蛋白酶体-C2亚基基因在烫伤脓毒症大鼠心肌内的表达及意义

Gene expression of C2 subunit of proteasome in cardiac muscle in burned rats with sepsis

目的 探讨烧伤脓毒症时动物心肌内蛋白酶体核心亚基C2亚基m RNA表达及蛋白降解的变化及意义。方法 雄性Wistar大鼠4 5只,随机分为烫伤组、脓毒症组及对照组。烫伤组大鼠使用沸水致背部30 %总体表面积 度烫伤;脓毒症组大鼠用同样方法烫伤后,立即腹腔注射内毒素(6 m g/ kg)制成烫伤脓毒症大鼠模型。通过高效液相荧光法检测心肌内三甲基组氨酸(3MH)的含量,用核糖核酸印迹杂交(Northern杂交)检测心肌内蛋白酶体C2亚基m RNA表达的变化。结果 脓毒症大鼠烫伤后2 h和6 h,单位心肌内3MH含量较对照组和烫伤组均显著升高(P均<0 .0 1) ;烫伤组大鼠伤后2 h与对照组比较差异无显著性(P>0 .0 5 ) ,而伤后6 h较对照组显著升高(P<0 .0 1)。脓毒症大鼠伤后2 h和6 h心肌内蛋白酶体C2亚基m RNA表达较对照组和烫伤组均显著升高(P均<0 .0 1) ,烫伤组大鼠伤后2 h和6 h较对照组也均显著升高(P均<0 .0 1)。结论 严重烫伤特别是合并内毒素攻击后,早期动物心肌细胞内泛素蛋白酶体途径活性呈持续增强现象,蛋白降解率显著增加。这可能是烧伤脓毒症时心功能异常的蛋白代谢机制。

Objective To study the gene expression of C2 subunit of proteasome and proteolysis in cardiac muscle in burned animals with sepsis. Methods Male Wistar rats were randomly divided into burn group, burn sepsis group and control group. The extent of burn injury was 30% total body surface area ( TBSA ) Ⅲ degree burn, and the model of burn sepsis was replicated by administration of endotoxin ( 6 mg/kg ) into the peritoneal cavity immediately after burn injury. The contents of 3methylhistidine (3MH) in cardiac muscle were determined with high performance liquid chromatography. The expression of C2 subunit mRNA in the cardiac muscle was assessed with Northern blot analysis. Results The contents of 3MH in cardiac muscle of burned rats with sepsis increased significantly at 2 hours and 6 hours , as compared with burned rats and normal control (all P <0.01). There was no marked difference of contents of 3MH in cardiac muscle between burned rats at 2 hours and control group, however, the contents of 3MH in cardiac muscle of burned rats at 6 hours increased significantly compared with control group. The gene expression of C2 subunit in cardiac muscle of burned rats with sepsis increased significantly at 2 hours and 6 hours compared with burned rats and normal control (all P <0.01). There were significant differences in the intensity of gene expression of C2 subunit in cardiac muscle between burned rats at 2 hours and 6 hours and normal control (all P <0.01). Conclusion The data suggest that the activity of ubiquitin system, one of important protein degradation pathways, and the proteolysis in cardiac muscle is continuously enhanced after burn injury, especially when sepsis setin, probably contributes to abnormal protein metabolism with malfunction of the heart during burn sepsis.