大鼠胸深肌肌纤维型的组成及分布

Composition and distribution of fiber types in the rat deep pectoral muscle

目的探讨SD大鼠胸深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大鼠胸深肌冰冻切片进行肌纤维分型研究。结果大鼠胸深肌经肌球蛋白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,两种纤维在肌内呈棋盘样均匀分布;图像分析仪下计数Ⅱ型纤维达到65%±6%,而Ⅰ纤维仅占35%±5%,前者明显高于后者(P<0.01)。结论大鼠胸深肌以Ⅱ型纤维为主,属于力量和速度型肌。

Objective To investigate the fiber types composition and distribution of SD rat deep pectoral muscle and evaluate its function. Methods Deep pectoral muscles of both sides were collected from 10 adult SD rats. 8 μm-thick cryostat sections were transected and then stained with the myosin-ATPase method following a procedure modified partially from-the one that Guth ＆ Samaha reported before. Results Two different fiber types （type Ⅰ ： slow twitch fiber, type Ⅱ ： fast twitch fiber） of deep pectoral muscles from SD rats can be clearly identified. Fibers of type Ⅰ are stained white while fibers of type Ⅱ were stained brown. The distribution pattem of the two types of muscle fibers in the muscle was uniform and chessboard-like. The proportion of type Ⅱ muscle fibers contained in the muscle was 65%＋6%, much higher than that of type Ⅰ fibers which was （35%±5%, P〈0.01 ）. Conclusion SD rat deep pectoral muscle mainly contained of type Ⅱ muscle fiber, which imply that the muscle participate more in fast stepping movement.