Prolonged lobar hypoxia in vivo enhances the responsivity of isolated pulmonary veins to hypoxia.
Prolonged lobar hypoxia in vivo enhances the responsivity of isolated pulmonary veins to hypoxia.
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DOI：
10.1164/ajrccm/145.3.640
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发表时间：
1992-03
期刊：
影响因子：
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通讯作者：
D. Sheehan;L. Farhi;J. Russell
中科院分区：
文献类型：
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作者：
D. Sheehan;L. Farhi;J. Russell
本文研究了8只绵羊右肺尖叶（RAL）吸入100%N_2 20 h后离体肺血管的缺氧反应。这些有意识的绵羊的RAL吸入低氧气体，其余的肺吸入空气。在缺氧期间，RAL灌注是其空气值的33 +/- 3%，颈动脉PO 2平均为86 +/- 3 mm Hg，肺灌注压与RAL吸入空气时的初始对照期无显著差异。在低氧暴露结束时，处死绵羊，从RAL和右心叶分离肺动脉和静脉环（内径0.5至2 mm），右心叶用作对照叶（CL）。RAL和CL的动脉对6%O2/6%CO2/88%N2（缺氧）没有反应。相比之下，RAL静脉在缺氧时剧烈收缩，而CL静脉不收缩或仅最小程度地收缩。摩擦内皮或先用过氧化氢酶（1，200单位/ml）、吲哚美辛（10 - 5 M）或血栓素A2/前列腺素H2（TxA 2/PGH 2）受体拮抗剂SQ 29，548（3 × 10 - 6 M）孵育RAL静脉，均显著降低对缺氧的反应。还发现RAL静脉比CL静脉对前列腺素内过氧化物类似物U46619的反应性更强。我们的结论是，长时间的肺叶缺氧在体内增加了反应性的孤立肺静脉缺氧。这些收缩可能是由于活性O2物质的增加，这反过来又改变了TxA 2/PGH 2的产生、代谢和/或组织对TxA 2/PGH 2的反应性。
The hypoxic response of pulmonary vessels isolated from eight sheep whose right apical lobes (RAL) had inspired 100% N2 for 20 h was studied. The RAL of these conscious sheep inspired hypoxic gas and the remainder of the lung inspired air. During hypoxia, RAL perfusion was 33 +/- 3% of its air value, carotid arterial PO2 averaged 86 +/- 3 mm Hg and pulmonary perfusion pressure was not significantly different from the initial control period when the RAL inspired air. At the end of the hypoxic exposure, the sheep were killed, and pulmonary artery and vein rings (0.5 to 2 mm inner diameter) were isolated from both the RAL and the right cardiac lobe, which served as the control lobe (CL). Arteries from the RAL and CL did not contract in response to 6% O2/6% CO2/88% N2 (hypoxia). In contrast, RAL veins did contract vigorously in response to hypoxia, whereas CL veins did not contract or contracted only minimally. Rubbing of the endothelium or prior incubation of RAL veins with catalase (1,200 units/ml), indomethacin (10(-5) M), or the thromboxane A2/prostaglandin H2 (TxA2/PGH2) receptor antagonist, SQ 29,548 (3 X 10(-6) M) each significantly reduced the response to hypoxia. RAL veins were also found to be more reactive than CL veins to the prostaglandin endoperoxide analogue U46619. We conclude that prolonged lobar hypoxia in vivo increases the responsivity of isolated pulmonary veins to hypoxia. These contractions may result from an increase in reactive O2 species, which in turn modify production of, metabolism of, and/or tissue responsivity to TxA2/PGH2.