The mechanisms of increased insulin sensitivity in rat skeletal muscle following low-intensity prolonged exercise

运动增加骨骼肌摄取葡萄糖的胰岛素敏感性。然而，运动的组成（持续时间，强度，体积），决定运动后胰岛素敏感性是不确定的。本实验研究了低强度长时间游泳（LIS; 3 h）和高强度短时游泳（HIS; 160 sec）对大鼠快收缩滑车上肌胰岛素敏感性的影响。与静息对照相比，LIS和HIS均能增加肌肉胰岛素敏感性，但在乳酸阈附近强度（50%VO2max）的LIS比远高于乳酸阈的强度（140%VO2max）的HIS更能增加肌肉胰岛素敏感性。本研究进一步采用跑台运动法，以6 m/min和9 m/min的速度对大鼠进行90- 360 min的跑台运动，并测定运动后胰岛素的变化 ...更多信息 慢收缩比目鱼肌的敏感性。这些踏车行走的强度小于乳酸阈值。以9 m/min而不是6 m/min的速度在跑步机上行走可增强大鼠慢收缩比目鱼肌的胰岛素敏感性。因此，强度低于乳酸阈的极低强度运动可以增加肌肉胰岛素敏感性。然而，这是可能的，最低运动强度是需要增加运动后胰岛素敏感性在大鼠慢缩比目鱼肌。在我们目前的研究中，LIS，而不是HIS增加Sirt 1 mRNA在大鼠上滑车肌的表达。因此，骨骼肌中的Sirt 1基因表达可能随着运动量的增加而增加。由于已知Sirt 1调节肌肉胰岛素信号传导，所以LIS诱导的肌肉胰岛素敏感性增强可能是由Sirt 1基因表达增加介导的。此外，我们发现Sirt 1的基因表达增加发生在运动过程中招募的骨骼肌中。因此，运动诱导的Sirt 1基因表达增加主要是由于肌肉收缩活动。少

Exercise increases insulin sensitivity of glucose uptake in skeletal muscles. However, the constituent (duration, intensity, volume) of exercise which determines post-exercise insulin sensitivity is uncertain. The mechanism(s) of exercise-induced increase in muscle insulin sensitivity is also not clear.We examined the effects of low-intensity prolonged swimming (LIS; 3h) or high-intensity short-term swimming (HIS; 160 sec) on rat fast-twitch epitrochlearis muscle. Although both LIS and HIS increased muscle insulin sensitivity as compared with resting control, LIS which intensity (50% VO2max) is around lactate threshold increased muscle insulin sensitivity to higher level than HIS which intensity (140% VO2max) is far above lactate threshold. Thus, it is suggested that total volume of exercise is important determinant of post-exercise insulin sensitivity.Furthermore, in our present study, we exercised rats for 90-360min by treadmill at 6m/min or 9m/min and examined post-exercise insulin … More sensitivity in slow-twitch soleus muscle. The intensity of these treadmill walking is less than lactate threshold. Treadmill walking at 9m/min, but not at 6m/min, enhanced insulin sensitivity in rat slow-twitch soleus muscle. Thus, very low-intensity exercise which intensity is less than lactate threshold can increase muscle insulin sensitivity. However, it is probable that minimum exercise intensity is required for increasing post-exercise insulin sensitivity in rat slow-twitch soleus muscle.In our present study, LIS but not HIS increased Sirt1 mRNA expression in rat epitrochlearis muscle. Therefore, it is likely that Sirt1 gene expression in skeletal muscle increases in accordance with the increase in exercise volume. Since Sirt1 is known to regulate muscle insulin signaling, it is possible that LIS-induced enhancement of muscle insulin sensitivity is mediated by increased Sirt1 gene expression. Furthermore, we found that increased gene expression of Sirt1 occurred in skeletal muscles recruited during exercise. Thus, exercise-induced increase in Sirt1 gene expression is mainly due to muscle contractile activity. Less