Long Chao-liang, Zhang Yan-fang, Yin Zhao-yun, Wang Hai
Institute of Toxicology and Pharmacology, Academy of Military Medical Sciences, Beijing, China.
Space Med Med Eng (Beijing). 2005 Aug;18(4):267-70.
To study the effect of acute hypoxia and hypoxic acclimatization on myocardial function of rats.
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.
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.
研究急性缺氧及缺氧习服对大鼠心肌功能的影响。
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。
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。
这些结果表明，心肌SR钙泵功能增强、PLB磷酸化增强以减轻钙泵抑制作用以及SR中Ca²⁺转运功能增强是缺氧习服保护心脏功能免受严重缺氧损伤的机制。
