Insulin can alleviate degradation of skeletal muscle protein by inhibiting ubiquitin - proteasome system in septic rats

陈启仪¹ 虞文魁¹ 李宁¹ 李维勤¹ 朱维铭¹ 高涛¹ 唐少秋¹ 张娟娟¹ 黎介寿¹
南京军区南京总医院外科ICU

we had similarly been confirmed that mRNA and protein levels of ubiquitin-proteasome system were up-regulated and molecular mark of skeletal muscle proteolytic(tyrosine and 3-methylhistidine) were also increased simultaneously in muscle skeletal of septic rats. Then the septic rats were infused insulin at the constant rate of 2.4 mU.kg^-1.min^-1 for 8 hours. Express of mRNA, proteins concentration of ubiquitin-proteasome system and molecular mark of skeletal muscle proteolytic were affected mildly. When the infusion dose of insulin increased to 4.8 mU.kg^-1.min^-1, however, we were surprised to find that ubiquitin and E2-14KDa and C2 subunit mRNA all were down-regulated sharply. At the same time, the level of ubiquitined proteins, E2-14KDa and C2 subunit proteins level were significantly reduced. Eventually tyrosine and 3-methylhistidine decreased significantly. We concluded that ubiquitin-proteasome system had played an important role in skeletal hyper-catabolism for septic rats.