应用稳定同位素技术研究烧伤大鼠蛋白质代谢变化

The study of protein metabolic rate of the severely burned SD rats by stable isotope technique

目的本研究旨在应用稳定同位素技术,在建立稳定的严重烫伤大鼠模型的基础上,量化严重烫伤大鼠伤后总体蛋白代谢率。方法采用严重烫伤动物模型,雄性SD大鼠20只,随机分为两组:假伤组(n=10)和烫伤组(n=10),伤后4d给予示踪氨基酸(2H标记的亮氨酸),给予示踪氨基酸后0.5h,由腹腔动脉取血液标本。将血清样本沉淀取蛋白,分别进行亮氨酸衍生、酮异己酸(KIC)衍生、结合氨基酸处理,经过GC-MC检测,计算比较两组大鼠血浆游离氨基酸2H丰度、亮氨酸更新速率、整体蛋白质分解速率、整体蛋白合成速率。结果 (1)烫伤组血浆游离氨基酸2H丰度明显高于假伤组,烫伤组较假伤组增加了48.24%,差异有统计学意义(P<0.05)。(2)烫伤组亮氨酸更新速率为(236.2±13.1)μmol·kg-1·h-1,假伤组为(132.2±6.5)μmol·kg-1·h-1,烫伤组较假伤组增加了78.6%,差异有统计学意义(P<0.05)。(3)烫伤组大鼠整体蛋白分解速率为(9.1±1.6)g·kg-1·d-1,较假伤组(5.1±0.5)g·kg-1·d-1有明显增加,前者较后者增高78.4%(P<0.05)。(4)烫伤组大鼠整体蛋白合成速率为(5.1±1.8)g·kg-1·d-1,假伤组(4.8±1.1)g·kg-1·d-1,差异无统计学意义(P>0.05)。(5)烫伤大鼠为负氮平衡状态[(-4.0±1.0)g·kg-1·d-1]。结论严重烫伤会导致大鼠蛋白质分解速率增加,处于负氮平衡状态。

Objective To quantify the overall protein metabolic rate of the severely burned SD rats on the basis of a stable model of burned rats being established by stable isotopic technique. Methods Measurement of overall protein metabolic rate of burned SD rats：The above burned animal model was further used. Twenty male SD rats were randomly divided into 2 groups ： （ 1 ） sham scald group （ n = 10）, （2） scald group （ n = 10）. All the rats were injected with the tracer amino acid solution,2H-leucine,4 d post injury. Blood samples were taken from celiac axis 0. 5 h after the injection. Thereafter, serum were treated with leucin derivation, KIC derivation, amino acid combination after protein precipitation. Then, the treated serum were subjected to GC-MC detection. The plasma free-2H amino acid abundance, leucine updating rate, protein degradation rate and protein incorporation rate of the two groups of rats were calculated and analyzed. Results （ 1 ） The plasma free-2 H amino acid abundance in the scald group was 48.24% higher than that in the sham scald group. The difference was remarkable （ P 〈 0. 05 ）. （2） The leucine updating rate in scald group was（236. 2 ± 13.1 ） txmol ~ kg-＇ ~ h-l ,while that of the sham scald group was （ 132. 2 ±6. 5） μmol·kg-1· h-1. The former was 78.6% higher than the latter and the difference had statistical significance（P 〈0. 05）. （3）The overall protein degradation rate in the scald group was（9. 1± 1.6）g ·kg-1·d-1 much higher than that in the sham scald group, （5.1 ~ 0. 5 ） g ·kg-1·d-1. The former was 78.4% more than the latter（P 〈 0. 05）. （4）As for the protein incorporation rate, there was no statistical difference（ P = 0. 067 ）between （ 5.1 ± 1.8 ） g ·kg-1·d-1 of the scald group and （4. 8 ± 1.1 ） g ·kg-1·d-1 of the sham scald group. （ 5 ） Negative nitrogen balance was found in the scald group [ （ -4. 0 ± 1.0 ）g ·kg-1·d-1]. Conclusions The protein degradation rate of rats increases evidently after burned, this is a negative nitrogen balance.