不同生理等效高度的富氧环境对大鼠急进高原肺水肿的防护作用

目的研究不同生理等效高度的富氧环境对大鼠急进高原肺水肿的防护作用。方法50只雄性Wistar大鼠按随机数字表法分为地面对照组、缺氧组、富氧1组、富氧2组及富氧3组，每组10只。除地面对照组外，分别将各实验组大鼠置于实验舱内，均以10m／s的速度上升至气压高度6000m，上升同时缺氧组输入空气，富氧1组和富氧2组分别输入氧浓度35％和30％的富氧气体，富氧3组则每4h交替输入空气与35％富氧气体，流量均为7L／min。24h后实验舱下降至地面，处死大鼠，测肺部含水率及病理学效应，测肺组织匀浆中的内皮素-1浓度和-氧化氮合酶活力。结果地面对照组大鼠肺含水率最低（0．80％±0．01％），与其它各组比差异有统计学意义（P〈0．01）；缺氧组最高（0．83％±0．01％），与地面对照组和富氧3组比差异有统计学意义（P〈0．01）；3个供氧组居中，其中富氧3组以o．81％土0．01％显著低于富氧1组和富氧2组（P〈0．05）。病理结果表明各实验组出现了不同程度肺水肿表现，由重至轻依次为缺氧组、富氧2组、富氧1组和富氧3组。内皮素-1浓度各组间差异无统计学意义。地面对照组一氧化氮合酶活力最高，为（1．49土0．24）U／mg，与其它各组比差异有统计学意义（P〈0．01）；缺氧组最低，为（0．78±0．28）U／mg，富氧1组和富氧3组一氧化氮合酶活力较强，分别为（1．06±0．17）U／mg、（1．09土0．20）U／mg，与缺氧组比较差异有统计学意义（P〈0．01）。结论在6000m停留24h后大鼠出现了高原肺水肿。氧浓度为35％富氧环境（生理等效高度约2500m）能够有效预防肺水肿，而氧浓度为30％的富氧环境（生理等效高度约3500m）防护效果不显著。4h间断供给含氧35％气体同样可以有效预防大鼠在6000m出现的高原肺水肿。

The preventing effect of oxygen enriched environment at physiological equivalent altitudes on the high altitude pulmonary edema of rat

Objective To study the preventing effect of oxygen enriched environment at physiological equivalent altitudes on high altitude pulmonary edema (HAPE) by HAPE animal model Methods Fifty male Wistar rats were randomly and averagely divided into ground control group,hypoxia group,oxygen enrichment group 1,oxygen enrichment group 2 and oxygen enrichment group 3.Groups were exposed to 6000 m with the climbing rate of 10 m/s in altitude chamber,except ground control group.Meanwhile,hypoxia group was supplied with air and oxygen enrichment group 1 and 2 were supplied with gas that contained 35％ and 30％ oxygen respectively.Oxygen enrichment group 3 was alternatively supplied with air or gas that contain 35 ％ oxygen every 4 h with the flow rate of 7 L/min.The chamber was descended to ground level after 24 h experiment.The water ratio of the left lung of rat was examined,the prefrontal lobe of right lung was taken for pathological observing,the middle and posterior lobe of the right lung were taken to detect the concentration of endothelin-1 (ET-1) and nitricoxide synthase (NOS) activity respectively. Results The water ratio of lung among every group presented significant difference.Ground control group showed the lowest water ratio (0.80％± 0.01％) and significantly different with that of other groups (P＜0.01).The water ratio of hypoxia group was 0.83％ + 0.01％,which was significantly higher than that of ground control group and oxygen enrichment group 3 (P＜0.01).The water ratio of rich oxygen group 2 was 0.81％ + 0.01％,which was obviously lower than that of oxygen enrichment group 1 and oxygen enrichment group 3 (P＜0.05).The pathology result showed that the rat lung of all the experiment groups presented severe to mild changes of interstitium pulmonary edema with the sequence of hypoxia group,oxygen enrichment group 2,oxygen enrichment group 1 and oxygen enrichment group 3.And there were no significant ET-1 concentration difference among every group. The NOS activity of ground control group was (1.49±0.24) U/mg,which was the highest in groups (P＜0.01),and the NOS activity of hypoxia group was (0.78 + 0.28) U/mg,which was the lowest among all groups (P＜0.01).Compared with the hypoxia group,the NOS activity of oxygen enrichment group 1 and oxygen enrichment group 3 was more energetic [(1.06 + 0.17) U/mg,(1.09 + 0.20) U/mg,P＜0.01]. Conclusions Serious HAPE happens on the rats that stayed at 6000 m for 24 h.By making 35％ oxygen enriched environment (physiological equivalent altitude of 2500 m) or supplying with 70 mm Hg oxygen partial pressure of inspired air would effectively prevent rat from HAPE.But there is no significant protection effect by supplying with 30％ oxygen concentration (physiological equivalent altitude is 3500 m) or setting up 56 mm Hg oxygen partial pressure of inspired air.Intermittent supplement of 35％ oxygen every 4 h would also effectively prevent rat from HAPE at 6000 m.