Effects of hemodilution on neurological injury and cerebral amino acid content after circulatory arrest during profound hypothermia in rats

摘要

To investigate the effects of different degrees of hemodilution on neurological injury and amino acid content in different brain areas after deep hypothermic circulatory arrest (DHCA).Methods Forty-eight male adult SD rats weighing 400～450 g were randomly divided into 4 groups (n=12 each):group Ⅰ Hct 10%(H1);group Ⅱ Hct 20% (H2);group Ⅲ Hct 30%(H3) and control group (C).All animals except those in control group underwent DHCA at 18℃ for 90 min (includinhg cooling and rewarming) under general anesthesia with fentanyl,ketamine and droperidol.Different degrees of hemodilution were accomplised by changing the composition and volume of priming solution used in cardiopulmonary bypass (CPB).Hct was determined before,at the initiation of CPB and beginning of rewarming.PaO2,pH and blood lactate of arterial blood and SO2 of venous blood from internal jugular vein (SjvO2) were determined at the beginning and end of cooling and rewarming.The animals were killed and brains removed after recovery of circulatory function for the count of injured neurons and detemination of glutamate (Glu),aspartate (Asp),glycine (Gly),γ-aminobutyric acid (GABA) and taurine (Tau) contents in cortex,hippocampus and thalamus.Results The number of injured neurons in hippocampus and parietal cortex were significantly smaller in Hct 30% group than in the other two groups (P<0.05).The contents of the five amino acids in hippocampus and parietal cortex were all increased after DHCA.The Glu,Asp and Gly contents in hippocampus and parietal cortex were significantly lower in Hct 30% group than in the other 2 groups (P<0.05).There was no significant difference in GABA and Tau contents among the 3 groups.Conclusion Hemodilution at Hct 30% attenuates the neuronal injury after DHCA.The inhibition of the release of the excitatory amino acids in the brain may be involved in the mechanism of neuronal protection.13 refs,1 fig,3 tabs.