脓毒症大鼠血浆游离氨基酸浓度的变化

Changes in plasma free amino acid concentrations in rats during sepsis

目的 探讨脓毒症早期大鼠血浆游离氨基酸含量的变化与骨骼肌蛋白降解间的关系。 方法 以腹腔注射内毒素建立大鼠脓毒症模型 ,将动物随机分为正常对照组和内毒素攻击后 2、6、12、2 4h共 5组 ,每组 8只动物。用氨基酸自动分析仪的生理体液柱测定各组大鼠血浆游离氨基酸含量 ;用全自动生化分析仪测定血浆谷丙转氨酶 (ALT)和谷草转氨酶 (AST)浓度 ;用放射免疫分析 (RIA)法测定血浆皮质醇含量 ;用酶联免疫吸附试验 (ELISA)测定血浆TNF α和IL 6含量。 结果 内毒素攻击后各时相点大鼠血浆总氨基酸含量在正常范围内波动 ;支链氨基酸 (BCAA)在 2、6、12h降低 ,2 4h则出现显著升高 ,亮氨酸、异亮氨酸无显著性变化 ,缬氨酸早期明显降低 ,后期则上升 ;芳香族氨基酸(AAA)在各时相点不同程度升高 ,2h和 6h显著升高 ,酪氨酸 12h降低 ,苯丙氨酸在各时相点均显著升高 ;苯丙氨酸 /酪氨酸 (Phe/Tyr)比值内毒素攻击后各时相点均出现显著增加 ;BCAA/AAA比值在 2h和 6h较正常显著降低 ;苏氨酸、谷氨酸、鸟氨酸、3 甲基组氨酸 (3 MH)、组氨酸、丙氨酸早期升高或大多数时相点显著升高 ,赖氨酸、肌氨酸、胱氨酸和磷酸丝氨酸在内毒素攻击后无显著性变化 ,其它氨基酸均见不同程度的降低或显著降低。血浆ALT。

Objective To explore the relationship between plasma free amino acid concentrations and skeletal muscle proteolysis in rats during sepsis. Methods An animal model of sepsis in rats was established by administering endotoxin into the peritoneal cavity. The plasma concentrations of free amino acid, ALT, AST, cortisol, TNF α and IL 6 were determined. The rats were randomly divided into normal control, 2, 6, 12 and 24 h groups after administration of endotoxin(8 rats for each group). Results The total plasma free amino acids concentrations fluctuate within normal range within 24 h after administration of endotoxin. A marked decrease in BCAA(branch chainamino acid)was observed at 2, 6 and 12 h after administration of endotoxin,but aromatic amino acids(AAA) increased in varying degrees. BCAA/AAA was lower at 2 h and 6 h as compared with that of the normal control, while Phe/Tyr increased obviously at every time point. Lys, Sar, Cys and P Ser showed no significant changes within 24 h after the administration of endotoxin. Thr, Glu, Orn, His, 3 MH and Ala increased during sepsis,and other amino acids more or less decreased. Plasma concentrations of ALT, AST, cortisol, TNF α and IL 6 obviously increased within 24 h after the administration of endotoxin( P <0 01). Cortisol peaked at 6 h and IL 6 peaked at 12 h,while TNF α at 2 h. Conclusion The results suggested that metabolic disorder of plasma free amino acids during sepsis is due to enhancement of skeletal muscle proteolysis and liver overloading.