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目的:研究甲状腺素对单个心肌细胞收缩功能及钙瞬变的影响。方法:SD大鼠60只随机分为对照组(30只)、甲状腺素组(30只)。通过给予甲状腺素喂养后,测量血流动力学指标,随后分离单个心室细胞,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并与对照组比较。结果:(1)甲状腺素治疗组左室收缩压(LVSP)和最大缩短和复长速率(±dp/dtmax)较对照组明显提高(P<0.05),左室舒张末压(LVEDP)较对照组明显下降(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)较对照组明显增加(P<0.05),钙瞬变指标fura-2萤光强度变化(△FFI)明显增强、Ca2+离子达峰值时程(TTPCa)、舒张期Ca2+减少50%时程(T50DCa)较对照组明显缩短(P<0.05)。结论:甲状腺素可改善大鼠心脏功能并增强单个心肌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 study the effect of thyroxine on contractile function and calcium transients of single cardiac myocytes. Methods: Sixty SD rats were randomly divided into control group (30) and thyroxine group (30). After feeding thyroxine, hemodynamic parameters were measured, and then single ventricular cells were isolated. The changes of rat cardiac myocytes contractility and calcium transients were detected synchronously by visual motorized detection system and compared with the control group. Results: (1) LVSP and ± dp / dtmax increased significantly (P <0.05) and left ventricular end-diastolic pressure (LVEDP) in thyroxine-treated group was significantly higher than that in control group Group decreased significantly (P <0.05). (2) The maximal contractile amplitude (PTA), maximal shortening and the rate of growth (± dL / dtmax) of single cardiac myocytes in thyroxine treatment group were significantly higher than those in control group (P <0.05) Fluorescence intensity (△ FFI) was significantly increased. The peak time course (TTPCa) and diastolic Ca2 + decreased 50% (T50DCa) compared with the control group (P <0.05). CONCLUSION: Thyroxine can improve cardiac function and enhance the contractile function and amplitude of calcium transients in single myocardium. It provides an experimental basis for exploring the mechanism of thyroid hormone in treating chronic heart failure at the single cell level.