Detection of free radicals by isolated perfusion of the rat brain following hemorrhagic stroke: a novel approach to cerebrovascular biomarker research.

Blood-borne biomarkers are a mainstay of diagnosis and follow-up in many diseases. For stroke, however, no reliable biomarkers have thus far been identified. To remedy this situation, we investigated the usefulness of a modified in situ isolated brain perfusion (IBP) technique for screening potential biomarker candidates. As a proof of concept, the production of reactive oxygen species (ROS) was estimated in a rat model of experimental intracerebral hemorrhage (ICH). After stereotactic infusion of whole blood into the rat striatum, we initiated IBP without intracranial manipulation or discontinuation of cerebral blood flow. To detect ROS, we employed the salicylate trapping method, which involves the hydroxylation of salicylic acid during oxidative stress into dihydroxybenzoic acid (DHBA), and quantification of the latter in venous eluate by using high-performance liquid chromatography. Venous eluate was collected separately from both injured and healthy hemispheres (n=10). Control groups consisted of sham-injured (n=4) and healthy animals (n=3). In animals subjected to ICH (n=10), 50% more 2,5-DHBA was detected in venous eluate on the injured side than in eluate on the contralateral side. Hemorrhagic hemispheres produced more 2,5-DHBA than hemispheres in sham-injured and healthy animals (72 and 110% more 2,5-DHBA, respectively). Isolated brain perfusion combined with salicylate trapping produced data indicating an elevation in the formation of ROS subsequent to ICH. Our findings suggest that isolated in situ brain perfusion is a promising approach to detecting biomarkers of cerebrovascular pathologic conditions.