Overholser K A, Lomangino N A, Parker R E, Pou N A, Harris T R
Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee 37235.
J Appl Physiol (1985). 1994 Aug;77(2):845-55. doi: 10.1152/jappl.1994.77.2.845.
To test the hypothesis that the distribution of hemodynamic resistance is involved in the control of pulmonary capillary surface area, we measured permeability-surface area product (PS) and longitudinal resistance distribution (LRD) as functions of perfusion rate in isolated rabbit lungs under zone II conditions (n = 10) and through the zone II-III transition (n = 4). PS, considered to be indicative of functioning capillary surface area, was measured with the aid of the diffusion-limited tracer [14C]propanediol, whereas LRD was determined using a viscous bolus technique. LRD was seen to change character with increasing flow and increasing PS/surface area, becoming bimodal with low central resistance as full capillary recruitment was approached in zone III. Effects of hypoxic ventilation were studied in zone II in five lungs; it was found that hypoxia altered the LRD and eradicated the normoxic dependence of PS/surface area on perfusion rate. It was concluded that LRD is involved in the determination of functioning capillary surface area.
为了验证血流动力学阻力分布参与肺毛细血管表面积调控这一假说，我们在Ⅱ区条件下（n = 10）以及通过Ⅱ-Ⅲ区转变过程（n = 4），测量了离体兔肺中作为灌注率函数的通透系数-表面积乘积（PS）和纵向阻力分布（LRD）。借助扩散受限示踪剂[14C]丙二醇测量被认为可指示功能性毛细血管表面积的PS，而使用粘性团块技术测定LRD。随着流量增加和PS/表面积增加，LRD的特征发生变化，在Ⅲ区接近完全毛细血管募集时，变为具有低中心阻力的双峰分布。在5个肺的Ⅱ区研究了低氧通气的影响；发现低氧改变了LRD，并消除了PS/表面积对灌注率的常氧依赖性。得出的结论是，LRD参与功能性毛细血管表面积的确定。
