Curfman G D, O'Hara D S, Hopkins B E, Smith T W
Circ Res. 1980 Apr;46(4):581-9. doi: 10.1161/01.res.46.4.581.
To study the effects of leucine, glucose, and insulin on myocardial protein degradation in fed and fasted nutritional states, we developed and validated a sensitive method for measuring rates of total protein degradation in rat isolated left atrial preparations. Fasting resulted in a progressive decrease in myocardial protein breakdown to 71% of control over a 24-hour period, with no further reduction in degradation rate between 24 and 72 hours of fasting. Insulin (100 mU/ml) suppressed atrial protein degradation by 38% in fed animals (P less than 0.001) and by 51% in fasted animals (P less than 0.001). Glucose alone had no effect on protein degradation in either nutritional state. At 5 times normal plasma levels, leucine suppressed protein breakdown by 21% in fed and by 15% in fasted animals. The decrease in degradation induced by fasting and the absence of an effect of glucose are in contrast to the behavior reported for skeletal muscle.
为研究亮氨酸、葡萄糖和胰岛素在进食及禁食营养状态下对心肌蛋白降解的影响，我们开发并验证了一种灵敏的方法，用于测量大鼠离体左心房标本中总蛋白降解速率。禁食导致心肌蛋白分解在24小时内逐渐下降至对照组的71%，禁食24至72小时期间降解速率未进一步降低。胰岛素（100 mU/ml）在进食动物中使心房蛋白降解减少38%（P<0.001），在禁食动物中减少51%（P<0.001）。单独的葡萄糖在两种营养状态下均对蛋白降解无影响。在血浆水平为正常5倍时，亮氨酸在进食动物中使蛋白分解减少21%，在禁食动物中减少15%。禁食引起的降解减少以及葡萄糖无作用，这与骨骼肌的报道情况相反。
