Armstrong R B, Ianuzzo C D
Cell Tissue Res. 1977 Jul 11;181(2):255-66. doi: 10.1007/BF00219985.
Previous studies have demonstrated an apparent differential response of the fiber types in mixed skeletal muscles of rats to streptozotocin diabetes. The purpose of the present study was to examine the ability of the different fiber types to hypertrophy in muscles from diabetic rats, which should further clarify the apparent differential trophic influence of insulin on the fibers. One group of rats was injected with streptozotocin to induce diabetes. The gastrocnemius muscle was then removed from one hindlimb of rats of both the diabetic and a second, normal group, resulting in compensatory growth of ipsilateral plantaris muscle. Rats were sacrificed 60 days following the surgery. Experimental muscles in normal and diabetic rats enlarged 79% and 61% over control muscles, respectively. In normal hypertrophied muscles there was an 8% increase in relative cross-sectional area composed of slow-twitch fibers, whereas in diabetic rats the slow-twitch component increased 17%. The results indicate that slow-twitch fibers in diabetic rats were capable of responding to the chronic power overloaded condition, but that the fast-twitch fibers had a reduced capacity to undergo compensatory growth. These findings support our previous observations suggesting that insulin may exert a differential trophic effect upon the muscle fiber types.
先前的研究表明，大鼠混合骨骼肌中的纤维类型对链脲佐菌素诱导的糖尿病有明显的差异反应。本研究的目的是检测糖尿病大鼠肌肉中不同纤维类型的肥大能力，这将进一步阐明胰岛素对纤维明显的差异营养影响。一组大鼠注射链脲佐菌素以诱导糖尿病。然后从糖尿病组和另一正常组大鼠的一侧后肢取出腓肠肌，导致同侧跖肌的代偿性生长。术后60天处死大鼠。正常和糖尿病大鼠的实验肌肉分别比对照肌肉增大了79%和61%。在正常肥大肌肉中，由慢肌纤维组成的相对横截面积增加了8%，而在糖尿病大鼠中，慢肌成分增加了17%。结果表明，糖尿病大鼠的慢肌纤维能够对慢性力量过载状态做出反应，但快肌纤维进行代偿性生长的能力降低。这些发现支持了我们之前的观察结果，即胰岛素可能对肌肉纤维类型产生不同的营养作用。
