Le Marchand-Brustel Y, Monier S, Freychet P
Reprod Nutr Dev (1980). 1983;23(2 B):413-9.
The uptake of alpha-aminoisobutyric acid (AIB) and protein synthesis were studied in soleus muscles isolated from lean and goldthioglucose-obese mice (GTG-obese mice) in both basal and insulin-stimulated conditions. Insulin stimulated AIB influx by increasing the apparent Vmax of transport; this effect was partially dependent on new protein synthesis. In muscles of GTG-obese mice, the basal (i.e. non-insulin-stimulated) influx of AIB was decreased. Furthermore, the effect of insulin in obese mice was altered in two ways; the absolute value of the maximally insulin-stimulated AIB influx was lower than in the muscles of lean controls, and the dose response of insulin-stimulated AIB influx was shifted to the right (half-maximally effective concentration: EC50 approximately equal to 1.7 nM) compared to that observed in the muscles of lean animals (EC50 approximately equal to 0.7 nM). On the contrary, protein synthesis was similar in control and GTG-obese mice in both basal and insulin-stimulated conditions. It is concluded that in the muscles of obese mice a) amino acid transport per se is altered, b) the sensitivity of this process to the stimulatory effect of insulin is markedly diminished and c) protein synthesis is unchanged.
在基础状态以及胰岛素刺激状态下，对从正常小鼠和金硫葡萄糖诱导的肥胖小鼠（GTG肥胖小鼠）分离出的比目鱼肌中α-氨基异丁酸（AIB）的摄取和蛋白质合成进行了研究。胰岛素通过增加转运的表观最大速率（Vmax）来刺激AIB内流；这种作用部分依赖于新的蛋白质合成。在GTG肥胖小鼠的肌肉中，AIB的基础（即非胰岛素刺激）内流减少。此外，肥胖小鼠中胰岛素的作用在两个方面发生了改变；最大胰岛素刺激的AIB内流的绝对值低于正常对照小鼠的肌肉，并且与正常动物肌肉中观察到的情况相比，胰岛素刺激的AIB内流的剂量反应向右移动（半数最大效应浓度：EC50约为1.7 nM）（正常动物肌肉中EC50约为0.7 nM）。相反，在基础状态和胰岛素刺激状态下，正常小鼠和GTG肥胖小鼠的蛋白质合成相似。得出的结论是，在肥胖小鼠的肌肉中，a）氨基酸转运本身发生了改变，b）该过程对胰岛素刺激作用的敏感性明显降低，c）蛋白质合成未发生变化。
