Effros R M, Murphy C, Hacker A, Schapira R M, Bongard R
Department of Medicine, Medical College of Wisconsin, Milwaukee 53226.
J Appl Physiol (1985). 1994 Sep;77(3):1460-5. doi: 10.1152/jappl.1994.77.3.1460.
The use of methylene blue (MB) to estimate dilution of epithelial lining fluid, which occurs during bronchoalveolar lavage (BAL), is complicated by loss of this redox dye from the air spaces. The rate of MB uptake from the air spaces of isolated rat lungs and the effects of oxidation and reduction on this process were investigated in this study. Movement of MB from the air spaces to perfusate was compared with the corresponding transport of 125I-labeled albumin, [14C]-dextran, 99mTc-labeled diethylenetriaminepentaacetate, [3H]-sucrose, and 3H2O. By the end of 2 min, MB concentrations in the BAL had fallen by 58 +/- 4% (SE; n = 11) and 3H2O by 78 +/- 2% (n = 13), whereas concentrations of the other indicators decreased by approximately 6%. All but 10% of the 3H2O lost from the air spaces was found in the perfusate, whereas 19% of the lost MB was not recovered in the perfusate, suggesting retention of MB in the pulmonary tissues. Absorption of MB from the air spaces was slowed by 20% when the lungs were left unperfused, and absorption was accelerated threefold by reduction of MB to leukomethylene blue with Na2S2O4. In contrast, MB losses from the air space were slowed by the oxidizing agent K3Fe(CN)6 and by addition of superoxide dismutase or ascorbic oxidase. It is therefore possible that ascorbic acid and O2- entering the air spaces reduce MB to the uncharged leuko form. Lowering the pH of the BAL fluid to 3.5 also slowed MB reabsorption. This suggests that acid aspiration may stimulate release of oxidants into the air spaces.
在支气管肺泡灌洗（BAL）过程中，利用亚甲蓝（MB）来估算上皮衬液的稀释情况时，由于该氧化还原染料从气腔中流失，这一过程变得复杂。本研究调查了MB从离体大鼠肺脏气腔的摄取速率以及氧化和还原对该过程的影响。将MB从气腔向灌流液的移动与125I标记白蛋白、[14C] - 葡聚糖、99mTc标记二乙三胺五乙酸、[3H] - 蔗糖和3H2O的相应转运进行了比较。到2分钟结束时，BAL中MB浓度下降了58±4%（标准误；n = 11），3H2O下降了78±2%（n = 13），而其他指标的浓度下降了约6%。从气腔中流失的3H2O除10%外均在灌流液中被发现，而流失的MB中有19%未在灌流液中回收，这表明MB保留在肺组织中。当肺不进行灌流时，MB从气腔的吸收减慢了20%，用Na2S2O4将MB还原为无色亚甲蓝时，吸收加速了三倍。相比之下，氧化剂K3Fe(CN)6以及添加超氧化物歧化酶或抗坏血酸氧化酶可减缓MB从气腔中的流失。因此，有可能进入气腔的抗坏血酸和O2- 将MB还原为不带电荷的无色形式。将BAL液的pH值降至3.5也减缓了MB的重吸收。这表明酸性吸入可能刺激氧化剂释放到气腔中。
