Hypoxia has a greater effect than exercise on the redistribution of pulmonary blood flow in swine
Hypoxia has a greater effect than exercise on the redistribution of pulmonary blood flow in swine
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DOI：
10.1152/japplphysiol.00306.2007
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发表时间：
2007-12-01
影响因子：
3.3
通讯作者：
Hlastala, Michael P.
中科院分区：
文献类型：
--
作者：
Hopkins, Susan R.;Kleinsasser, Axel;Hlastala, Michael P.
高强度运动与缺氧的结合与高原肺水肿（HAPE）的发展有关，据信这是由继发于高血管压力的肺毛细血管破裂引起的。低氧和运动在改变肺血流量（PBF）分布方面的相对重要性尚不清楚。6只长期插管的无特定病原体的约克郡杂种猪（25.5 +/- 0.7 kg，平均值+/- SD）在常氧（FIO 2 = 0.21）和缺氧（FIO 2 = 0.125，平衡顺序）条件下进行递增平板运动试验，包括在先前测定的VO 2 max的30、60和90%下进行5 min。在稳态（类似于4分钟）下，收集代谢和心输出量数据，并在类似于30秒内注射荧光微球。随后，测定每个2 cm（3）肺片中每种颜色的荧光强度，并根据重量标准化荧光计算区域灌注。缺氧和运动都使PBF从腹侧颅侧肺区域向肺背侧尾侧区域移动，但缺氧引起的PBF在休息时的背侧尾侧移动比在常氧下的近最大运动更大。由于缺氧、运动和血管结构导致的PBF变化分别为16 +/- 4.2、4.0 +/- 4.4和59.4 +/-11.4%，缺氧和运动之间的相互作用代表12 +/-6.5%。这一观察结果意味着，在猪的背尾侧区域，随着缺氧，PBF已经有了最大的变化，这在增加运动的情况下是不能超过的。然而，运动会大大增加肺动脉压，因此增加高流量区域毛细血管破裂的风险。
Strenuous exercise combined with hypoxia is implicated in the development of high-altitude pulmonary edema (HAPE), which is believed to result from rupture of pulmonary capillaries secondary to high vascular pressures. The relative importance of hypoxia and exercise in altering the distribution of pulmonary blood flow (PBF) is unknown. Six chronically catheterized specific pathogen-free Yorkshire hybrid pigs (25.5 +/- 0.7 kg, means +/- SD) underwent incremental treadmill exercise tests in normoxia (FIO2 = 0.21) and hypoxia (FIO2 = 0.125, balanced order), consisting of 5 min at 30, 60, and 90% of the previously determined VO2max. At steady state (similar to 4 min), metabolic and cardiac output data were collected and fluorescent microspheres were injected over similar to 30 s. Later the fluorescent intensity of each color in each 2-cm(3) lung piece was determined and regional perfusion was calculated from the weight-normalized fluorescence. Both hypoxia and exercise shifted PBF away from the ventral cranial lung regions toward the dorsal caudal regions of the lung, but hypoxia caused a greater dorsal caudal shift in PBF at rest than did near-maximal exercise in normoxia. The variance in PBF due to hypoxia, exercise, and vascular structure was 16 +/- 4.2, 4.0 +/- 4.4, and 59.4 +/- 11.4%, respectively, and the interaction between hypoxia and exercise represented 12 +/- 6.5%. This observation implies that there is already a maximal shift with in PBF with hypoxia in the dorsal-caudal regions in pigs that cannot be exceeded with the addition of exercise. However, exercise greatly increases the pulmonary arterial pressures and therefore the risk of capillary rupture in high flow regions.