Abnormalities of the blood-brain barrier in global cerebral ischemia in rats due to experimental cardiac arrest.

The aim of the study was to characterize the impact of global cerebral ischemia resulting from cardiac arrest on the BBB permeability. Survival time of experimental animals after 3.5, 5 or 10 min ischemia range from 3.5-10 min to 24 h. Vascular permeability was evaluated with horseradish peroxidase (HRP). BBB disturbances were of biphasic nature. In the first phase, appearing immediately after ischemia and persisting till 1st postischemic hour, HRP extravasation involved mainly venous site of microcirculation and was limited to the cerebral and cerebellar cortex and the central periventricular structures. The second phase covering the period between 6 and 24 h after resuscitation was characterized by random HRP leakage in all the CNS structures. HRP penetrated through increased microvesicular and canalicular endothelial systems, through interendothelial junctions and via disintegrated endothelial cells. Distribution and perivenous localization of BBB changes in early phase suggests their connection with venostasis resulting from cardiac arrest. The second phase seems to be pathogenetically related with the consequences of the ischemic process.