Roselli R J, Riddle W R
Department of Biomedical Engineering, School of Engineering, Vanderbilt University, Nashville, Tennessee 37235.
J Appl Physiol (1985). 1989 Dec;67(6):2343-50. doi: 10.1152/jappl.1989.67.6.2343.
Several groups of investigators are measuring transcapillary protein flux in the lung using noninvasive methods. Results from these studies are reported using several different protein transport indexes, including pulmonary transvascular transfer coefficient, relative extravascular protein, pulmonary transcapillary escape rate, protein leak index, lung transferrin index, slope index, and lung-to-heart count ratios. The purpose of this study is to discover the relationships between these indexes by employing a two-compartment theory of protein transcapillary transport in the lung. We found that all the above indexes can be related to a single index, which we call the normalized slope index. This index is the time rate of change of radioactivity originating from protein in lung interstitium divided by radioactivity arising from protein in lung plasma, normalized by this ratio at time 0, and corrected for blood volume changes. In particular the normalized slope index is shown to be the same as pulmonary transcapillary escape rate under normal sampling conditions and is relatively unaffected by changes in interstitial volume. The response of the normalized slope index to changes in microvascular pressure and microvascular permeability is explored by applying a two-pore model of the microvascular barrier. Results indicate that the normalized slope index is relatively insensitive to changes in microvascular pressure but is greatly affected by changes in microvascular permeability (i.e., changes in large-pore size or number). Since all published leak indexes are related, we would encourage all investigators in the field to adopt a single leak index. We recommend that when a two-compartment model is applied to external detection data, the results be expressed as pulmonary transcapillary escape rate.(ABSTRACT TRUNCATED AT 250 WORDS)
几组研究人员正在使用非侵入性方法测量肺中的跨毛细血管蛋白通量。这些研究的结果通过几种不同的蛋白质转运指标进行报告，包括肺血管跨膜转运系数、相对血管外蛋白、肺跨毛细血管逸出率、蛋白渗漏指数、肺转铁蛋白指数、斜率指数以及肺与心脏计数比。本研究的目的是通过采用肺中蛋白质跨毛细血管转运的两室理论来发现这些指标之间的关系。我们发现上述所有指标都可以与一个单一指标相关，我们将其称为标准化斜率指数。该指数是肺间质中蛋白质产生的放射性的时间变化率除以肺血浆中蛋白质产生的放射性，以时间0时的该比率进行标准化，并针对血容量变化进行校正。特别是，在正常采样条件下，标准化斜率指数与肺跨毛细血管逸出率相同，并且相对不受间质体积变化的影响。通过应用微血管屏障的双孔模型，探讨了标准化斜率指数对微血管压力和微血管通透性变化的反应。结果表明，标准化斜率指数对微血管压力变化相对不敏感，但受微血管通透性变化（即大孔大小或数量的变化）的影响很大。由于所有已发表的渗漏指数都是相关的，我们鼓励该领域的所有研究人员采用单一的渗漏指数。我们建议，当将两室模型应用于外部检测数据时，结果应以肺跨毛细血管逸出率表示。（摘要截短于250字）
