Intensification of brain injury and blood-brain barrier permeability by short-term hypertension in experimental model of brain ischemia/reperfusion

Arterial hypertension is one of the causes of stroke، and as one of the vasculotoxic conditions intensifies ischemic stroke complications. The aim of the present study was to analyze the effects of short-term cerebral hypertension on ischemia/reperfusion injury and pathogenesis of ischemic stroke. The experiments were performed on three groups of rats (N=36); Sham، control ischemia and hypertensive ischemia. Rats were made acutely hypertensive by abdominal aortic coarctation، and after 8 days، were randomly selected for cerebral ischemia induced by middle cerebral artery occlusion (MCAO) for 60 min followed by 12 h reperfusion. The rats were slaughtered under deep anesthesia for measurement of cerebral injury area by triphenyltetrazolium chloride staining method or blood-brain barrier (BBB) integrity disruption by Evans blue extravasation technique. Arterial pressure was increased >36% in hypertensive rats، and blood flow of the ischemic region was reduced by 80% in the ischemic groups compared with the sham. MCAO induced infarction in large areas of the right hemisphere in hypertensive rats compared with control ischemic rats، and subcortical infarct volume was significantly more in ischemic groups (236±43 vs. 139±25 mm3). MCAO also increased Evans blue extravasations in hypertensive rats (9. 48±2. 03 μg/g) more than non-hypertensive rats (5. 09±1. 41 μg/g). The findings of present study indicate that the short-term hypertension intensifies the ischemia/reperfusion-induced brain injuries. This type of hypertension also causes severe damage in BBB function and enhanced cerebrovascular permeability after brain ischemia.