Induced hypertension during restoration of flow after temporary middle cerebral artery occlusion in the rat: effect on neuronal injury and edema.

The effect of hypertension instituted during restoration of flow after focal ischemia was studied. After the middle cerebral artery (MCA) of 12 rats was occluded for 2 hours, the ligatures were released and flow was restored for a period of 2 hours. In the control group, mean arterial pressure (MAP) was not manipulated. In the hypertensive group, the MAP was elevated by 25-30 mm Hg immediately after reestablishment of MCA patency. The area of neuronal injury, determined by 2,3,5-triphenyltetrazolium staining, was significantly smaller in the hypertensive group. Specific gravity, determined by microgravimetry, did not differ between groups. The data demonstrate that modest hypertension, when induced during reperfusion after 2 hours of MCA occlusion, reduces neuronal injury and does not exacerbate edema formation.