West J B, Mathieu-Costello O
Department of Medicine, University of California-San Diego, La Jolla 92093-0623, USA.
Proc Assoc Am Physicians. 1998 Nov-Dec;110(6):506-12.
The lung is particularly vulnerable to injury because the blood-gas barrier is so extremely thin. Furthermore, the mechanical stresses in the barrier become very high when capillary pressure is raised, or when the lung is inflated to a high volume. The strength of the blood-gas barrier on the thin side can be attributed to the type IV collagen in the basement membranes. Abnormally high stresses in the walls of the pulmonary capillaries result in ultrastructural changes including disruptions of both the alveolar epithelial and capillary endothelial layers. All Thoroughbred racehorses break their pulmonary capillaries when they gallop. Also, elite human athletes develop changes in the permeability of the blood-gas barrier at high levels of exercise. Pathological conditions resulting in stress failure include: 1) high-altitude pulmonary edema; 2) neurogenic pulmonary edema; 3) severe left ventricular failure; 4) mitral stenosis; and 5) overinflation of the lung. There is a spectrum of low permeability to high permeability edema as the capillary pressure is raised. Remodeling of pulmonary capillaries apparently occurs at high capillary pressures. It is likely that the extracellular matrix of the capillaries is continuously regulated in response to capillary wall stress.
肺特别容易受到损伤，因为气血屏障极其薄。此外，当毛细血管压力升高或肺膨胀到高容量时，屏障中的机械应力会变得非常高。气血屏障薄侧的强度可归因于基底膜中的IV型胶原蛋白。肺毛细血管壁异常高的应力会导致超微结构变化，包括肺泡上皮层和毛细血管内皮细胞层的破坏。所有纯种赛马在疾驰时都会破裂肺毛细血管。此外，优秀的人类运动员在高强度运动时气血屏障的通透性也会发生变化。导致应力衰竭的病理状况包括：1）高原肺水肿；2）神经源性肺水肿；3）严重左心衰竭；4）二尖瓣狭窄；5）肺过度膨胀。随着毛细血管压力升高，会出现从低通透性到高通透性水肿的一系列情况。肺毛细血管重塑显然发生在高毛细血管压力时。毛细血管的细胞外基质可能会根据毛细血管壁应力持续受到调节。
