大鼠腓肠肌的肌纤维型组成及分布

Composition and distribution of muscle fiber types in the rat gastrocnemius muscle

目的:探讨SD大鼠腓肠肌的肌纤维型组成和分布,借以了解该肌功能。方法:采用Guth-Samaha肌球蛋白ATP酶组织化学染色法并稍做改良,对成年SD大鼠腓肠肌冰冻切片进行肌纤维分型研究。结果:SD大鼠腓肠肌经肌球蛋白ATP酶组织化学染色后可明确分出2型肌纤维,即明亮色白的Ⅰ型纤维(慢缩纤维)和幽暗深褐的Ⅱ型纤维(快缩纤维),并且,2种纤维在肌内呈棋盘样均匀分布;图像分析仪计数Ⅱ型纤维比例达(72.2±6.8)%,而Ⅰ纤维仅占(27.8±2.4)%,前者占绝对优势(P<0.01)。结论:SD大鼠腓肠肌以Ⅱ型纤维为主,属于力量兼速度型肌。

Objective：To study the composition and distribution of two muscle fiber types in SD rat gastrocnemius muscle in order to learn its function. Methods：Gastrocnemius muscles of both sides of hind limbs were collected from 10 adult SD rats. 8μm-thick cryostat sections were transected and then stained with the method of myosin-ATPase following a proeesure modified partially from one that Guth ＆ Samaha reported before. Results：Gastrocnemius muscle from SD rats can be clearly identified with two different fiber types which are type Ⅰ （slow twitch fiber）and type Ⅱ （fast twitch fiber） by the myosin-ATPase staining method. Fibers of type I are stained white while fibers of type Ⅱ are stained brown. The distribution pattern of two types of muscle fibers in gastrocnemius muscles is uniform and chessboard-like. The proportion of type Ⅱ muscle fibers contained in the muscle is（72.2±6.8）%,much higher than that of type Ⅰ fibers which is （27.8 ±2.4）%（P〈0.01）. Conclusion： Fast-twitch glycolytic （FG） fibers are dominant in SD rat gastrocnemius muscles,which implies that gastrocnemius muscles participate more in fast stepping movement.