深低温停循环脊髓损伤的微透析研究

目的运用微透析技术观察猪深低温停循环过程中脊髓神经细胞间液中的各种物质变化，探讨脊髓损伤的分子机制。方法6只小型香猪，于腰2段脊髓中植入微透析针。建立体外循环，并行循环降温30min至直肠温度为20℃，停循环60min，复温和并行循环120min。在固定时间点采集微透析样本，检测氨基酸和能量代谢物质含量，观察变化趋势。结果停循环期间丙酮酸明显降低，乳酸／丙酮酸比值达到高峰。复温后葡萄糖、乳酸、丙酮酸和甘油显著升高。降温时谷氨酸和γ-氨基丁酸明显升高。天门冬氨酸、牛磺酸和甘氨酸在复温时升高明显。结论停循环过程中，神经元细胞的能量代谢被明显抑制。复温中能量代谢率有所恢复，细胞处于高糖、高乳酸的环境中。降温时谷氨酸和γ-氨基丁酸升高，复温中天门冬氨酸、甘氨酸和牛磺酸均显著升高，可能与脊髓损伤有关。

Microdialysis Study of the Spinal Cord during Deep Hypothermic Circulatory Arrest in a Porcine Model

OBJECTIVE To investigate the changes in energy - related metabolites and the concentration of amino acid in spinal cord during deep hypothermic circulatory arrest. And discuss the mechanism of spinal cord injury. METHODS Microdialysis probe was inserted into the lumbar spinal cord of six pigs respectively. They were cooled to 20℃ by cardiopulmonary bypass （CPB）. CPB was established by right atria and aorta cannulation. The rental temperature was cooled to 20℃ by 30 minutes bypass. Then the circulatory arrest was kept for 60 minutes. After 120 min rewarming period pathological changes of lumbar segmental （L2） spinal cord were observed. The concentration of energy - related metabolites and amino acid were examined. RESULTS During the arrest period a decrease of pyruvat level and an increase of the ratio of lactate - pyruvate were observed respectively. Glucose, lactate acid, pyruvat and glycerine concentration was increased significant during reperfusion. Glu and gama -aminobutyric acid（GABA） increased in CPB 30 minute. In the sample taken during the 120 minutes after reperfusion, there were increase in Asp and Tau. The pathological injury of the spinal cord was slightly. CONCLUSION Deep hypothermic reduces the spinal cord energetic metabolism during circulatory arrest. The increase of Glu and GABA in CPB period, Asp, Gly and Tau during reperfusion period may lead to the injury of spinal cord.