射血分数保留的心力衰竭大鼠心脏锌积累和内质网应激的诱导

Zinc accumulation and endoplasmic reticulum stress induction in heart failure rats with ejection fraction retention

目的在建立射血分数保留心力衰竭(HFpEF)大鼠模型的基础上,检测HFpEF大鼠心肌锌离子浓度及锌转运体Zip14表达的改变以及证实HFpEF大鼠心肌内质网应激和炎症的存在。方法采用达尔盐敏感大鼠(DSS)高盐饮食建立HFpEF动物模型,DSS大鼠随机分为高盐饮食组(HS组)和正常饮食组(NS组)。各组动物均每两周测量一次无创血压和心率,分别在第6周、12周、19周检测两组大鼠的心脏超声指标。麻醉并处死符合HFpEF模型标准以及同时期对照组的大鼠,快速分离左心室心肌并-80℃冰箱保存。应用电感耦合等离子原子发射光谱法(ICP-OES)测定心肌组织的锌离子浓度。RT-fq-PCR和WB分别检测心肌组织锌转运体Zip14的mRNA和蛋白表达水平。研究进一步使用RT-fq-PCR法检测心肌组织内质网应激相关因子ATF6、ATF4、CHOP、Bip和xBPI的mRNA表达水平。WB法检测内质网应激相关因子CHOP、Bip和炎症相关转录因子NF-κB p65的蛋白表达水平。结果在第19周时,与正常饮食组相比,高盐饮食组DSS大鼠的SBP、LVM和LVM/W明显升高,而两组EF比较,差异无统计学意义。HFpEF组大鼠心肌组织的锌离子浓度明显高于对照组。HFpEF组大鼠心肌组织的锌转运体Zip14mRNA和蛋白表达水平明显高于对照组。与对照组相比,HFpEF组大鼠心肌组织的ATF6、ATF4、CHOP、Bip和xBPI的mRNA表达水平明显升高。与对照组相比,HFpEF组大鼠心肌组织的CHOP、Bip和NF-κB p65的蛋白表达水平明显升高。结论 HFpEF大鼠心肌的锌积累与锌转运体Zip14的表达上调、内质网应激以及炎症有一定的相关性,然而,相互之间的具体调节机制有待进一步研究。

Objective To establish a model of heart failure with preserved ejection fraction(HFpEF)in rats and to measure variation in zinc contents and expression levels of Zip14 in myo-cardial of HFpEF rats.Besides,to confirm the existences of endoplasmic reticulum stress and inflammation.Methods In order to establish HFpEF rat model,we choose Dahl salt-sensitive(DSS)rats and fed a high salt diet to experimental group(HFpEF-group).However,the control group was fed a normal salt diet.Blood pressure and heart rate were measured by the noninvasive blood pressure detector every two weeks.In sixth weeks,12 weeks and 19 weeks respectively,the rats were detected by animal specific ultrasound.To detect variation in zinc contents and expression levels of Zip14 in myocardial of HFpEF rats,The left ventricular myocardium specimens were extracted from the successful HFpEF model rat and the control group of corresponding time.The zinc levels of specimens were measured by Inductively Coupled Plasma Optical Emission Spectroscopy(ICP-OES).RT-fq-PCR and Western blot were used to detect mRNA and protein expression of Zip14 in the myocardium.To clarify the existences of endoplasmic reticulum stress and inflammation,RT-fq-PCR was used to detect mRNA expression levels of signal molecules of endoplasmic reticulum stress in myocardium.Western blot was used to detect protein expression levels of CHOP,Bip and inflammation transcription factor NF-κB p65.Results The mean SBP,LVM and LVM/W in HFpEF-group was significantly higher than that in the control-group but did not,however,show a significant difference with EF in 19 th weeks.Compared to the control group,Zip14 mRNA and protein expression levels in the HFpEF rat heart were markedly increased.Besides,the zinc contents in rat heart tissue was significantly increased in HFpEF group when compared to control group.The mRNA expression levels of ATF6,ATF4,CHOP,Bip and xBPI was significantly higher in HFpEFgroup than control-group.The expression levels of CHOP,Bip and NF-κB p65 in HFpEF rat heart were significantly increased compared to those of the controls.Conclusion Zinc accumulation of the HFpEF rat heart were correlated with up-regulation of Zip14 expression,ER stress and inflammatory.However,the exact mechanism of these interactions needs to be further investigated.