minutes after ischemia, and 1, 2, 8, 16 and 24 hours after reperfusion. Motor function score was assessed in Mg2SO4 and saline groups 24 and 48 hours after reperfusion. After reperfusion for 48 hours, the animals were killed and histopathological test was performed on the spinal cord.MAIN OUTCOM

MEASURES:

Motor function score, SEP monitoring and spinal histopathological test.

RESULTS:

The latency of SEP(Nt) was markedly longer 30 minutes after ischemia in Mg2SO4 group. It was obviously recovered during the first two hours after reperfusion compared with during ischemia, but was obviously prolonged after that. Waveform disappeared 30 minutes after ischemia in normal saline group. SEP amplitudes and latencies in sham-operation group did not change remarkably during the procedures and all the animals recovered without neurological deficits. At each reperfusion time point, the recovery of SEP(N1) latency was better in Group A than that in Group B( P ＜ 0.05). The average motor function score at 24 hours and 48 hours after reperfusion was significantly higher in Group A[ (3.7 ±0.5) and(3.4 ±0.7) points] than that in GroupB [(3.0±0.7) and (2.6±0.9) points](P ＜0.05). The normal nerve cell counting of spinal cord 48 hours after reperfusion in Mg2SO4 group(23. 4 ± 3. 4) was significantly higher than that in saline group (12.3 ±3.2)(P ＜ 0.01).

CONCLUSION:

Intravenous Mg2SO4 administration may reduce spinal cord injury and preserve neurological function in transient spinal cord ischemia in rabbits.