大鼠肥大心肌细胞动作电位、瞬时外向钾离子电流变化及其分子机制  

Changes of action potential and transient outward potassium current in rat hypertrophic myocardial cells and the molecular mechanism

作　　者：范茁 吴振强[1] FAN Zhuo;WU Zhenqiang(School of Bioscience and Bioengineering,South China University of Technology,Guangzhou 510006,China)

机构地区：[1]华南理工大学生物科学与工程学院,广州510006

出　　处：《山东医药》2021年第24期50-53,共4页Shandong Medical Journal

基　　金：国家自然科学基金资助项目(31300940);广东省科技创新战略专项资金项目(2018JK35202003)。

摘　　要：目的观察大鼠肥大心肌细胞动作电位、瞬时外向钾离子电流(Ito)变化,并探讨其分子机制。方法急性分离大鼠心室肌细胞,加入5μmol/L异丙肾上腺素体外孵育24 h诱导心肌细胞肥大(观察组),另加入同等体积去离子水(对照组),采用电流钳技术检测两组心肌细胞动作电位时程,电压钳技术检测心肌细胞Ito幅度、电流密度,qRT-PCR法检测心肌细胞Kv4.2、Kv4.3、KChIP2 mRNA。结果观察组和对照组动作电位时程(APD90值)分别为(68.2±4.1)、(52.0±5.9)ms,两组比较,P<0.05。观察组和对照组在+50 mV刺激电压下的电流幅度分别为543、1 116.1 pA,在+50 mV刺激电压下的电流密度分别为(2.4±0.5)、(5.0±1.0)pA/pF,两组比较,P均<0.05。观察组和对照组Kv4.2 mRNA相对表达量分别为56.2±6.9、100±24.8,Kv4.3 mRNA相对表达量分别为58.5±8.4、100.0±11.1,KChIP2 mRNA相对表达量分别为32.3±7.8、100±15.9,两组比较,P均<0.05。结论大鼠肥大心肌细胞动作电位时程显著延长,Ito显著下降,Kv4.2、Kv4.3、KChIP2等相关离子通道mRNA表达量的降低可能是影响心肌细胞电生理特性改变的分子机制。Objective To observe the changes of action potential and transient outward potassium current(Ito) and to explore the molecular mechanism.Methods Rat ventricular myocytes were isolated acutely and incubated with 5 μmol/L epinephrine for 24 h to induce cardiomyocyte hypertrophy(observation group).The same volume of deionized water was added to the control group.The action potential duration of cardiomyocytes in the two groups was detected by current-clamp technique;Ito amplitude and current density of cardiomyocytes were detected by voltage-clamp technique.The mRNA expression levels of Kv4.2,Kv4.3 and KChIP2 were detected by qRT-PCR.Results The action potential duration(APD90 value) in the observation and control group was(68.2±4.1) and(52.0±5.9) ms,respectively,with statistically significant difference(P<0.05).The current amplitudes of the observation and control group at+50 mV stimulation voltage were 543 and 1 116.1 pA,respectively,and the current densities at+50 mV stimulation voltage were(2.4±0.5) and(5.0±1.0) pA/pF,respectively,with statistically significant difference(allP<0.05).The relative mRNA expression levels of Kv4.2 in the observation and control group were 56.2±6.9 and 100±24.8,respectively,the relative mRNA expression levels of Kv4.3 in the two groups were 58.5±8.4 and 100.0±11.1,respectively,and the relative mRNA expression levels of KChIP2 in the two groups were 32.3±7.8 and 100±15.9,respectively,with statistically significant difference(all P<0.05).Conclusions The action potential duration of hypertrophic cardiomyocytes is significantly longer and the Ito current of hypertrophic cardiomyocytes significantly decreases.The decrease of mRNA expression of related ion channels(Kv4.2,Kv4.3,and KChIP2) may be the molecular mechanism under the changes of electrophysiological characteristics of cardiomyocytes.

关 键 词：心肌细胞动作电位 心肌细胞瞬时外向钾离子电流 心率失常 肥大心肌细胞 

分 类 号：Q424[生物学—神经生物学]