[低氧习服对大鼠心肌肌浆网ATP酶及45Ca2+摄取的影响]

[Effects of hypoxic acclimatization on myocardial sarcoplasmic reticulum ATPase and 45Ca2+ uptake in rats].

作者信息

Long Chao-liang, Zhang Yan-fang, Yin Zhao-yun, Wang Hai

机构信息

Institute of Toxicology and Pharmacology, Academy of Military Medical Sciences, Beijing, China.

出版信息

Space Med Med Eng (Beijing). 2005 Aug;18(4):267-70.

PMID:16224849

Abstract

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 (8000 m) for 4 h before and after intermittent hypoxic acclimatization (3000 m and 5000 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, Ca2+, Mg2(+)-ATPase in SR, phosphorylation of phospholamban (PLB) and the ability of 45Ca2+ uptake in SR were observed in all these three groups.

RESULT

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 Ca2+, Mg2(+)-ATPase in myocardial SR of rats after acute hypoxia was reduced significantly (P<0.01). After intermittent hypoxic acclimatization, its activity increased significantly as compared with that of acute hypoxic rats (P<0.01). 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 suggests that hypoxic acclimatization could alleviate the inhibition of calcium pump. 4) The ability of 45Ca2+ 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 Ca2+ transport in SR are the mechanisms of hypoxic acclimatization protecting cardiac functions from injury induced by severe hypoxia.

摘要

目的

研究急性缺氧及缺氧习服对大鼠心肌功能的影响。

方法

将18只雄性Wistar大鼠随机分为三组：常氧对照组、急性缺氧组和间歇性缺氧习服组（n = 6）。在间歇性缺氧习服（分别在3000米和5000米，每天4小时，共14天）前后，使大鼠暴露于8000米海拔缺氧环境4小时，然后断头处死大鼠，从心肌中分离出心肌肌浆网（SR）。观察三组大鼠SR中Na⁺、K⁺ - ATP酶、Ca²⁺、Mg²⁺ - ATP酶的活性、受磷蛋白（PLB）的磷酸化水平以及SR对⁴⁵Ca²⁺的摄取能力。

结果

1）缺氧对大鼠心肌SR中Na⁺、K⁺ - ATP酶的活性无影响。2）与常氧对照组大鼠相比，急性缺氧后大鼠心肌SR中Ca²⁺、Mg²⁺ - ATP酶的活性显著降低（P < 0.01）。间歇性缺氧习服后，其活性与急性缺氧大鼠相比显著升高（P < 0.01）。3）急性缺氧大鼠PLB的磷酸化水平与常氧对照组大鼠相比显著降低。间歇性缺氧习服后，其磷酸化水平与急性缺氧大鼠相比显著升高。这表明缺氧习服可减轻钙泵的抑制作用。4）急性缺氧大鼠SR对⁴⁵Ca²⁺的摄取能力显著降低。缺氧习服后，其摄取能力显著增强。