Role of veins and cerebral venous pressure in disruption of the blood-brain barrier.

The goal of this study was to determine whether increases in cerebral venous pressure contribute to, and may account for, disruption of the blood-brain barrier during acute hypertension and hyperosmolar stimuli. We studied the relation between pial venous pressure and disruption of the blood-brain barrier during acute arterial hypertension, superior venae cavae occlusion, and superfusion with hyperosmolar arabinose. Sprague-Dawley rats were studied using intravital fluorescent microscopy and fluorescein-labelled dextran (mol. wt. = 70,000). Disruption of the blood-brain barrier was characterized by the appearance of microvascular leaky sites and quantitated by the clearance of fluorescein dextran. We measured pressure (servo null) in pial arterioles and venules 40-60 micron in diameter. Acute hypertension, occlusion of the superior venae cavae, and hyperosmolar arabinose produced leaky sites primarily in venules. Acute hypertension increased arteriolar pressure and also venular pressure, from 7 +/- 1 (mea...