间断性高原低氧-复氧对大鼠心脏的影响

Influence of intermittent plateau hypoxia/reoxygenation on rat heart

目的通过观察间断低氧-复氧暴露大鼠心脏结构及血流动力学的变化,了解在高原环境下间断性供氧对大鼠心脏的影响。方法采用低压舱复制高原低氧模型。成年雄性SD大鼠50只,随机分为5组:平原对照组(C组)、慢性低氧组(H组,模拟海拔5000 m低压环境8周)、间断低氧组(I组,除每天上、下午将低压舱模拟海拔高度降至平原2 h,夜晚8 h置于海拔2700 m外,其余同H组)、慢性低氧返回平原1周组(Hw组)、间断低氧返回平原1周组(Iw)。心导管技术测定左、右心室功能,比色法测定心肌超氧化物歧化酶(SOD)活性和丙二醛(MDA)含量。结果大鼠右心室最大压力与右心室肥大指数,H组、I组、Hw组较C组显著升高(P<0.05),但Iw组无显著差异;I组、Iw组分别与H组、Hw组比较显著降低(P<0.05)。与C组比较,H、I、Hw组心室肌SOD活性显著下降(P<0.05);H组MDA含量显著升高(P<0.05),I、Hw与Iw组无显著差异。结论长期高原低氧环境下间断性供氧可减轻大鼠右心室压力和心室肥大程度;减少心肌氧自由基损伤;有利于返回平原后心脏结构和功能恢复。

Objective To understand the influence of intermittent hypoxia/reoxygenation on rat heart in plateau environment through observing the heart structure and hemodynamic changes in rats exposed to intermittent hypoxia/reoxygenation.Methods The model of plateau hypoxia was established by applying hypobaric chamber.Male adult SD rats(n=50)were divided randomly into 5 groups:plain control group(group C),chronic hypoxia group[group H,in simulated lower pressure environment(altitude of 5000 m)for 8 weeks],intermittent hypoxia group(group I,in the same environment as group H,except of reducing simulated altitude to plain for 2 h in the morning and afternoon and setting at 2700 m for 8 h at night every day),1-week chronic hypoxia group(group Hw,returned to plain for 1 week),and 1-week intermittent hypoxia group(group Iw,returned to plain for 1 week).The left ventricular function and right ventricular function were detected by using cardiac catheter,and activity of myocardial superoxide dismutase(SOD)and content of malondialdehyde(MDA)were detected by using colorimetry.Results The right ventricular maximum pressure(RVMP)and right ventricular hypertrophy index increased significantly in group H,group I and group Hw(P<0.05),and had no significant changes in group Iw compared with group C,and they decreased significantly in group I and Iw group compared with group H and group Hw(P<0.05).The activity of SOD decreased significantly in group H,group I and group Hw compared with group C(P<0.05).The content of MDA increased significantly in group H(P<0.05)and had no significant changes in group I,group Hw and group Iw.Conclusion The intermittent oxygen supply in long-term plateau hypoxia environment can reduce right ventricular pressure and relieve ventricular hypertrophy and damage due to oxygen free radicals,which is propitious to the recovery of heart structure and function after returning to plain.