OPTIMAL PERFUSION CONDITION FOR RETROGRADE BRAIN PERFUSION

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Experiment 1.Dogs were perfused retrogradely via the sagittal sinus and SVC.Cerebral surface blood flow by laser flowmetry was 5.5,9.0,10.1ml/100g/min with driving pressure of 15,25,35mmHg.Cerebral tissue pHi measured photometrically with Neutral Red vital staining was 6.38-6.8,6.73-7.08,6.79-7.16 after 90 minutes of retrograde perfusion with driving pressure of 15,25 and 35mmHg. Tissue blood flow measured with microspheres in the anterior cerebrum/cortex was 2.2/4.0,7.0/12.1 and 8.1/13.6ml/100g/min, respectively. Retrograde brain perfusion with functional driving pressure of 25mmHg or more protects the brain. Although substancial blood flow in the brain tissue was proved in this animal model, there was a hyperfrontality in blood flow and regional pHi. Homogenous brain perfusion should be experimentally established to examine brain edema after retrograde perfusion.Experiment 2.Antegrade very low-flow perfusion (120 minutes) was tested at 20ﾟC to examine the relationship between perfusion pressure, brain tissue blood flow and brain tissue pHi. Brain tissue pHi was maintained high for 120 minutes by the perfusion with flow-rate of 10 and 20ml/kg/min. Cerebral cortex blood flow was larger than 10.2<plus-minus>1.9ml/100g/min when the driving pressure was above 10mmHg. Cerebral cortex pHi was greater than 7.1 when cortex blood flow was greater than 9ml/100g/min. When the cortex blood flow was smaller than this, brain oxygen consumption and cortex pHi decreased while glucose uptake did not simultaneously decrease. This perfusion condition with blood flow less than 10ml/100g/min causes brain acidosis and may cause brain damage. It should be further investigated whether this incomplete brain perfusion protects the brain or not, or paradoxically insults the brai