Miller M A, Hales C A
J Appl Physiol Respir Environ Exerc Physiol. 1980 Nov;49(5):846-50. doi: 10.1152/jappl.1980.49.5.846.
Repeated intermittent global hypoxia has been reported to markedly enhance hypoxic pulmonary vasoconstriction in dogs. We have reexamined this phenomenon but with intermittent unilateral alveolar hypoxia, avoiding complications of systemic hypoxemia. Fifteen anesthetized dogs were intubated with a double-lumen endotracheal tube, allowing separate ventilation of one lung with 100% N2 as a hypoxic challenge and the other lung with 100% O2 to maintain adequate systemic oxygenation. Distribution of lung perfusion was determined with intravenous 133Xe and external chest detectors. Each dog alternately breathed air or the unilateral alveolar hypoxia combination for 15 min each for a total of 12 hypoxic challenges or 6 h. Two groups emerged on the basis of the strength of their vasoconstrictor responses to successive hypoxic challenge. In group I (n = 6), perfusion to the hypoxic lung decreased 29% with the first challenge and decreased comparably with successive challenges. In group II, vasoconstriction was initially weak with perfusion decreasing only 5%, but perfusion decreased further with time alone (n = 5) or successive challenges (n = 4), falling 35% on the 12th challenge (comparable to group I). Delayed achievement of hypoxic vasoconstriction in group II may be secondary to a vasodilating prostanoid that disappears with time.
据报道，反复间歇性全身性缺氧可显著增强犬类的低氧性肺血管收缩。我们重新研究了这一现象，但采用的是间歇性单侧肺泡缺氧，以避免全身性低氧血症的并发症。15只麻醉犬经双腔气管插管，通过向一侧肺通气100%氮气作为低氧刺激，另一侧肺通气100%氧气以维持足够的全身氧合。通过静脉注射133氙和外部胸部探测器来确定肺灌注分布。每只犬交替呼吸空气或单侧肺泡缺氧组合，每次15分钟，共进行12次低氧刺激或6小时。根据对连续低氧刺激的血管收缩反应强度，出现了两组。在第一组（n = 6）中，对低氧肺的灌注在第一次刺激时下降了29%，在连续刺激时下降程度相当。在第二组中，血管收缩最初较弱，灌注仅下降5%，但随着时间推移（n = 5）或连续刺激（n = 4），灌注进一步下降，在第12次刺激时下降了35%（与第一组相当）。第二组中低氧性血管收缩的延迟出现可能继发于一种随着时间消失的血管舒张性前列腺素。
