Effects of retrograde perfusion of the brain with combined drug therapy after focal ischemia in rat brain.

Abstract

The ischemic edema associated with blood-brain barrier permeability changes and the excess production of free radicals are serious complications in prolonged cerebral ischemia. We examined the efficacy of transvenous perfusion of the brain, starting treatment 5 hours after occlusion of the middle cerebral artery for a period of 2 hours in rats with the combined agents mannitol (10 ml/2 hr) and dexamethasone (1 mg/2 hr) to counter edema and verapamil (0.05 mg/kg/2 hr) for vasodilation. In experiment 1, blood-brain barrier permeability changes were examined in five groups with six rats each: group C rats underwent 7 hours of middle cerebral artery occlusion with no treatment; group V, treatment with verapamil alone; group VD, treatment with verapamil and dexamethasone; group VM, treatment with verapamil and mannitol; and group VDM, treatment with verapamil, dexamethasone, and mannitol. In experiment 2, we examined local cerebral blood flow, ischemic tissue damage volume, and water content of cerebral hemispheres in two groups of 16 rats each subjected to the same treatment as groups C and VDM rats in experiment 1. There was a significant reduction of blood-brain barrier permeability changes in the ischemic cortex of rats in group VDM compared with rats in the other groups. In the group undergoing transvenous perfusion of the brain with the three combined agents, there was a significant improvement of cerebral blood flow (39-58%, p < 0.05) in the ischemic cortex and reduction of ischemic cerebral damage volume (22%, p < 0.01) and water content of the ischemic hemisphere (p < 0.05) compared with the control group. The therapeutic approach using combined agents is effective treatment when initiated within 5 hours of focal cerebral ischemia in rats.