甲状腺素对大鼠心肌T型钙通道蛋白和mRNA的影响

摘要

AIM:To observe the effect of thyroxine on the expression of T-type calcium channels Cav3. 1, Cav3. 2 and Cav3. 3 in rat myocardium, and to explore the possible biological mechanism between the changes of the ex-pression of T-type calcium channels and the arrhythmia in hyperthyroid heart disease. METHODS:Healthy SD rats (n=20) were randomly divided into normal control group (n=10) and hyperthyroid heart disease group (n=10). The animal model was established by intraperitoneal injection of levothyroxine for 35 d. The contents of T3 and T4 in serum, the heart-to-body weight ratio, the diameter of cardiac myocytes and electrocardiograph were measured to evaluate hyperthyroid heart disease. Moreover, the mRNA and protein expression levels of T-type calcium channels in the myocardium were measured by RT-PCR, immunohistochemistry and Western blot. RESULTS:After intraperitoneal injection of levothyroxine for 35 d, compared with the normal control group, the serum contents of T3 and T4, the heart-to-body weight ratio and the diameter of cardiac myocytes were significantly increased in hyperthyroid heart disease group (P<0.05), and arrhythmia occurred in hyperthyroid heart disease group. By immunohistochemistry and Western blot, the protein expression of Cav3. 1 in-creased significantly (P<0.05), while the protein expression of Cav3.2 decreased significantly (P<0.01). However, no change of the Cav3. 3 protein was observed. The results of RT-PCR were the same as immunohistochemistry and Western blot. CONCLUSION:Thyroxine promotes the expression of Cav3. 1 in the myocardium but inhibits the expression of Cav3. 2 at mRNA and protein levels, which might be involved in arrhythmia in hyperthyroid heart disease.%目的:观察甲状腺素对大鼠心肌T型钙通道Cav3. 1、Cav3. 2和Cav3. 3表达的影响,探讨T型钙通道表达变化与甲亢性心脏病引起的心律失常之间的关系.方法:选取健康SD大鼠20只,随机分为正常对照组和甲亢性心脏病组(n=10),腹腔注射L-甲状腺素(0.5 mg/kg)连续35 d 建立大鼠甲亢性心脏病模型.检测各组大鼠血清T3和T4的含量,测定各组大鼠心脏指数和心肌细胞横径,并行心电图检查;免疫组化和Western blot检测各组大鼠心肌T型钙通道蛋白的表达;RT-PCR检测心肌T型钙通道mRNA的表达.结果:造模35 d后与正常对照组比较,甲亢性心脏病组大鼠血清T3和T4含量明显升高,心脏指数和心肌细胞横径明显增加( P<0.05),并发生心律失常;免疫组化、Western blot和RT-PCR结果显示,甲亢性心脏病组大鼠心肌Cav3. 1表达较正常对照组明显增加(P<0.05),Cav3.2表达明显减少(P<0.01),Cav3.3的表达无变化.结论:甲状腺素可促进心肌Cav3.1 mRNA和蛋白的表达,抑制Cav3.2 mRNA和蛋白的表达,而对Cav3.3的表达则没有影响. Cav3.1和Cav3.2的表达变化可能与甲亢性心脏病心律失常的发生有关.