TOTAL AND MYOFIBRILLAR PROTEIN BREAKDOWN IN DIFFERENT TYPES OF RAT SKELETAL-MUSCLE - EFFECTS OF SEPSIS AND REGULATION BY INSULIN
TOTAL AND MYOFIBRILLAR PROTEIN BREAKDOWN IN DIFFERENT TYPES OF RAT SKELETAL-MUSCLE - EFFECTS OF SEPSIS AND REGULATION BY INSULIN
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DOI：
10.1016/0026-0495(89)90100-5
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发表时间：
1989-07-01
影响因子：
9.8
通讯作者：
FISCHER, JE
中科院分区：
文献类型：
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作者：
HASSELGREN, PO;JAMES, JH;FISCHER, JE
蛋白分解在脓毒症中增加，但目前尚不清楚肌原纤维和非肌原纤维蛋白是否以相同的方式分解，或对与非脓毒症肌肉相同的调节力做出反应。因此，本研究测定了脓毒症对培养的大鼠趾长伸肌(EDL)和比目鱼肌(SOL)总蛋白和肌原纤维蛋白降解的影响，并研究了不同浓度的胰岛素(10~105u.U/mL)对体外培养的EDL肌肉蛋白质降解的反应。采用盲肠结扎穿孔(CLP)法制备大鼠脓毒症模型。对照组动物为假手术。CLP或假手术后16h，在含葡萄糖(10 mmoL/L)和放线菌亚胺(0.5 mmoL/L)的含氧Krebs-Henseleit碳酸氢盐缓冲液中孵育完整的内侧前交叉韧带和SOL肌2小时，分别在酪氨酸和3-甲基组氨酸(3-MH)孵育介质中测定总蛋白和肌原纤维蛋白的降解。用高效液相色谱法测定酪氨酸和3-MH的含量。在孵育2小时期间，对照肌肉和败血症肌肉中的酪氨酸和3-MH的组织水平保持稳定。脓毒症时EDL和SOL肌肉的酪氨酸释放率分别增加58%(P<；.001)和15%(NS)。3-MH的相应数字为103%(P<；.001)和21%(NS)。在对照肌肉和败血症肌肉中，浓度分别为103u.U/m L和104.u/m L的胰岛素可减少酪氨酸的释放。对照组大鼠EDL肌肉中3-MH的释放不受任何浓度的胰岛素影响，而败血症大鼠肌肉中3-MH的释放在103~105u.U/mL浓度范围内被胰岛素抑制11%~25%。这些结果表明，肌原纤维蛋白比非肌原纤维蛋白对脓毒症的影响更敏感，白色肌肉中的蛋白质分解比红色肌肉中的蛋白质分解更容易发生脓毒症。结果还表明，肌原纤维和总蛋白独立地受胰岛素调节，在脓毒症期间对胰岛素的反应发生改变。
Proteolysis is increase in sepsis, but it is not known whether myofibrillar and non-myofibrillar proteins are broken down in the same fashion, or respond to the same regulatory force as in non-septic muscle. In this study, therefore, the effect of sepsis on total and myofibrillar protein breakdown in incubated rat extensor digitorum longus (EDL) and soleus (SOL) muscles was determined, and the response in vitro to different concentrations of insulin (10 to 105 .mu.U/mL) of protein degradation was studied in incubated EDL muscles from control and septic rats. Sepsis was induced in rats weighing 40 to 60 g by cecal ligation and puncture (CLP). Control animals were sham operated. Sixteen hours after CLP or sham operation, intact EDL and SOL muscles were incubated for two hours in oxygenated Krebs-Henseleit bicarbonate buffer containing glucose (10 mmol/L) and cycloheximide (0.5 mmol/L), and total and myofibrillar protein breakdown was assessed from release into incubation medium of tyrosine and 3-methylhistidine (3-MH), respectively. Tyrosine and 3-MH were determined fluorometrically by high performance liquid chromatography (HPLC). Tissue levels of tyrosine and 3-MH remained stable both in control and septic muscles during incubation for two hours. The rate of tyrosine release was increased during sepsis by 58% (P < .001) and 15% (NS) in EDL and SOL muscle, respectively. The corresponding figures for 3-MH were 103% (P < .001) and 21% (NS). Tyrosine release was reduced by insulin at a concentration of 103 .mu.U/mL in control muscle and at a concentration of 104 .mu.U/mL in septic muscle. 3-MH release by incubated EDL muscle from control rats was not affected by insulin at any concentration tested, while in septic muscle 3-MH release was reduced by 11% to 25% by insulin at concentrations ranging from 103 to 105 .mu.U/mL. The present results suggest that myofibrillar protein are more sensitive than non-myofibrillar proteins to the effects of sepsis, and that protein breakdown in white muscle is more susceptible to sepsis than proteolysis in red muscle. The results also indicate that myofibrillar and total proteins are regulated independently by insulin and that the response to insulin is altered during sepsis.