Infrarenal aortic occlusion in the rabbit to assess the effect of flunarizine in the prevention of ischemic spinal cord injury.

Infrarenal aortic occlusion in rabbits to produce paraplegia is possible in large series and can be achieved without any side-effects of anesthetic drugs. This model was tested for its suitability to investigate the use of calcium-channel blockers, which potentially reduce or prevent ischemic spinal cord damage. In a pilot study 26 rabbits were treated with 0.1 mg/kg Flunarizine i.v. prior to occlusion and 38 animals served as control. Groups were compared where the aorta was occluded for 10, 15, 20, 25 or 30 min. No reduction of paraplegia in the Flunarizine groups was observed, apart from in the 15-min occlusion subset: here the number of unaffected animals was significantly greater (p less than 0.05). At histopathological examination the number of ischemic spinal cord segments was reduced (p less than 0.03). It is concluded that Flunarizine could not reduce the cellular damage of the spinal-cord due to complete and global ischemia after an aortic occlusion interval exceeding 15 min. The narrow interval between potential recovery (15 min) and definite paraplegia (20 min) makes this rabbit paraplegia model less appropriate for testing of calcium-channel blockers which are presumed to have a moderate effect on the reduction of spinal cord ischemia.