Hopkins S R, Schoene R B, Henderson W R, Spragg R G, West J B
Department of Medicine, University of California, San Diego, La Jolla, California 92093-0623, USA.
J Appl Physiol (1985). 1998 Apr;84(4):1185-9. doi: 10.1152/jappl.1998.84.4.1185.
The extreme thinness of the pulmonary blood-gas barrier results in high mechanical stresses in the capillary wall when the capillary pressure rises during exercise. We have previously shown that, in elite cyclists, 6-8 min of maximal exercise increase blood-gas barrier permeability and result in higher concentrations of red blood cells, total protein, and leukotriene B4 in bronchoalveolar lavage (BAL) fluid compared with results in sedentary controls. To test the hypothesis that stress failure of the barrier only occurs at the highest level of exercise, we performed BAL in six healthy athletes after 1 h of exercise at 77% of maximal O2 consumption. Controls were eight normal nonathletes who did not exercise before BAL. In contrast with our previous study, we did not find higher concentrations of red blood cells, total protein, and leukotriene B4 in the exercising athletes compared with control subjects. However, higher concentrations of surfactant apoprotein A and a higher surfactant apoprotein A-to-phospholipid ratio were observed in the athletes performing prolonged exercise, compared with both the controls and the athletes from our previous study. These results suggest that, in elite athletes, the integrity of the blood-gas barrier is altered only at extreme levels of exercise.
肺气血屏障极薄，运动时毛细血管压力升高会导致毛细血管壁承受较高的机械应力。我们之前的研究表明，对于精英自行车运动员，与久坐不动的对照组相比，6 - 8分钟的最大运动量会增加气血屏障通透性，并导致支气管肺泡灌洗（BAL）液中红细胞、总蛋白和白三烯B4的浓度升高。为了验证气血屏障的应力衰竭仅在最高运动水平时才会发生这一假设，我们让6名健康运动员在以最大耗氧量的77%运动1小时后进行了BAL。对照组为8名正常非运动员，他们在BAL前未进行运动。与我们之前的研究不同，我们发现与对照组相比，进行运动的运动员的红细胞、总蛋白和白三烯B4浓度并没有升高。然而，与对照组以及我们之前研究中的运动员相比，进行长时间运动的运动员的表面活性物质载脂蛋白A浓度更高，表面活性物质载脂蛋白A与磷脂的比率也更高。这些结果表明，在精英运动员中，气血屏障的完整性仅在极端运动水平时才会改变。
