Oxygen Free‐Radical Reduction of Brain Capillary Rubidium Uptake

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Abstract
Free radicals are proposed to play a role in the injury following cerebral ischemia in which cerebral edema is a prominent feature. To determine whether free radicals might alter the movement of ions and water across the blood‐brain barrier, we examined their effect on brain capillary transport. Rat brain capillaries were isolated, incubated with a system that generates free radicals, and various capillary transport systems were studied. Rubidium uptake was reduced 74% whereas rubidium efflux, glucose transport, and capillary water space were unchanged. The results following the addition of radical scavengers indicated that hydrogen peroxide or a related free radical was the toxic species. These data suggest that free radicals can impair capillary endothelial cell mechanisms that help maintain homeostasis of electrolytes and water in brain.