A trial to evaluate the mechanical anisotropy in human lung ; Aim for elucidating why centrilobular type emphysema occurs predominantly at upper lung

目前还不清楚为什么小叶中心肺气肿，与吸烟有关，主要发生在上肺。上肺叶的呼吸运动比下肺叶小。我们假设细胞外基质的重建根据呼吸运动的机械负荷范围而变化。基于这一假设，上肺的机械应力阈值可能低于下肺。在此背景下，我们试图评估人体肺的力学各向异性，以明确力学特性在小叶中心肺气肿发展中的作用。我们制备了人肺冠状板片样。通过切割薄片样品制备用于力学测量的狭缝样品。通过拉伸样品直至其破裂来评估抗机械应力的阈值。因此，上肺的机械拉伸强度低于下肺。提示力学性质的分布可能与小叶中心肺气肿的发生有关。

It has not been elucidated why centrilobular emphysema, associated with cigarette smoke, occurs predominantly at upper lung. Respiratory movement in the upper lobe is smaller than that in the lower lung. We hypothesize that reconstruction of extra cellular matrix varies according to range of mechanical load by respiratory movement. Based on this hypothesis the threshold against mechanical stress in the upper lung may be lower than that in the lower lung. In this context we tried to evaluate mechanical anisotropy in human lung to make clear the role of mechanical property in development of centrilobular emphysema.We prepared sheet samples from coronal plate of human lung. Slit samples for mechanical measurements were prepared by cutting the sheet samples. The threshold against mechanical stress was evaluated by stretching the samples until their breakdown.As a result, the mechanical stretching strength in the upper lung was lower than in the lower lung. This result suggests that the distribution of mechanical property may contribute to the development of centrilobular emphysema.