中度急性缺氧对血浆内皮素含量的影响

Effects of Acute Hypobaric Hypoxia on Plasma Endothelin Content in Humans

为了观察急性低压缺氧对人体血浆中内皮素（ＥＴ）含量的影响，将４８名空、地勤人员分为实验组、对照组和动态监测组。ＥＴ浓度用放射免疫法测定。结果发现，缺氧前空、地勤人员的血浆ＥＴ含量基本一致（Ｐ＞０．０５），提示飞行因素对人体血浆ＥＴ的合成与释放无明显影响。急性低压缺氧后，实验组血浆ＥＴ含量明显增加，与对照组相比，差异显著（Ｐ＜０．０５），说明急性中度低压缺氧能够促进血管内皮细胞对ＥＴ的释放。但急性低压缺氧时的血浆ＥＴ升高程度远较病理情况低。轻度的ＥＴ浓度升高，对人体是否会构成重要损害，还需观察确定。

Endothelin(ET)is a bio-active polypeptide synthesized and releasedby vaso-endothelial cells. it is the strongest vasoconstrictive substance ever known inmammalians. High dose of ET may causes serious functional disorders and tissue damagesuch as coronary spasm , myocardial clonus , cardiac arrhythmias , decrease of cardiacoutput , leakage of tissue protein and accumulation of calcium in the myocardial cells.Itwas found in our study , that both single or multiple acute hypoxia could bring about sig-nificant increase of plasma ET content in rats. In order to investigate the effect of acutehypobaric hypoxia upon plasma content of ET in humans , and to provide some objectivereferences for the prevention of damage due to hypoxia , experiments of acute hypobarichypoxia were carried out in 48 healthy pilots and ground personnel. Radioimmunoassaywas used for the determination of ET content , and the ET radioimmunoassay drug boxwas provided by the General Hospital of PLA. Our results showed the plasma ET contentwas 75.2±13.8pg/ml among pilots before hypoxia, and was 71.O±19.3 pg/ml inground personnel, there was no significant difference among them(P<0.05).The re-sults also suggested that flying factors had no remarkable effect on the synthesis and re-lease of human piasma ET. However, the plasma ET content increased remarkably in pi-lot after acute hypobaric hypoxia(88.3± 13.0pg/ml), and there was a significant dif-ference (P<0.05) as compared with that in ground personnel(76.7±11.7pg/ml ).The result suggested that acute moderate hypobaric hypoxia could promote the release ofET by vaso-endothelial cells. The plasma ET level during acute hypoxia was much loweras compered with that in various pathologic conditions. Generally speaking, the plasmaET content in various pathologic conditions could be increased from several times to overten times, while it could only be increased by 15% during acute moderate hypoxia.whether slight increase of ET level has an serious effects on human body is still uncertainand needs further investigetion. In addition, our research also showed that there was noeffect of age on secreation of ET, and ET content in plasma has no obvious rhythmicchange under physiological state.