Effect of intracerebral and subdural hematomas on energy-dependent transport across the blood-brain barrier

Although both intracerebral and subdural hematomas induce brain edema, prev ious studies have indicated that they may have different cerebrovascular ef fects. Our own investigations have demonstrated that while subdural hematom as (SDH) are associated with ischemia this is not the case following intrac erebral hematomas (ICH). Previous studies have demonstrated a decrease in e nergy-dependent transport of glutamine across the blood-brain barrier (BBB) following focal cerebral ischemia. The present study investigates this fur ther by examining the effects of SDH, ICH, and intracerebral thrombin injec tions, an agent involved in ICH-induced injury, on blood to brain glutamine transport. The injection of 200 mu L of blood into the subdural space indu ced a marked reduction in glutamine transport (K-i, influx rate constant) i nto the cerebral cortex at 4 and 24 h following SDH (sham, 105 +/- 4% of co ntralateral 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 a reas following SDH. Following ICH (200-mu L 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 differe nces in the effects of ICH and SDH on BBB function.