The effect of adrenergic β(2) receptor agonist on paraplegia following clamping of abdominal aorta

INTRODUCTION: Surgical repair of an aortic aneurysm might be complicated by spinal cord injury and paraplegia. Since β-adrenoreceptor agonists showed neuroprotective effects, the study was designed to investigate the effect of clenbuterol on post-aortic clamping paraplegia and to identify if there is hyperemia associated with paraplegia. MATERIAL AND METHODS: Material and methods: Thirty rabbits were divided into two groups: 15 control and 15 experimental (given clenbuterol 9 mg in drinking water 24 h prior to surgery). All the animals were subjected to laparotomy whereas the abdominal aorta was identified. Using a vascular clamp, the abdominal aorta was clamped just distal to the renal arteries. Abdominal aortic blood flow was recorded with a transonic flow meter. The neurological assessment was made according to Tarlov’s Neurological Scale upon recovering from anesthesia. Anal sphincter tonus and bladder sphincter function were also checked. RESULTS: Four rabbits (2 control and 2 experimental) developed complete paraplegia within 30 min of cross-clamping of the aorta. Of the 13 controls, 77% developed paraplegia, and of the 13 experimental rabbits administered clenbuterol 24 h prior to surgery with 22 min of aortic cross-clamping, 38% developed paraplegia The rabbits which did not develop paraplegia had a minimal increase in aortic blood flow, whereas the rabbits which developed paraplegia had a significant increase in aortic blood flow measurements after aortic decamping. CONCLUSIONS: Post-aortic clamping paraplegia is associated with hyperemia and clenbuterol has a significant neuroprotective effect, obviously by preventing an increase in aortic blood flow following unclamping.