甲状腺功能减退大鼠心肌抗氧化能力及ATP酶活性的实验研究

Study on the capability of myocardial antioxidation and the activity of ATPase in myocardium of hypothyroid rats

目的 研究甲状腺功能减退大鼠心肌抗氧化能力及心肌膜标志酶活性的变化，探讨甲状腺功能减退致心肌损伤的发病机制。方法 30只Wistar大鼠随机分为对照组和甲状腺功能减退组，用低碘饲料和不含碘的水喂养大鼠复制甲状腺功能减退动物模型。制备心肌组织匀浆，提取心肌生物膜，测定心肌组织丙二醛（MDA）水平、谷胱甘肽过氧化物酶（GSH—Px）和超氧化物歧化酶（SOD）活性及心肌生物膜Na^＋，K^＋-ATP酶、Mg^2＋-ATP酶、Ca^2＋-ATP酶、Ca^2＋，Mg^2＋-ATP酶活性。结果 与对照组比较，甲状腺功能减退组血清T3、T4均明显下降（P〈0．05或〈0．01）：心肌组织MDA水平和GSH—Px活性明显升高（P〈0．05），而SOD活性明显降低（P〈0．05）；心肌生物膜Na^＋，K^＋-ATP酶、Ca^2＋-ATP酶、Mg^2＋-ATP酶、Ca^2＋，Mg^2＋-ATP酶活性明显下降（P〈0．05）。结论 甲状腺功能减退时心肌抗氧化能力下降，心肌过氧化损伤，表现为心肌膜上参与代谢的ATP酶活性降低。

Objective To investigate the changes of the capability of myocardial antioxidation and the activity of myocardium marker enzyme in hypothyroid rats, and to explore the pathogenesis of hypothyroid myocardial damage. Methods Wistar rats were divided into two groups randomly： euthyroid group and hypothyroid group. Wistar rats were rendered hypothyroid by feeding low-iodine test diet and water. The contents of malondialdehyde （MDA） and the levels of free radical scavengers [glutathione peroxidase （GSH-Px） and superoxide dismutase（SOD）] were measured in the myocardium of rats in two groups. The activities of Na^＋,K^＋-ATPase, Ca^2＋-ATPase, Mg^2＋-ATPase and Ca^2＋ ,Mg^2＋-ATPase were determined in the membrane of myocardium in two groups. Results In hypothyroid group, serum T3 was significantly lower（P 〈 0.05 ） than that in euthyroid group and T4 decreased more（P 〈 0.01 ）. The levels of MDA and GSH-Px was increased, but the activity of SOD was significantly decreased （all P 〈 0.05） in hypothyroid group. In hypothyroid group, the activities of Na^＋,K^＋-ATPase, Ca^2＋-ATPase, Mg^2＋-ATPase and Ca^2＋,Mg^2＋- ATPase were obviously lower （all P 〈 0.05 ）. Conclusion In the state of hypothyroid, the capability of myocardial antioxidatio, as well as the activity of ATPase, decreases in rat myocardium, which is contributory to the pathogenesis of hypothyroid myocardial damage.