Ma Baoshun, Bates Jason H T
Department of Medicine, University of Vermont College of Medicine, Burlington, Vermont.
J Appl Physiol (1985). 2014 Mar 15;116(6):628-34. doi: 10.1152/japplphysiol.01180.2013. Epub 2014 Jan 30.
The forces of mechanical interdependence between the airways and the parenchyma in the lung are powerful modulators of airways responsiveness. Little is known, however, about the extent to which adjacent airways affect each other's ability to narrow due to distortional forces generated within the intervening parenchyma. We developed a two-dimensional computational model of two airways embedded in parenchyma. The parenchyma itself was modeled in three ways: 1) as a network of hexagonally arranged springs, 2) as a network of triangularly arranged springs, and 3) as an elastic continuum. In all cases, we determined how the narrowing of one airway was affected when the other airway was relaxed vs. when it narrowed to the same extent as the first airway. For the continuum and triangular network models, interactions between airways were negligible unless the airways lay within about two relaxed diameters of each other, but even at this distance the interactions were small. By contrast, the hexagonal spring network model predicted that airway-airway interactions mediated by the parenchyma can be substantial for any degree of airway separation at intermediate values of airway contraction forces. Evidence to date suggests that the parenchyma may be better represented by the continuum model, which suggests that the parenchyma does not mediate significant interactions between narrowing airways.
气道与肺实质之间的机械相互依存力是气道反应性的强大调节因素。然而，对于相邻气道因中间实质内产生的变形力而相互影响其狭窄能力的程度，人们知之甚少。我们建立了一个二维计算模型，模拟两个嵌入实质内的气道。实质本身通过三种方式建模：1）作为六边形排列弹簧的网络，2）作为三角形排列弹簧的网络，3）作为弹性连续体。在所有情况下，我们都确定了一个气道变窄时，另一个气道处于松弛状态与变窄到与第一个气道相同程度时，第一个气道变窄是如何受到影响的。对于连续体和三角形网络模型，气道之间的相互作用可以忽略不计，除非气道彼此之间的距离在大约两个松弛直径范围内，但即使在这个距离，相互作用也很小。相比之下，六边形弹簧网络模型预测，在气道收缩力处于中间值时，实质介导的气道间相互作用对于任何程度的气道间距都可能很大。迄今为止的证据表明，连续体模型可能能更好地体现实质，这表明实质不会介导狭窄气道之间的显著相互作用。
