Curran-Everett D C, McAndrews K, Krasney J A
J Appl Physiol (1985). 1986 Dec;61(6):2136-43. doi: 10.1152/jappl.1986.61.6.2136.
The effects of acute hypoxia on regional pulmonary perfusion have been studied previously in anesthetized, artificially ventilated sheep (J. Appl. Physiol. 56: 338-342, 1984). That study indicated that a rise in pulmonary arterial pressure was associated with a shift of pulmonary blood flow toward dorsal (nondependent) areas of the lung. This study examined the relationship between the pulmonary arterial pressor response and regional pulmonary blood flow in five conscious, standing ewes during 96 h of normobaric hypoxia. The sheep were made hypoxic by N2 dilution in an environmental chamber [arterial O2 tension (PaO2) = 37-42 Torr, arterial CO2 tension (PaCO2) = 25-30 Torr]. Regional pulmonary blood flow was calculated by injecting 15-micron radiolabeled microspheres into the superior vena cava during normoxia and at 24-h intervals of hypoxia. Pulmonary arterial pressure increased from 12 Torr during normoxia to 19-22 Torr throughout hypoxia (alpha less than 0.049). Pulmonary blood flow, expressed as %QCO or ml X min-1 X g-1, did not shift among dorsal and ventral regions during hypoxia (alpha greater than 0.25); nor were there interlobar shifts of blood flow (alpha greater than 0.10). These data suggest that conscious, standing sheep do not demonstrate a shift in pulmonary blood flow during 96 h of normobaric hypoxia even though pulmonary arterial pressure rises 7-10 Torr. We question whether global hypoxic pulmonary vasoconstriction is, by itself, beneficial to the sheep.
急性缺氧对局部肺灌注的影响此前已在麻醉、人工通气的绵羊身上进行过研究（《应用生理学杂志》56: 338 - 342, 1984）。该研究表明，肺动脉压升高与肺血流向肺背侧（非下垂）区域转移有关。本研究检测了5只清醒、站立的母羊在常压低氧96小时期间肺动脉升压反应与局部肺血流之间的关系。通过在环境舱内用氮气稀释使绵羊处于低氧状态[动脉血氧分压（PaO2）= 37 - 42托，动脉血二氧化碳分压（PaCO2）= 25 - 30托]。在常氧状态下以及低氧状态下每隔24小时，通过向上腔静脉注射15微米放射性标记微球来计算局部肺血流。肺动脉压从常氧状态下的12托升至整个低氧期间的19 - 22托（α < 0.049）。以%QCO或ml×min-1×g-1表示的肺血流在低氧期间并未在背侧和腹侧区域之间发生转移（α > 0.25）；也没有肺叶间的血流转移（α > 0.10）。这些数据表明，清醒、站立的绵羊在常压低氧96小时期间，即使肺动脉压升高7 - 10托，肺血流也不会发生转移。我们质疑全身性缺氧性肺血管收缩本身对绵羊是否有益。
