细胞内游离钙在运动心脏重塑中的作用

本文建立了运动心脏的实验动物模型，应用激光扫描共聚焦显微镜与新一代钙荧光指示剂Ｆｌｕｏ－３／ＡＭ的方法，对心肌活细胞内具有生物活性的游离钙的动态变化进行了研究，以期了解运动心脏结构与功能重塑的细胞机制。结果显示：经过１２周耐力训练后，心肌细胞内游离钙浓度静息值无显著性改变，心肌收缩时其游离钙浓度峰值较对照组显著增高１１％（Ｐ＜０．０５）。停止训练８周后，心肌收缩时胞内游离钙浓度峰值较训练时显著降低１４％（Ｐ＜０．０５），恢复到正常对照水平。研究结果提示，运动心脏可保持细胞内钙稳态，心肌收缩时收缩结构钙可获得量增多，是运动心脏心肌收缩性增强的重要机制之一，同时，心肌细胞内游离钙的增多对于运动心脏肥大的发生也起重要的介导作用，而且，运动心肌细胞内游离钙的改变是一种可逆性变化。

The Roles of Myocardial Intracellular FreeCa~(2 ) in Athletic Heart Remodel

In order to investigate the developing mechanism of the structural and functional remodelling in athletic heart, the dynamic changes of the intracellular free Ca~(2 ) were determined in single insolated ventricular myocyte under the laser scanning confocal microscopy . 40 male SD rats were randomly divided into endurance running group , deconditioning group and their sedentary control groups . After conditioning and deconditioning , the living single ventricular myocytes were attained by mean of enzyme perfusion and were loaded by calcium fluorescence indicator Fluo-3/AM , and then the changes of intracelular free Ca~(2 ) were analyzed under the laser scanning confocal microscopy . The results showed that after conditioning , there were no significant changes in myocardialCa~(2 )]i basal values, but the myocardialCa~(2 ])i peak valves were significantly increased 11% as Compared with their controls(P<0.05). After deconditioning, the myocardialCa2 ]i peak values were sig- nificalntly decreased 14% as compared with the conditioning group ( P< 0 . 05 ) , and there were no significant differences with their controls . The results suggested that there was a intracellular calcium homeostasis in athletic heart and the calcium supplement to myocardial contractile elements was increased while heart contrac- tion , and it was one of important mechanisms for increased contractility in athletic heart . The elevated myocardialCa~(2 )]i peak level might be a signal linking for exercise induced cardiac hypertrophy.Also,the changes of myocardial intracellular free calcium in athletic heart were reversible while deconditioning.