哇巴因对大鼠心脏超微结构及心功能的影响

目的 探索哇巴因对大鼠心脏超微结构及心功能的影响。方法 雄性SD大鼠随机分为哇巴因组和生理盐水对照组，分别给予哇巴因或生理盐水腹腔注射，每周测量收缩压。4周后，对两组动物进行心脏超声检查，并予有创血流动力学检查评估心功能，透射电镜观察心脏超微结构的变化。结果 SD大鼠腹腔注射哇巴因4周后，两组间血压尚无显著差异。心脏超声检查提示，哇巴因组大鼠左心室收缩及舒张末期内径、舒张末期左心室后壁厚度、室间隔厚度以及左心室质量增加，等容舒张时间延长，E／A值、射血分数及左心室短轴缩短率降低，与对照组相比有显著性差异（P〈0．05）。有创血流动力学检查显示，哇巴因组大鼠左心室收缩压、左心室内压最大上升／下降速率降低，左心室舒张压升高。透射电镜观察显示，哇巴因组大鼠心肌细胞肿胀，肌纤维断裂，Z线消失，线粒体增生肿胀，部分空泡化，细胞间胶原纤维增生。结论 哇巴因可引起大鼠左心室增大、室壁增厚、心脏收缩及舒张功能受损，心肌超微结构损伤，此效应发生在血压升高前，提示哇巴因可能有直接的心肌损害作用。

Effect of ouabain on cardiac function and myocardium ultrastructure of rat

Objective To investigate the changes in rat cardiac function and myocardium ultrastructure in response to ouabain treatment. Methods Twenty-four male SD rats were randomized into two equal groups to receive daily intraperitoneal injection of ouabain or saline for 4 consecutive weeks, and their systolic blood pressure (SBP) was recorded weekly. After 4 weeks of injection, echocardiography was performed and the hemodynamic parameters were measured by invasive cardiac catheterization, and the changes in myocardium ultrastructure observed using transmission electron microscopy. Results After 4 weeks of ouabain injection, no significant changes in the mean SBP occurred in comparison with the saline group, but echocardiographic examination showed significant increases in the left ventricular end-diastolic and end-systolic diameters, septum thickness, posterior wall thickness, left ventricular mass and isovolumetric relaxation time but significantly lowered E/A ratio, ejection fraction and fractional shortening after ouabain treatment (P<0.05). Invasive monitoring revealed significant attenuation of the left ventricular developed pressure, rate of pressure development ( dp/dt) and rate of pressure decay (-dp/dt), and increment of the left ventricular end diastolic pressure. Myofibrillar fragmentation, swelling of the cardiac myocytes, absence of the Z line, increases of the mitochondria and collagen fibers were found in ouabain group by transmission electron microscopy. Conclusion Ouabain can induce left ventricular enlargement, cardiac wall thickening, myocardial ultrastructural alterations, systolic and diastolic dysfunction in rats before blood pressure elevation is detected, indicating that ouabain can directly cause cardiac damage in rats.