摘要
目的研究低氧习服对大鼠心肌功能的影响。方法18只雄性Wistar大鼠,随机分为常氧对照组、急性低氧组和间断低氧习服组3组,每组n=6。经间断低氧习服(先后模拟海拔3000m和5000m低氧各14d,每天4h,最后8000m低氧4h)和急性低氧(模拟海拔8000m低氧4h)的大鼠,断头处死,迅速取出心脏,分离心肌浆网SR,用水解磷酸根法测定ATP酶活性,用γ-32Pi参入法测定PLB的磷酸化,用微孔滤膜过滤技术测定ATP依赖性心肌SR45Ca2+摄取功能。结果1)低氧对大鼠心肌SRNa+,K+-ATPase的活性无明显影响;2)急性低氧大鼠心肌SRCa2+,Mg2+-ATPase活性较正常大鼠显著降低(P<0.01),而低氧习服大鼠心肌SRCa2+,Mg2+-ATPase活性则较未习服者明显为高(P<0.01),接近正常水平;3)急性低氧大鼠心肌SRPLB的磷酸化显著减弱,而低氧习服大鼠PLB的磷酸化则明显提高,表明低氧习服可减轻对钙泵的抑制;4)急性低氧可显著抑制心肌SR对45Ca2+的摄取,而低氧习服时,SR摄取45Ca2+的能力显著增强,最大摄取量显著增高。结论低氧习服可以明显提高心肌SRCa2+,Mg2+-ATPase及钙泵的活性,从而提高心肌收缩和舒张功能。
Objective To study the effect of acute hypoxia and hypoxic acclimatization on myocardial function of rats. Method Eighteen male Wistar rats were randomly divided into three groups： normoxic control, acute hypoxia and intermittent hypoxic acclimatization group （n =6）. After being exposed to hypoxia （8 000 m） for 4 h before and after intermittent hypoxic acclimatization （3 000 m and 5 000 m, 14 d respectively, 4 h/d） ,the rats were decapitated and then myocardial sarcoplasmic reticulum （SR） were derived from cardiac muscles. Activities of Na^＋ , K^＋-ATPase, Ca^2＋ , Mg^2＋-ATPase in SR, phosphorylation of phospholamban （PLB） and the ability of ^45Ca^2＋ uptake in SR were observed in all these three groups. Result l ） Hypoxia had no effects on the activity of Na^＋ , K^＋-ATPase in rats myocardial SR of rats. 2） Compared with normoxic control rats, the activity of Ca^2＋,Mg^2＋-ATPase in myocardial SR of rats after acute hypoxia was reduced significantly（P 〈0.0l ）. After intermittent hypoxic acclimatization, its activity increased significantly as compared with that of acute hypoxic rats（P 〈0.0l ）. 3） The phosphorylation of PLB in acute hypoxic rats was reduced significantly compared with normoxic control rats. After intermittent hypoxic acclimatization,its phosphorylation was increased significantly compared with that of acute hypoxic rats, It suggestes that hypoxic acclimatization could alleviate the inhibition of calcium pump. 4） The ability of ^45Ca^2＋ uptake of SR in acute hypoxic rats was decreased significantly, After hypoxic acclimatization, its ability was strengthened significantly. Conclusion These results suggest that the increased function of myocardial SR calcium pump, the strengthened phosphorylation of PLB to alleviate the inhibition of calcium pump and the increased function of Ca^2＋ transport in SR are the mechanisms of hypoxic acclimatization protecting cardiac functions from injury induced by severe hypoxia.
出处
《航天医学与医学工程》
CAS
CSCD
北大核心
2005年第4期267-270,共4页
Space Medicine & Medical Engineering
基金
国家自然科学基金重点项目(39730190)
军队医药卫生科研基金重点课题(01Z025)
关键词
低氧习服
心肌
肌浆网
磷酸受纳蛋白
钙摄取
hypoxic acclimatization
myocardium
sarcoplasmic reticulum
phospholamban
Ca^2＋ uptake
