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脊椎动物平滑肌的显著特点,是尽管其肌球蛋白含量较低,却能产生与骨骼肌相当的张力,并能缩短到远小于其静止长度的一半。同时,因为平滑肌是由小而单核的细胞组成,故细胞间的连接在兴奋和力的传递中起了关键性作用。一般认为骨骼肌的肌丝滑动学说也适用于平滑肌。但是平滑肌的肌球蛋白丝较少,肌球蛋白丝与肌动蛋白丝的比率从1∶8(鸡砂囊)到1∶15(免血管平滑肌)不等。肌动蛋白丝围绕肌球蛋白丝排列成玫瑰花结状或环状,或集聚成束,并可组成分枝的网。肌动蛋白丝在胞质内与
The striking characteristic of vertebrate smooth muscle is that it produces comparable tension to skeletal muscle despite its low myosin content and can be shortened to much less than half its resting length. In the meantime, since the smooth muscle is composed of small, mononuclear cells, the connection between the cells plays a crucial role in the excitement and force transmission. Is generally believed that skeletal muscle slippage theory also applies to smooth muscle. However, the myosin filaments of smooth muscle were less, and the ratio of myosin filaments to actin filaments ranged from 1: 8 (chicken gizzard) to 1:15 (free of vascular smooth muscle). Actin filaments around the myosin filaments arranged in rosettes or rings, or gathered into bundles, and can form a branched network. Actin filaments in the cytoplasm