Dupuis J, Goresky C A, Juneau C, Calderone A, Rouleau J L, Rose C P, Goresky S
McGill University Medical Clinic, Montreal General Hospital, Quebec, Canada.
J Appl Physiol (1985). 1990 Feb;68(2):700-13. doi: 10.1152/jappl.1990.68.2.700.
We used the multiple indicator-dilution technique with norepinephrine, a vascular endothelium surface marker, to study the pulmonary vascular changes in awake exercising dogs. The vascular space tracers, labeled erythrocytes and albumin, and a water space tracer, 1,8-octanediol, were injected with the norepinephrine, and right atrium-aortic root dilution curves were obtained in nine dogs, at rest and at two increasing levels of exercise. Extravascular lung water multiple tracer dilutional estimates increased with flow and rapidly approached a maximal asymptotic value representing 75% of the postmortem lung weight. The ratio of the extravascular lung water measured in this way to that measured gravimetrically also increased, to reach an asymptotic proportion of close to 100%. The transit time-defined central vascular space increased linearly with flow; the ratio of lung tissue space to lung vascular space, therefore, decreased with increasing flow. The mean tracer upslope norepinephrine extractions at rest and at the two levels of exercise were 17 +/- 1.2, 14 +/- 0.8, and 15 +/- 0.8% (SE). With the use of the Crone approximation, we computed permeability-surface area products for norepinephrine; these increased linearly with flow. If permeability does not change, the increase in the permeability-surface area product with flow can be attributed to capillary recruitment. We conclude that when all lung tissue has become accessible to 1,8-octanediol delivered via the perfused vascular space, there is nevertheless further recruitment, with increase in flow, of vascular surface that can extract norepinephrine.
我们采用多指示剂稀释技术，使用血管内皮表面标志物去甲肾上腺素，来研究清醒运动犬的肺血管变化。将血管空间示踪剂（标记红细胞和白蛋白）以及水空间示踪剂1,8 - 辛二醇与去甲肾上腺素一同注入，在9只犬处于静息状态以及两种递增运动水平时获取右心房 - 主动脉根部稀释曲线。血管外肺水的多示踪剂稀释估计值随流量增加而升高，并迅速接近一个最大渐近值，该值相当于死后肺重量的75%。通过这种方式测得的血管外肺水与重量法测得的血管外肺水的比值也升高，达到接近100%的渐近比例。通过转运时间定义的中心血管空间随流量呈线性增加；因此，肺组织空间与肺血管空间的比值随流量增加而降低。在静息状态以及两个运动水平下，示踪剂上升斜率的去甲肾上腺素平均提取率分别为17±1.2%、14±0.8%和15±0.8%（标准误）。使用克朗近似法，我们计算了去甲肾上腺素的通透表面积乘积；这些乘积随流量呈线性增加。如果通透性不变，通透表面积乘积随流量的增加可归因于毛细血管的募集。我们得出结论，当所有肺组织都可通过灌注血管空间获得1,8 - 辛二醇时，然而随着流量增加，仍有可提取去甲肾上腺素的血管表面进一步募集。
