Protective effect of intrathecal ketorolac in spinal cord ischemia in rats: a microdialysis study

BACKGROUND: The prevention of ischemic paraplegia after thoracoabdominal aortic surgery is challenging for both anesthesiologists and surgeons. In a previous study, we showed that intrathecal ketorolac pre-treatment protects rats against ischemic spinal cord injury. In the present study, using a microdialysis method, we investigated whether this neuroprotective effect was related to changes in the spinal cord release of nitric oxide (NO) or the excitatory amino acids (EAAs) aspartate and glutamate. METHODS: Rats were randomized to receive either intrathecal saline or ketorolac 60 microg (10 rats per group), 1 h before spinal cord ischemic injury induced by balloon inflation of a 2F Fogarty catheter in the thoracic aorta with maintenance of the proximal arterial blood pressure at 40 mmHg for 11 min, followed by reperfusion. Another 10 animals were used as the sham-operated control group. Ischemic injury was assessed by hind limb motor function. Cerebrospinal fluid dialysates were collected at baseline (before ischemia) and at 1, 2, 3, 4, 6, 12 and 24 h after the start of reperfusion, and were analyzed for EAAs using high-performance liquid chromatography and for NO metabolites using an NO analyzer. RESULTS: The results showed that intrathecal ketorolac attenuated spinal cord ischemic injury. Dialysate concentrations of NO and EAAs were increased after spinal cord ischemia, and this effect was inhibited by intrathecal administration of ketorolac. CONCLUSIONS: The results of this study suggest that the neuroprotective effect of intrathecal ketorolac in spinal cord ischemia in rats may be caused by a decrease in the spinal cord release of NO and EAAs.