血栓素和前列环素对清醒山羊在缺氧和空气栓塞时肺血管收缩的作用

16只成年山羊分两组,在清醒状态下进行实验。Ⅰ组单独空气栓塞组,在平原环境中经右心室输入空气,其量为0.05ml/kg/min。Ⅱ组缺氧复合空气栓塞组,在模拟4000m高原停留1h后输入空气,其量和方法与Ⅰ组相同。观察单独缺氧、空气栓塞和缺氧复合空气栓塞的肺动脉平均压((?)pa)、肺血管阻力(PVR)的改变,应用放射免疫方法测定动脉血浆中血栓素和前列环素的稳定代谢产物TXB_2和6-keto-PGF_1α含量,并计数外周动脉血白细胞总数。实验结果提示:缺氧或肺微血管空气栓塞单独作用的早期,肺血管收缩与TXA_2合成、释放增加有关;在急性缺氧所致肺血管张力增高的基础上,输入空气可使PVR进一步增高,但增高的幅度显著低于空气栓塞单独作用时;缺氧时输入空气,虽有PGI_2暂时释放增多,但继之PGI_2合成、释放减少。

The Role of Thromboxane and Prostacyclin in Pulmonary Vasoconstriction under Hypoxia and Air-embolism in Conscious Goats

Sixteen adult goats were divided into 2 groups and were experimented in conscious conditions.The first group received air infusion (0.05ml/mm/kg) into the right ventricle for 4 hours under normal oxygen tension at sea level.The second group received combined injury of hypoxia and air embolism.The animals were put into a simulated altitude of 4 000 meters for one hour then were given air infusion as in group one.Then the changes of the mean pulmonary arterial pressure(Ppa) and pulmonary vascular resistance (PVR) were observed in the animals of both groups.The arterial plasma level of thrornboxane B2(TXB2) and 6-keto-PGF1a,the stable metabolites of thromboxane A2 and prostacyclin,were determined with radio-immunoassay.The leucocytes in the peripheral arterial blood were counted.It was found that in the early stage of hypoxia or air-embolism of the pulmonary vessels,the constriction of pulmonary vessels was related to the synthesis and release of thrornboxne A2; on the basis of increased tension of the pulmonary vessels induced by acute hypoxia,the infusion of air into the right ventricle could further increase the PVR but the amplitude of increment was markedly smaller than that induced by air-embolism alone.Introduction of air under hypo-xic condition would result in a transcient increase of prostacyclin release,but the release of prostacyclin would soon go down to the prehypoxic level