Postlethwait E M, Langford S D, Bidani A
Department of Internal Medicine, University of Texas Medical Branch, Galveston 77550.
J Appl Physiol (1985). 1990 Aug;69(2):523-31. doi: 10.1152/jappl.1990.69.2.523.
In a previous study (J. Appl. Physiol. 68: 594-603, 1990) in isolated rat lungs, we suggested that the rate of pulmonary air space absorption of inhaled NO2 is limited, in part, by chemical reaction(s) rather than by physical solubility. Because the initial site of primary absorption interactions involves the epithelial lining fluid (ELF), we investigated whether ELF-NO2 interactions could account for pulmonary NO2 reactive absorption. Rat ELF, obtained by bronchoalveolar lavage (BAL), was compared with a model chemical system (reduced glutathione, GSH). In vitro exposures (NO2-air) used constant gas flow and planar gas-liquid interfaces. 1) Solvent pH notably altered NO2 uptake by GSH but to a lesser extent by BAL. 2) Uptake displayed [GSH]-dependent saturation. [ELF] in BAL was augmented by sequential lavage (lavagate reuse) of multiple lungs. Uptake was proportional to [ELF] but did not saturate under these exposure conditions. 3) The uptake rate exhibited [NO2] dependence. However, relative to increasing [NO2], fractional uptakes decreased for BAL and 1 mM GSH but not for 10 mM GSH. 4) Altered convective gas flow produced nonlinear increments in uptake (10 mM GSH) and substantial decrements in fractional uptake. 5) Arrhenius plots [ln(r) vs. 1/T, where r is reaction rate and T is absolute temperature (degree K)] for BAL and 1 mM GSH yielded respective activation energies of 4,952 and 4,149 kcal.g-1.mol-1 and degree of change in the rate of NO2 uptake per 10 degrees C (Q10) of 1.32 and 1.25. These results imply that the rate of NO2 uptake into rat ELF, like intact lung, is limited, in part, by chemical reaction(s).(ABSTRACT TRUNCATED AT 250 WORDS)
在之前一项针对离体大鼠肺脏的研究（《应用生理学杂志》68: 594 - 603, 1990）中，我们提出吸入的二氧化氮在肺内气腔的吸收速率部分受化学反应而非物理溶解度限制。由于主要吸收相互作用的初始部位涉及上皮衬液（ELF），我们研究了ELF与二氧化氮的相互作用是否能解释肺内二氧化氮的反应性吸收。通过支气管肺泡灌洗（BAL）获取大鼠ELF，并与一种化学模型系统（还原型谷胱甘肽，GSH）进行比较。体外暴露（二氧化氮 - 空气）采用恒定气流和平面气 - 液界面。1）溶剂pH显著改变了GSH对二氧化氮的摄取，但对BAL的影响较小。2）摄取表现出依赖于[GSH]的饱和现象。通过对多个肺脏进行连续灌洗（灌洗液重复使用），BAL中的[ELF]增加。摄取与[ELF]成正比，但在这些暴露条件下未达到饱和。3）摄取速率表现出对[二氧化氮]的依赖性。然而，相对于[二氧化氮]的增加，BAL和1 mM GSH的摄取分数下降，而10 mM GSH则不然。4）改变对流气流会使摄取量产生非线性增加（10 mM GSH），并使摄取分数大幅下降。5）BAL和1 mM GSH的阿伦尼乌斯图[ln(r)对1/T，其中r为反应速率，T为绝对温度（开尔文度）]分别得出活化能为4,952和4,149千卡·克⁻¹·摩尔⁻¹，以及每10摄氏度二氧化氮摄取速率的变化程度（Q10）为1.32和1.25。这些结果表明，二氧化氮摄取到大鼠ELF中的速率，如同在完整肺脏中一样，部分受化学反应限制。（摘要截选至250字）
