Schürch S, Gehr P, Im Hof V, Geiser M, Green F
Respiratory Research Group, University of Calgary, Alberta, Canada.
Respir Physiol. 1990 Apr;80(1):17-32. doi: 10.1016/0034-5687(90)90003-h.
This study was designed to investigate the early stages of particle deposition on airway and alveolar surfaces. To do this we used morphometric studies of aerosol deposition, in situ measurements of surface tension, and in vitro assays of particle displacement and mathematical modelling. We observed that latex particles, equal or less than 6 microns in diameter deposited in hamster lungs were submerged in the subphase of the alveolar lining layer and became completely coated with an osmiophilic film. Similar results were obtained for particles deposited in the conductive airways which were also covered with a surface active film, having a surface tension of 32 +/- 2 dyn.cm-1. In vitro experiments showed that pulmonary surfactant promotes the displacement of particles from air to the aqueous phase and that the extent of particle immersion depends on the surface tension of the surface active film. The lower the surface tension the greater is the immersion of the particles into the aqueous subphase. Mathematical analysis of the forces acting on a particle deposited on an air-fluid interface show that for small particles (less than 100 microns) the surface tension force is several orders of magnitude greater than forces related to gravity. Thus, even at the relatively high surface tension obtained in the airways (32 +/- 2 dyn.cm-1) particles will still be displaced into the aqueous subphase. Particles in peripheral airways and alveoli likely are below the surfactant film and submerged in the subphase. This may promote clearance by macrophages. In addition, particle displacement into the subphase is likely to increase the contact between the epithelial cell and particle. Toxic or allergenic particles would be available to interact with epithelial cells and this may be important in the pathophysiology of airway disease.
本研究旨在调查颗粒在气道和肺泡表面沉积的早期阶段。为此，我们采用了气溶胶沉积的形态计量学研究、表面张力的原位测量、颗粒位移的体外测定以及数学建模。我们观察到，直径等于或小于6微米的乳胶颗粒沉积在仓鼠肺中后，会浸没在肺泡衬里层的亚相中，并完全被一层嗜锇膜覆盖。沉积在传导气道中的颗粒也得到了类似的结果，这些颗粒同样被一层表面活性膜覆盖，其表面张力为32±2达因·厘米⁻¹。体外实验表明，肺表面活性剂促进颗粒从气相转移到水相，并且颗粒的浸没程度取决于表面活性膜的表面张力。表面张力越低，颗粒浸入水相亚相的程度就越大。对作用于沉积在气液界面上的颗粒的力进行数学分析表明，对于小颗粒（小于100微米），表面张力力比与重力相关的力大几个数量级。因此，即使在气道中获得的相对较高的表面张力（32±2达因·厘米⁻¹）下，颗粒仍会被转移到水相亚相中。外周气道和肺泡中的颗粒可能位于表面活性剂膜下方并浸没在亚相中。这可能会促进巨噬细胞的清除作用。此外，颗粒转移到亚相中可能会增加上皮细胞与颗粒之间的接触。有毒或致敏颗粒可能会与上皮细胞相互作用，这在气道疾病的病理生理学中可能很重要。
