Ohayon J, Chadwick R S
Division of Research Services, National Institutes of Health, Bethesda, Maryland 20892.
Biophys J. 1988 Dec;54(6):1077-88. doi: 10.1016/S0006-3495(88)83044-3.
The microstructure of the collagen sheath or weave surrounding a myocyte and the collagen struts interconnecting neighboring myocytes is incorporated into a fluid-fiber-collagen continuum description of the myocardium. The sheaths contribute to anisotropic elasticity, whereas the struts contribute to an isotropic component. Elastic moduli of the composite myocyte-sheath complex and the strut matrix are estimated from existing passive biaxial loading data from sheets of canine myocardium. The contribution of the sheath to the elasticity of the myocyte-sheath complex is critically dependent on the helical pitch angle. Calculations for a cylindrical model of the left ventricle using both a fluid-fiber and fluid-fiber-collagen stress tensor show that the collagen strut matrix tends to limit muscle fiber lengthening; increase myocardial tissue pressure during systole, with endocardial tissue pressure exceeding left ventricular pressure; decrease tissue pressure during diastole, and thus facilitate myocardial blood flow; and aid filling during ventricular relaxation by providing a suction effect that relies on a release of stored elastic energy from the previous contraction. Calculations show that this energy is stored mostly in the collagen struts.
围绕心肌细胞的胶原鞘或编织结构以及连接相邻心肌细胞的胶原支柱，被纳入心肌的流体 - 纤维 - 胶原连续体描述中。鞘有助于各向异性弹性，而支柱有助于各向同性成分。根据犬心肌薄片现有的被动双轴加载数据，估算复合心肌细胞 - 鞘复合体和支柱基质的弹性模量。鞘对心肌细胞 - 鞘复合体弹性的贡献严重依赖于螺旋螺距角。使用流体 - 纤维和流体 - 纤维 - 胶原应力张量对左心室圆柱模型进行的计算表明，胶原支柱基质倾向于限制肌纤维延长；在收缩期增加心肌组织压力，心内膜组织压力超过左心室压力；在舒张期降低组织压力，从而促进心肌血流；并通过提供一种依赖于从前一次收缩中释放储存的弹性能量的抽吸效应，在心室舒张期辅助充盈。计算表明，这种能量主要储存在胶原支柱中。
