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目的:探讨在高脂血症状态下,大鼠心电图的变化情况,及高胆固醇血症对心肌电生理特性影响的机制。方法:将20只Wistar大鼠随机分为空白对照组和高脂饮食组,喂养10周后,检测大鼠的血脂水平、心电图和室颤阈值,并通过全细胞膜片钳记录心室肌细胞的ICa,L;利用组织病理学方法评价对照组及高脂饮食组的大鼠动脉粥样硬化的程度。结果:高脂饮食组的大鼠血脂水平与对照组相比明显增高(P<0.01);在高脂饮食组的大鼠动脉血管管壁中,可见广泛分布的粥样硬化斑块。在高脂饮食组的大鼠心电图中,室颤阈值为(4.23±0.12)V,明显低于对照组(12.80±6.34)V,P<0.05。高脂饮食组大鼠的QTc间期(94±16)ms,与对照组(67±12)ms相比明显延长,P<0.05。高脂饮食组大鼠的心室肌细胞的ICa,L密度为(12.83±3.28)pA/pF,与对照组(9.21±2.16)pA/pF相比明显高,P<0.05。结论:高脂饮食后,大鼠的心电图有明显变化,QTc间期延长;高胆固醇血症能明显增加大鼠心肌细胞的ICa,L的,延长复极时程,降低室颤阈值。
AIM: To investigate the changes of electrocardiogram (ECG) and the mechanism of hypercholesterolemia in electrophysiological characteristics of rats under hyperlipidemia. Methods: Twenty Wistar rats were randomly divided into blank control group and high-fat diet group. After 10 weeks of feeding, serum lipids, electrocardiogram and ventricular fibrillation threshold were measured. Whole-cell patch-clamp was used to record ICa, L; The histopathological method was used to evaluate the degree of atherosclerosis in the control group and the high-fat diet group. Results: The level of serum lipids in high-fat diet group was significantly higher than that in control group (P <0.01). In high-fat diet group, widely distributed atherosclerotic plaques were found in the arterial wall of rats. In the electrocardiogram of rats in the high-fat diet group, the threshold of ventricular fibrillation was (4.23 ± 0.12) V, which was significantly lower than that of the control group (12.80 ± 6.34) V, P <0.05. The QTc interval (94 ± 16) ms in the high-fat diet group was significantly longer than that in the control group (67 ± 12) ms, P <0.05. The density of ICa and L of ventricular myocytes in high-fat diet group was (12.83 ± 3.28) pA / pF, which was significantly higher than that in control group (9.21 ± 2.16) pA / pF, P <0.05. CONCLUSION: After high-fat diet, the electrocardiogram of rats changed significantly and the QTc interval prolonged. Hypercholesterolemia could obviously increase the ICa, L of rat myocardial cells, prolong the duration of repolarization and decrease the threshold of ventricular fibrillation.