Role of adrenergic activity in ischemic brain edema

Thirty male Wistar rats, weighing 200 to 300 g, were used for this study. During a 3- to 4-min period, 300 micrograms of 6-OHDA was injected stereotactically into the right lateral ventricle. The same amount of saline was injected into the ventricle for the control group. Seven days after this procedure, the right common carotid was occluded with a clip and 4 to 6 ml of blood was removed from the external jugular vein to reduce the blood pressure. The clip was removed in 2 hr, and blood flow was maintained for 1 hr. The SG of cerebral tissue was measured according to the method of Marmarou et al. The disruption of BBB was examined by Evans blue injection, and the brain tissue was also examined by electron microscopy. Rats with 6-OHDA treatment had brain edema although the control group had no edema. We suggest that the depletion of brain NA could cause a disturbance in cerebral microvascular tone and could make cerebral blood vessels more vulnerable to the decreased CBF when followed by restoration of the blood flow.