氧化应激促进AGT-REN双转基因高血压小鼠心肌中电导钙激活钾离子通道表达

 目的:探讨心肌重构过程中心肌中电导钙激活钾离子通道(K_Ca3.1)蛋白表达与氧化应激反应之间的关系。方法:雄性血管紧张素-肾素(AGT-REN)双转基因高血压(dTH)小鼠2、4、8、12月龄各6只进行相应指标检测。另取12只6月龄雄性dTH小鼠,随机分为2组:模型组(dTH组)和N-乙酰半胱氨酸(NAC)组。同时取6只dTH同品系野生C57B6小鼠作为对照(WT组)。NAC组小鼠腹腔注射NAC 400 mg·kg^-1·d^-1,WT和dTH组小鼠腹腔注射等量生理盐水。4周后检测各组小鼠血压变化;ELISA法测定小鼠血浆中AngⅡ和Ang(1-7)含量变化;试剂盒检测心肌组织超氧化物歧化酶(SOD)活性及丙二醛(MDA)含量;Western blot法检测小鼠心肌胶原蛋白collagen I、collagen III及K_Ca3.1蛋白表达的变化。结果:dTH组小鼠血压、血浆AngⅡ、MDA及胶原蛋白含量均高于同龄WT组小鼠(2月龄除外),并随年龄增长而增高(P<0.05);血浆Ang(1-7)和心肌SOD活性随年龄增长下降,并低于同龄WT组小鼠(2月龄除外)(P<0.05)。NAC干预使6月龄dTH小鼠心肌SOD活性增强(P<0.01),同时心肌MDA、胶原蛋白和K_Ca3.1蛋白表达下降(P<0.05)。结论:高血压所致心肌重构过程中心肌K_Ca3.1蛋白表达增加可能与心肌氧化应激水平增强有关。

Oxidative stress promotes KCa3.1 expression in myocardium of AGT-REN double transgenic hypertension mice

AIM: To study the relationship between oxidative stress reaction and K_Ca3.1 protein expression in the process of myocardial remodeling.METHODS: The male AGT-REN double transgenic hypertension (dTH) mice (2, 4, 8 and 12 months old, each n=6) were used to detect the changes of the corresponding indexes. The male dTH mice (6 months old) were randomly divided into 2 groups: dTH group and N-acetylcysteine (NAC) group, and 6 wild-type(WT) C57B6 mice served as controls. The mice in NAC group were treated with NAC at dose of 400 mg·kg^-1·d^-1, and the WT and model mice were treated with normal saline. After 4 weeks, the concentrations of Ang Ⅱ and Ang (1-7) in the plasma were measured by ELISA. The superoxide dismutase (SOD) activity and malondialdehyde (MDA) content were detected using SOD and MDA kits. The protein levels of collagen I, collagen III and K_Ca3.1 were determined by Western blot. RESULTS: Compared with the WT mice, mean arterial blood pressure (MAP), concentration of Ang Ⅱ in the plasma, the content of MDA, and the protein expression of collagens and K_Ca3.1 in the myocardium of 4-, 8- and 12-month-old dTH mice were increased, and gradually raised along with the age from 2 to 12 months (P<0.05), but the SOD activity in myocardium and Ang (1-7) content in plasma were decreased (P<0.01). NAC reduced the MAP, the content of MDA, and the protein expression of collagens and K_Ca3.1 in the myocardium of 6-month-old dTH mice (P<0.05 or P<0.01), and increased SOD activity compared with dTH group (P<0.01).CONCLUSION: Increased protein expression of myocardial K_Ca3.1 during myocardial remodeling induced by hypertension may be associated with enhancement of myocardial oxidative stress level.