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目的研究甲状腺素对心力衰竭大鼠的单个心肌细胞收缩功能及钙瞬变的影响。方法采用腹主动脉缩窄法建立大鼠心力衰竭模型,随机分为心衰组与甲状腺素治疗组,另设假手术对照组。术后16周测定心功能。各组分离单个心室细胞,采用可视化动缘探测系统同步检测大鼠心肌细胞收缩和钙瞬变的变化。结果①甲状腺素治疗组左室收缩压(LVSP)和±dp/dtmax较CHF组明显提高(P<0.05),左室舒张末压(LVEDP)较CHF组明显下降(P<0.05)。②甲状腺素治疗组单个心肌细胞收缩功能指标最大收缩幅度(PTA)、最大缩短和复长速率(±dL/dtmax)较CHF组明显增加(P<0.05),钙瞬变指标fura-2荧光强度变化(ΔFFI)增强、Ca2+离子达峰值时程(TTPCa)、舒张期Ca2+减少50%时程(T50DCa)较CHF组明显缩短(P<0.05)。结论甲状腺素可改善大鼠单个心衰细胞的收缩功能及钙瞬变幅度,在单细胞水平上为探讨甲状腺素治疗慢性心衰的发生机制提供了实验依据。
Objective To investigate the effect of thyroxine on contractile function and calcium transient of single cardiomyocytes in rats with heart failure. Methods A rat model of heart failure was established by abdominal aorta constriction. The model was randomly divided into heart failure group and thyroxine treatment group. A sham operation control group was also established. Cardiac function was measured 16 weeks after surgery. Each group isolated a single ventricular cells, synchronous detection of myocardial contractility and calcium transient changes using visual moving detection system. Results ① The LVSP and ± dp / dtmax in thyroxine group were significantly higher than those in CHF group (P <0.05), and LVEDP was significantly lower than that in CHF group (P <0.05). ② Compared with CHF group, the maximal contractility (PTA), maximal shortening and long-term growth rate (± dL / dtmax) of single cardiac myocytes in thyroxine treatment group were significantly increased (P <0.05) (ΔFFI), Ca 2+ ion peak time (TTPCa) and diastolic Ca 2+ decrease 50% (T50DCa) were significantly shorter than CHF group (P <0.05). Conclusions Thyroxine can improve the contractile function and amplitude of calcium transient in single heart failure rats, and provide an experimental basis for exploring the mechanism of thyroid hormone in treating chronic heart failure at the single cell level.