间断短时供氧的时长与高度对其防护低压低氧大鼠肺动脉高压作用的影响

Effects of the duration and physiological equivalent altitude of intermittent short-time oxygen supply on its protective effect against pulmonary hypertension in rats with hypobaric hypoxia

目的比较间断短时供氧防护方法在不同供氧时长与生理等效高度等情况下对慢性低压缺氧所致大鼠肺动脉高压防护作用的影响。方法实验选用健康SD雄性大鼠48只,随机分为6组:对照组(CON组),慢性缺氧组(H组),间断短时供氧I15、I10、I5、I3K组。CON组大鼠实验全程生活在地面正常环境,H组和间断短时供氧组大鼠均通过动物低压舱全程生活在5000 m低气压环境中,但间断短时供氧组大鼠每日间断短时供氧3次,每次间隔均等时间,其中I15、I10、I5组单次供氧时长分别为1.5、1.0、0.5 h,供氧生理等效高度为地面高度;I3K组单次供氧时长为1.0 h,供氧生理等效高度为3000 m。2周后,比较大鼠体质量,测量大鼠心脏质量、左心质量、血细胞比容(HCT)、右心室收缩压(反映肺动脉压)、右心室肥厚指数、肺含水量等,同时检测血清与肺组织中丙二醛(MDA)含量。结果H组及间断短时供氧组大鼠体质量均明显下降(P<0.01),但I15组体质量明显高于其他供氧组(P<0.05)。H组及间断短时供氧组大鼠HCT明显高于对照组(P<0.01),但各供氧组均低于H组(P<0.05),各供氧组间无明显差异。各组心脏质量与体质量比值和左心质量与体质量比值无明显差异。与CON组相比,各组大鼠右心肥厚指数及右心室收缩压均明显升高(P<0.01),但I10组与I5组升高幅度明显低于H组(P<0.05),且此两组间无明显差异,而I15组及I3K组大鼠与H组相比无明显差异。各组大鼠肺含水量无明显差异。与CON组相比,各组大鼠血清与肺组织中MDA含量均明显升高(P<0.05),且各供氧组大鼠明显高于H组大鼠(P<0.05),而I15组升高幅度又明显高于其他供氧组(P<0.05)。结论实验结果提示间断短时供氧1 h与0.5 h具有相当的防护效果,单次供氧时长1.5 h防护效果下降,防护效果可能与氧化应激水平的变化有关。当供氧高度为3000 m时,间断短时供氧无明显防护效果。供氧时长与供氧高度的影响在不同生理系统可能不同。

Objective To compare the protective effects of intermittent short-time oxygen supply on pulmonary hypertension induced by chronic hypobaric hypoxia in rats under different oxygen supply duration and physiological equivalent altitude.Methods Forty-eight healthy male SD rats were randomly divided into 6 groups:control group,chronic hypoxia group and intermittent short-time oxygen supply I15,I10,I5 and I3K groups.The rats in the control group lived in the normal environment on the ground throughout the experiment,while the rats in the chronic hypoxia group and the intermittent short-time oxygen supply groups all lived in the hypobaric hypoxia environment of 5000 m using the animal altitude chamber.However,the rats in the intermittent short-time oxygen supply groups were provided with intermittent short-time oxygen supply three times a day,with an equal interval.Among them,the single oxygen supply duration of I15,I10 and I5 groups was 1.5,1.0,0.5 h,respectively,and the physiological equivalent altitude of oxygen supply was the sea level.In the I3K group,the single oxygen supply duration was 1.0 h,and the physiological equivalent altitude of oxygen supply was 3000 m.After two weeks,the body mass of the rats was compared,and the heart mass,left heart mass,hematocrit(HCT),right ventricular systolic pressure(reflecting pulmonary artery pressure),right ventricular hypertrophy index and lung water content were measured.At the same time,the malondialdehyde(MDA)content in serum and lung tissue was detected.Results The body mass of rats in hypoxia group and intermittent short-term oxygen supply groups was significantly decreased(P<0.01),but the body mass of rats in I15 group was significantly higher than that of other oxygen supply groups(P<0.05).The HCT of rats in hypoxia group and intermittent short-term oxygen supply groups was significantly higher than that in control group(P<0.01),but the HCT in all oxygen supply groups was lower than that in chronic hypoxia group(P<0.05),and there was no significant difference among all oxygen supply groups.There was no significant difference in the ratio of heart mass to body mass and the ratio of left heart mass to body mass among all groups.Compared with the control group,the right ventricular hypertrophy index and right ventricular systolic pressure of rats in other groups were significantly increased(P<0.01),but the increase amplitude of I10 group and I5 group was significantly lower than that of chronic hypoxia group(P<0.05),and there was no significant difference between the two groups,while there was no significant difference between I15 group and I3K group and chronic hypoxia group.There was no significant difference in lung water content among all groups.Compared with the control group,the content of MDA in serum and lung tissue of rats in all groups was significantly increased(P<0.05),and the content of MDA in oxygen supply groups was significantly higher than that in chronic hypoxia group(P<0.05),while the increase in I15 group was significantly higher than that in other oxygen supply groups(P<0.05).Conclusion The results suggest that intermittent short-term oxygen supply for 1 h and 0.5 h has a similar protective effect,but the protective effect decreases for a single oxygen supply for 1.5 h,which may be related to the change of oxidative stress level.The intermittent short-time oxygen supply at physiological equivalent altitude of 3000 m has no significant protective effect.The effects of oxygen supply duration and oxygen supply physiological equivalent altitude may be different in different physiological systems.