[Role of endogenous norepinephrine and effects of alpha- and beta-blockers in experimental spinal cord compression injury].

The changes in spinal cord micro-circulation were investigated after administering alpha- and beta-blockers to rabbits with acute spinal cord injury. Immediately after the 8th thoracic spinal cord was injured by applying pressure with a weight (50 g) for 1 minute, an alpha or beta-blocker was injected into the subarachnoid space of the injured region of the spinal cord. Spinal cord edema, blood flow, vascular permeability, and the mean arterial pressure were compared between the groups treated with each agent and the control group. One hour after the injury, the water content of the spinal cord was significantly lower in the phenoxybenzamine-treated group than in the control group. After 6 hours, however, no significant difference was observed between these two groups. The spinal cord blood flow was higher in the phenoxybenzamine-treated group than in the control group until 6 hours after the injury. These results suggest involvement of norepinephrine in the formation of edema at the early stage of spinal cord injury.