Effect of Intracerebral and Subdural Hematomas on Energy-Dependent Transport Across the Blood-Brain Barrier

Abstract

Although both intracerebral and subdural hematomas induce brain edema, previous studies have indicated that they may have different cerebrovascular effects. Our own investigations have demonstrated that while subdural hematomas (SDH) are associated with ischemia this is not the case following intracerebral hematomas (ICH). Previous studies have demonstrated a decrease in energy-dependent transport of glutamine across the blood-brain barrier (BBB) following focal cerebral ischemia. The present study investigates this further by examining the effects of SDH, ICH, and intracerebral thrombin injections, an agent involved in ICH-induced injury, on blood to brain glutamine transport. The injection of 200 μL of blood into the subdural space induced a marked reduction in glutamine transport (K _i , influx rate constant) into the cerebral cortex at 4 and 24 h following SDH (sham, 105 ± 4% of contralateral cortex; SDH 4 h, 63 ± 5%, p < 0.01; SDH 24 h, 47 ± 12%, p < 0.05). There were no significant changes in glutamine K _i in subcortical areas following SDH. Following ICH (200-μL clot); however, there were only modest decreases in glutamine K _i in subcortical areas (sham, 98 ± 2% of right cortex; ICH 4 h, 91 ± 5%, p < 0.01; ICH 24 h, 91 ± 2%, p < 0.05). Intracerebral injection of thrombin (5U) had minimal effect on glutamine K _i , in subcortical areas, at 4 h and induced a modest decrease in transport at 24 h (sham, 98 ± 2% of right cortex; thrombin 4 h, 98 ± 2%; thrombin 24 h, 86 ± 2%, p < 0.05). The present studies demonstrate marked differences in the effects of ICH and SDH on BBB function.