Influence of L-arginine on cerebral oxygen metabolism during deep hypothermic circulatory arrest in dogs

Objective To investigate the effect of L-arginine (L-arg) on cerebral oxygen metabolism and ultrastructure during deep hypothermic circulatory arrest (DHCA) in experimental dogs. Methods Fifteen healthy adult mongrel dogs with both sexes, weighing (14.7±2.4)kg, were randomly divided into three groups (n=5): sham treated group, L-arg pretreated group (100mg/kg L-arg was given 60min before circulation arrest), L-arg and 7-Ni combined treated group (100mg/kg L-arg and 25mg/kg 7-Ni were given 60min before circulation arrest). Extracorporeal circulatory was established routinely, and DHCA commenced when the nasopharyngeal temperature was reduced to 18℃, then reperfusion began after 90min of DHCA. SjvO2, NO in plasma were measured 30min before DHCA and 0,45,90min after DHCA commencement and 60min after rewarming. The ultrastructural changes of cortex and hippocampal gyrus were also been observed with transmission electron microscope after the dogs were executed. Results Compared with sham-treated group, L-arg pretreatment combined with 7-Ni or not increased NO content in plasma, SjvO2 during DHCA, improved cerebral oxygen metabolism and reduced brain ultrastructural injury. There was a positive correlation between NO conten in plasma before arrest and SjvO2 after arrest (r=0.679,P=0.005). Conclusion L-arg pretreatment has cerebral protective effects and can improve cerebral oxygen metabolism during DHCA. Key words: Extracorporeal circulatory;  Deep hypothermic circulatory arrest;  L-arginine;  7-nitroindazole;  Jugular venous oxygen saturation