Melsom M N, Flatebø T, Sjaastad O V, Aulie A, Nicolaysen G
Department of Physiology, Institute of Basic Medical Sciences, University of Oslo, Norway.
Acta Physiol Scand. 1999 Mar;165(3):283-92. doi: 10.1046/j.1365-201x.1999.00492.x.
Considerable heterogeneity unrelated to the effect of gravity has been demonstrated for both local ventilation (V) and perfusion (Q) in the lung. Local ventilation and perfusion are well matched, so that the heterogeneity of the V/Q ratio is less than for ventilation or perfusion alone (Melsom et aL 1997). We are searching for the mechanisms responsible for the coordinate heterogeneity of ventilation and perfusion. Here, we ask how and to what extent physical exercise induces changes in the distribution of ventilation and perfusion. We measured local (approximately 1.5 cm3 tissue volume) pulmonary ventilation and perfusion simultaneously in six sheep before, during and after running on a treadmill. Local ventilation was determined from the deposition of labelled aerosol particles and local perfusion from trapping of radioactive microspheres. Cardiac output increased approximately 2.5-fold during exercise. V/Q-ratios were not normally distributed and we therefore present the heterogeneity as the interquartile range. At rest, the average interquartile ranges for local ventilation, perfusion and V/Q-ratio were 0.48, 0.51 and 0.39, respectively. During exercise, the corresponding values were 0.44, 0.40 and 0.32. Thus, the distribution of local V/Q-ratio was narrower than for ventilation and perfusion also during exercise. We found a moderate redistribution of relative flow towards the dorsal parts of the lungs when perfusion increased, but the increase in total perfusion and ventilation was for the most part throughout the lung. The results indicate that the coupling between local ventilation and perfusion is at least as potent during exercise as at rest. The correlation (r) between paired values in the two resting periods was 0.93 for ventilation and 0.91 for perfusion and thus indicates time stability for the two variables.
肺部局部通气（V）和灌注（Q）已被证明存在与重力影响无关的显著异质性。局部通气和灌注匹配良好，因此V/Q比值的异质性小于单独的通气或灌注（Melsom等人，1997年）。我们正在寻找导致通气和灌注协调性异质性的机制。在此，我们探讨体育锻炼如何以及在多大程度上引起通气和灌注分布的变化。我们在六只绵羊在跑步机上跑步前、跑步期间和跑步后同时测量了局部（约1.5立方厘米组织体积）肺通气和灌注。局部通气通过标记气溶胶颗粒的沉积来确定，局部灌注通过放射性微球的捕获来确定。运动期间心输出量增加约2.5倍。V/Q比值呈非正态分布，因此我们将异质性表示为四分位间距。静息时，局部通气、灌注和V/Q比值的平均四分位间距分别为0.48、0.51和0.39。运动期间，相应的值分别为0.44、0.40和0.32。因此，即使在运动期间，局部V/Q比值的分布也比通气和灌注的分布更窄。我们发现当灌注增加时，相对血流向肺背侧部分有适度的重新分布，但总灌注和通气的增加在很大程度上是整个肺的。结果表明，局部通气和灌注之间的耦合在运动期间至少与静息时一样有效。两个静息期配对值之间的相关性（r），通气为0.93，灌注为0.91，因此表明这两个变量具有时间稳定性。
