硒对大鼠缺血心肌Ca^(2+)转运功能的影响

Effects of selenium on the Ca^2+ transporting function in rats with ischemic myocardium

目的探讨硒对急性缺血心肌保护作用的机制。方法采用结扎大鼠心肌左冠状动脉复制心肌缺血模型。ＳＤ大鼠１００只，分为正常对照组（Ｃ）、缺血组（ＭＩ）及硒组（ＭＩ＋Ｓｅ）。硒组按每日补硒８０μｇ·ｋｇ－１，连续７ｄ。观察硒对心肌缺血后３０、６０、９０ｍｉｎ肌浆网（ＳＲ）、线粒体（Ｍｉｔ）Ｃａ２＋－ＡＴＰ酶活性动态变化及缺血６０ｍｉｎ肌膜（ＳＬ）Ｎａ＋－Ｋ＋－ＡＴＰ酶活性和线粒体膜磷脂含量变化的影响。结果与正常对照组比较，心肌缺血不同时点，Ｍｉｔ、ＳＲ、Ｃａ２＋－ＡＴＰ酶活性均有不同程度降低，且呈随缺血时间延长进行性下降的趋势；缺血６０ｍｉｎＭｉｔ磷脂含量和ＳＬＮａ＋－Ｋ＋－ＡＴＰ酶活性也明显降低。但无论任何时点，硒组Ｍｉｔ、ＳＲＣａ２＋－ＡＴＰ酶、ＳＬＮａ＋－Ｋ＋－ＡＴＰ酶活性和Ｍｉｔ磷脂含量均显著高于缺血组。结论硒在一定程度上能减轻或延缓缺血对心肌细胞Ｃａ２＋转运功能的损害作用，可能是硒保护急性缺血心肌作用机制之一。

Objective To investigate the protective effects of selenium on acute ischemic myocardium.Methods The model of myocardial ischemia was established by ligating the descending anterior branch of left coronary artery.One hundred Sprague-Dawley rats were divided into three groups:normal control group(C),myocardium ischemic group(MI) and Se-supplement group(MI+Se).The MI+Se group received Se 80μg·kg^-1 daily i.p for 7 days before the left coronary occlusion.The effects of sodium selenite(Se) on the dynamic changes of Ca^2+-ATPase activity of Mitochondria(Mit),Sarcoplasmic reticulum(SR) fractions at 30,60 and 90min after ischemia were determined,and the changes of the Na^+-K^+-ATPase activity of sarcolemma(SL) and Mit phospholipid contents after 60min ischemia MI,MI+Se rat hearts were observed.Results The Ca^2+-ATPase activity of Mit and SR decreased progressively from 30 to 90min after ischemia,depending on duration of ischemia which were associated with reducing SL Na^+-K^+-ATPase activity and Mit phospholspid contents in MI group compared with control.However,the Mit and SR Ca^2+-ATPase activity as well as SL Na^+-K^+-ATPase activity,Mit phospholipid contents were markedly improved when the hearts before ischemia pretreated with sodium selenite in comparision with MI group.Conclusion Selenium can alleviate or delay the ischemic damage to myocardial Ca^2+-transporting function in certain extent.The protecting the myocardial Ca^2+-transporting function are probably one of mechenisms of protective effects of selenium on acute ischemic myocardium.