甲亢大鼠心肌细胞缩短幅值-频率关系的变化  

Changes of shortening amplitude-frequency relationship in hyperthyroid rat cardiomyocytes

作　　者：王云英[1] 余志斌[1] 焦博[1] 张子泰[2] 邓敬兰[2] 

机构地区：[1]第四军医大学航空航天生理学教研室,陕西西安710032 [2]第四军医大学西京医院核医学科,陕西西安710032

出　　处：《中国病理生理杂志》2008年第12期2306-2310,共5页Chinese Journal of Pathophysiology

基　　金：国家自然科学基金资助项目(No.30370538)

摘　　要：目的:观测实验性甲状腺功能亢进症(甲亢)大鼠不同时期心功能变化的特征,以探明甲亢大鼠心力衰竭的可能机制。方法:采用大鼠无创尾套法测量血压与脉率,离体工作心脏模型观测心功能,利用离体单心肌细胞测量心肌收缩性能的变化。结果:实验性甲亢大鼠心率明显增快,心肌细胞宽度增加而长度未见明显改变。2周甲状腺素(T4)处理组离体工作心脏模式下,心输出量较对照组明显增强;在固有心率下,前负荷对心功能的调节机制保持正常。2周T4处理组心肌细胞无负荷缩短幅值,在1与2 Hz较对照组显著增加,但在4 Hz下与对照组无差别;随刺激频率增大,缩短幅值逐步降低。4周T4组心肌细胞缩短幅值进一步增大,亦呈随频率增加而幅值降低的现象。两个T4组心肌细胞收缩时程均较对照组明显缩短。在1与2 Hz作用下,心肌细胞的无负荷缩短与舒张速率均明显高于对照组;4 Hz下2周T4组缩短与舒张速率仍高于对照组,4周T4组则与对照组间无显著差别。结论:4周甲亢大鼠单心肌细胞无负荷缩短幅值-频率关系早于整体心脏功能发生变化。AIM： The aim of this study was to observe the cardiac performance in 2 - week or 4 - week levothyroxine （T4） - induced cardiac hypertrophy and to elucidate the possible underlying mechanism of cardiac hypertrophy transition to heart failure in T4 treatment rats. METHODS ： The blood pressure and pulse rate were measured by tail - cuff technique. The cardiac output and the preload - cardiac output were measured in working heart mode. The shortening of unloading contraction in cardiomyocytes was observed by an edge - detector system. RESULTS ： Resting heart rate in T4 treatment rats increased significantly and the width of cardiomyocytes widened in T4 rats, but the length of cardiomyocytes had no difference compared with control values. The cardiac output in 2 - week T4 group was higher than that in control group. The cardiac output increased when the preload increased from 5 mmHg to 15 mmHg. The unloading shortening am- plitude at 1 Hz and 2 Hz increased in 2 - week T4 group. No difference between 2 - week T4 group and control group at 4 Hz was observed. When the stimulating frequency increased from 1 Hz to 4 Hz, the shortening amplitude also increased in control cardiomyocytes, but decreased in 2 - week or 4 - week T4 group. The shortening amplitude increased further in 4 -week T4 group as compared with that in control. The time to peak shortening and time from peak shortening to 75% relaxation reduced at each frequency in 2 - week and 4 - week T4 group. The shortening and relaxation rates in 2 - week or 4 - week T4 group were higher than those in control group at 1 Hz and 2 Hz. The shortening and relaxation rate kept higher at 4 Hz in 2 - week T4 group, but showed no difference with control at 4 Hz in 4 - week T4 group. CONCLUSION ： These above results suggest that shortening amplitude - frequency relationship of cardiomyocytes in 4 - week T4 rats is earlier to be altered than cardiac performance in working heart.

关 键 词：甲状腺功能亢进症 心肌细胞 心肌收缩 

分 类 号：R331[医药卫生—人体生理学]