Whale M D, Grodzinsky A J, Johnson M
Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge 02139, USA.
Biorheology. 1996 Jan-Feb;33(1):17-44. doi: 10.1016/0006-355x(96)00003-0.
We measured the specific hydraulic conductivity (K) of the human and bovine aortic wall, two tissues for which K has not been previously reported in the literature, and examined the effects of aging (human) and development (bovine) on K. As part of the study, we also examined the effects of mounting the tissue in a flat or cylindrical configuration and the effects of perfusion pressure. With aging, in the human, we found a modest increase of K with age in a flat geometry; this trend was not apparent in a limited number of measurements in a cylindrical geometry. No significant dependence of K on developmental stage was found in the bovine aortic wall perfused in either a flat or cylindrical geometry. Our results indicate that aging and developmental changes of the aortic extracellular matrix have minimal effects on its hydrodynamic transport properties as measured. Mounting geometry for the aorta has been a concern reported in the literature since Yamartino et al. (1974) reported that K in the rabbit was 10-fold lower when measured in a flat geometry than in a cylindrical geometry. We found mounting geometry to make only a small difference in the calf and the cow, (Kflat approximately 2/3 of Kcylindrical), and in the human, we found K to be somewhat higher in the flat geometry than in the cylindrical geometry. Higher perfusion pressures decreased K of bovine tissue in the flat geometry, but pressure was not found to have a significant effect on K in the cylindrical geometry. An analytical model demonstrated that the anisotropic nature of the aortic wall allows it to be compressible (water-expressing) and yet remain at nearly constant tissue volume as the aorta is pressurized in a cylindrical geometry.
我们测量了人体和牛主动脉壁的比水力传导率（K），这是两种此前文献中未报道过K值的组织，并研究了衰老（人体）和发育（牛）对K的影响。作为该研究的一部分，我们还研究了将组织安装成扁平或圆柱形构型的影响以及灌注压力的影响。在人体中，随着衰老，我们发现扁平构型下K值随年龄适度增加；在圆柱形构型的有限测量中，这一趋势并不明显。在扁平或圆柱形构型下灌注的牛主动脉壁中，未发现K值对发育阶段有显著依赖性。我们的结果表明，主动脉细胞外基质的衰老和发育变化对其测量的流体动力学传输特性影响极小。自Yamartino等人（1974年）报道兔子在扁平构型下测量的K值比圆柱形构型下低10倍以来，主动脉的安装构型一直是文献中报道的一个问题。我们发现安装构型在小牛和母牛中造成的差异很小（K扁平约为K圆柱形的2/3），而在人体中，我们发现扁平构型下的K值略高于圆柱形构型。较高的灌注压力降低了扁平构型下牛组织的K值，但未发现压力对圆柱形构型下的K值有显著影响。一个分析模型表明，主动脉壁的各向异性性质使其具有可压缩性（排水），并且在主动脉在圆柱形构型中受压时仍能保持几乎恒定的组织体积。
