Regulation of myofibrillar protein degradation in rat skeletal muscle during brief and prolonged starvation.
Regulation of myofibrillar protein degradation in rat skeletal muscle during brief and prolonged starvation.
复制标题
短暂和长期饥饿期间大鼠骨骼肌肌原纤维蛋白降解的调节。
DOI：
10.1016/0026-0495(86)90025-9
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发表时间：
1986
期刊：
影响因子：
--
通讯作者：
Goodman,MN
中科院分区：
文献类型：
--
作者：
Lowell,BB;Ruderman,NB;Goodman,MN
肌原纤维蛋白分解在短期和长期饥饿的灌流大鼠骨骼肌从8周龄的脂肪喂养的大鼠，保存骨骼肌蛋白在饥饿和生存12至15天，年龄匹配的饲料喂养的大鼠，不保存蛋白质和生存只有5至6天。放线菌酮抑制蛋白质合成后，肌原纤维蛋白水解进行了评估，通过测量3-甲基组氨酸从灌注大鼠后躯的释放，同时测量总蛋白质分解进行了评估，通过测量酪氨酸释放。肌原纤维蛋白水解进展通过三个不同的阶段，在饥饿：早期阶段发生在24小时内，蛋白水解增加，在所有大鼠，中间阶段，这需要三到五天的发展，在此期间，蛋白水解减少，只存在于脂肪喂养的大鼠，和后期阶段，蛋白水解再次增加。总蛋白分解（即酪氨酸释放）在I期变化不大，在II期减少，在III期增加。3-甲基组氨酸的释放从灌注后躯反映了肌肉和尿液的完整大鼠的变化，这表明与灌注后躯获得的数据反映了在体内的情况。胰岛素，氨基酸，高浓度的葡萄糖，吲哚地辛，肾上腺素，以及肾上腺切除术未能减弱3-甲基组氨酸释放的增加，从灌注的后腿在短暂的和晚期饥饿。游离脂肪酸和酮体在体外也没有影响。禁食4小时后再喂饲可降低肌原纤维蛋白水解。这些数据表明，肌原纤维和非肌原纤维蛋白的分解可以对饥饿做出不同的反应，甚至可能在禁食的不同阶段做出反应。先前已知的一般肌肉蛋白水解调节剂不能急性减弱肌原纤维蛋白水解，这表明如果它们发挥作用，则需要更长时间暴露于肌肉。此外，这些数据表明，肌原纤维蛋白水解的显着变化可能发生在总蛋白质分解没有揭示的情况下。未来的研究试图描绘肌肉中蛋白水解的调节机制，必须考虑到这一点。
Myofibrillar protein breakdown during brief and prolonged starvation was assessed in perfused rat skeletal muscle from 8-week-old fat-fed rats that conserve skeletal muscle protein during starvation and survive for 12 to 15 days and age-matched chow-fed rats that do not conserve protein and survive only five to six days. Following the inhibition of protein synthesis with cycloheximide, myofibrillar proteolysis was assessed by measuring the release of 3-methylhistidine from the perfused rat hindquarter while simultaneous measurement of total protein breakdown was assessed by measuring tyrosine release. Myofibrillar proteolysis progressed through three distinct phases during starvation: an early phase occurring within 24 hours in which proteolysis increased in all rats, a middle phase, which took three to five days to develop and during which proteolysis decreased and was present only in fat-fed rats, and a late phase in which proteolysis again increased. Total protein breakdown (ie, tyrosine release) changed little in phase I, decreased in phase II, and increased in phase III. The release of 3-methylhistidine from the perfused hindquarter reflected changes in muscle and urine of intact rats suggesting that data obtained with the perfused hindquarter reflected the in vivo situation. Insulin, amino acids, high concentrations of glucose, indodethacin, or epinephrine as well as adrenalectomy failed to attenuate the increase in 3-methylhistidine release from the perfused hindquarter during brief and late starvation. Free fatty acids and ketone bodies were also without effect in vitro. Refeeding fasting rats for four hours decreased myofibrillar proteolysis. The data indicate that the breakdown of myofibrillar and nonmyofibrillar proteins can respond differently to starvation and may even do so at different stages of the fast. Previous known modulators of general muscle proteolysis were unable to attenuate myofibrillar proteolysis acutely, suggesting that if they play a role, a much longer exposure to muscle is necessary. Also, the data indicate that significant changes in myofibrillar proteolysis can occur in situations where total protein breakdown is not revealing. Future studies attempting to delineate regulatory mechanisms of proteolysis in muscle must be designed with this in mind.