慢性风湿性心脏病Ca^(2+)转运功能的变化与心功能的关系

Alterations in cardiac sacroplasmic reticulum Ca^2+ transport and their relationship with cardiac function in patients with rheumatic heart disease

目的：探讨慢性风湿性心脏病（风心病）慢性心衰时心肌细胞内肌浆网（ＳＲ）Ｃａ２＋转运功能的变化与心功能的关系。方法：采用草酸盐易化的ＳＲＣａ２＋摄取法和测定“裸露”心肌束的咖啡因敏感性的方法，分别测定心肌ＳＲＣａ２＋摄取和释放功能。采用彩超测定左心收缩功能指标左室平均周边缩短速率（ｍＶｃｆ）以及舒张功能指标左室快速充盈分数（ＲＦＦ）和快速充盈期平均左室周边伸长速度（ＲＦｍＶｃｆ）。结果：心肌匀浆ＳＲＣａ２＋摄取量和摄取率风心病组（ｎ＝１９）均显著低于对照组（ｎ＝６）（Ｐ＜０．０５～０．０１），并且ＳＲＣａ２＋摄取率的变化分别与ＲＦＦ和ＲＦｍＶｃｆ的变化密切相关（分别ｒ＝０．６８和ｒ＝０．６４，ｎ＝１１，Ｐ＜０．０５）。“裸露”心肌束的ＳＲ释放Ｃａ２＋速率也明显低于正常水平，且ＳＲ释放Ｃａ２＋的速率变化与ｍＶｃｆ的变化密切相关（ｒ＝０．７５，ｎ＝８，Ｐ＜０．０５）。结论：风心病慢性心衰时存在心肌细胞内ＳＲＣａ２＋摄取和释放功能的下降，并且可能是导致心脏收缩和舒张功能下降的主要环节之一。

Objective: To explore the relationship between the changes of cardiac sacroplasmic reticulum (SR) Ca^2+ transport and cardiac function in patients with rheumatic heart disease (RHD). Methods: SR Ca^2+ uptake was measured by the method of “oxalatefacilitated Ca2+ uptake” . SR Ca2+ release activity was monitored indirectly by measurement of caffeine sensitivity of chemically skinned myocardial fibers. Cardiac function indexes including the mean velocity circumferential fiber shortening (mVcf), rapid filling fraction (RFF) and mean velocity circumferential fiber lengthening during rapid filling period (RFmVcf) were evaluated by two dimensional echocardiography preoperatively. Results: The amount and the rates of SR Ca^2+ uptake in homogenates of cardiomyocytes were significantly lower in patients with RHD than that in controls, and the velocities of SR Ca^2+ release of skinned myocardial fibers in patients with RHD were lower markedly as compared with the normal levels. Moreover, the rates of SR Ca^2+ uptake correlated well with the changes of preoperative RFmVcf (r=0.64, P<0.05) and RFF (r=0.68, P<0.05) in patients with RHD, respectively, and the changes of SR Ca^2+ release function correlated well with the changes of preoperative mVcf in patients with RHD (r=0.75, P<0.05). Conclusion: The functions of both SR Ca^2+ uptake and release are abnormal in cardiomyocytes from patients with RHD, which are important causes of the reduction in cardiac function.