Fung Y C, Liu S Q
Department of Bioengineering, University of California, San Diego, La Jolla 92093-0412.
Proc Natl Acad Sci U S A. 1995 Mar 14;92(6):2169-73. doi: 10.1073/pnas.92.6.2169.
The structure and materials of the blood vessel wall are layered. This article presents the principle of a method to determine the mechanical properties of the different layers in vivo. In vivo measurement begets in vivo data and avoids pitfalls of in vitro tests of dissected specimens. With the proposed method, we can measure vessels of diameters 100 microns and up and obtain data on vascular smooth muscles and adventitia. To derive the full constitutive equations, one must first determine the zero-stress state, obtain the morphometric data on the thicknesses of the layers, and make mechanical measurements in the neighborhood of the zero-stress state. Then eight small perturbation experiments are done on earth blood vessel in vivo to determine eight incremental elastic moduli of the two layers of the blood vessel wall. The calculation requires the morphometric data and the location of the neutral axis. The experiments are simple, the interpretation is definitive, but the analysis is somewhat sophisticated. The method will yield results that are needed to assess the stress and strain in the tissues of the blood vessel. The subject is important because blood vessels remodel themselves significantly and rapidly when their stress and strain deviate from their homeostatic values, and because cell proliferation, differentiation, adhesion, contraction, and locomotion depend on stress and strain in the tissue.
血管壁的结构和材料是分层的。本文介绍了一种在体内确定不同层力学性能的方法原理。体内测量可获得体内数据，并避免了解剖标本体外测试的缺陷。采用所提出的方法，我们可以测量直径为100微米及以上的血管，并获得血管平滑肌和外膜的数据。为了推导完整的本构方程，首先必须确定零应力状态，获取各层厚度的形态测量数据，并在零应力状态附近进行力学测量。然后在活体血管上进行八个小扰动实验，以确定血管壁两层的八个增量弹性模量。计算需要形态测量数据和中性轴的位置。实验简单，解释明确，但分析略显复杂。该方法将得出评估血管组织应力和应变所需的结果。这个主题很重要，因为当血管的应力和应变偏离其稳态值时，血管会显著且迅速地自我重塑，还因为细胞增殖、分化、黏附、收缩和运动取决于组织中的应力和应变。
