Zhao Yong-hui, Cui Chang-cong, Li Yu, Huang Chen
Department of Cardiology, Henan Provincial People's Hospital, Zhengzhou 450003, China.
Zhonghua Xin Xue Guan Bing Za Zhi. 2009 Oct;37(10):931-5.
To explore the effects of eukaryotic expression vector pcDNA3-HERG transfection on angiotensin II (Ang II) induced myocyte hypertrophy in cultured neonatal rabbit ventricular myocytes.
Neonatal rabbit ventricular myocytes and eukaryotic expression vector pcDNA3-HERG transfected ventricular myocytes were cultured in Dulbecco's-modified Eagle medium (DMEM), containing 1% fetal bovine serum (FBS) for 6 h, then stimulated with Ang II (10(-7) mol/L) for 48 h. Control ventricular myocytes were cultured in Dulbecco's-modified Eagle medium (DMEM), containing 1% fetal bovine serum (FBS) for 54 h. At 6 and 54 h, myocyte hypertrophic parameters including myocyte volume, total protein content and membrane capacitance, action potential duration (APD) and Calcineurin (CaN) activity were measured.
Compared to control myocytes, APD at 90% repolarization (APD(90)) was prolonged by 19.8% (P < 0.01), without signs of myocyte hypertrophy at 6 h post Ang II stimulation, APD(90) was prolonged by 22.1% (P < 0.01), myocyte volume, total protein content and membrane capacitance and CaN activity were significantly increased by 40.4%, 40.4%, 38.2% and 114.7% respectively (all P < 0.01) at 48 h after Ang II stimulation. HERG gene transfection upregulated I(HERG) tail current (3.6-fold higher than I(Kr)-rapidly activating delayed rectifier potassium current, P < 0.01). HERG gene transfection also accelerated and repolarization and a shortened APD(90) and inhibited myocyte hypertrophy and CaN activation induced by Ang II.
Ang II induced prolongation of APD(90) is directly associated with myocyte hypertrophy by increasing the Ca(2+) influx and resulting in the increment of intracellular Ca(2+) and activation of CaN reaction pathway.
探讨真核表达载体pcDNA3-HERG转染对血管紧张素II（Ang II）诱导的新生兔心室肌细胞肥大的影响。
将新生兔心室肌细胞和经真核表达载体pcDNA3-HERG转染的心室肌细胞在含1%胎牛血清（FBS）的杜尔贝科改良伊格尔培养基（DMEM）中培养6小时，然后用Ang II（10⁻⁷mol/L）刺激48小时。对照心室肌细胞在含1%胎牛血清（FBS）的杜尔贝科改良伊格尔培养基（DMEM）中培养54小时。在6小时和54小时时，测量心肌肥厚参数，包括心肌细胞体积、总蛋白含量和膜电容、动作电位时程（APD）和钙调神经磷酸酶（CaN）活性。
与对照心肌细胞相比，在Ang II刺激后6小时，90%复极化时的APD（APD₉₀）延长了19.8%（P<0.01），无心肌细胞肥大迹象；在Ang II刺激后48小时，APD₉₀延长了22.1%（P<0.01），心肌细胞体积、总蛋白含量、膜电容和CaN活性分别显著增加了40.4%、40.4%、38.2%和114.7%（均P<0.01）。HERG基因转染上调了HERG尾电流（比快速激活延迟整流钾电流I(Kr)高3.6倍，P<0.01）。HERG基因转染还加速了复极化，缩短了APD₉₀，并抑制了Ang II诱导的心肌细胞肥大和CaN激活。
Ang II诱导的APD₉₀延长与心肌细胞肥大直接相关，其机制是增加Ca²⁺内流，导致细胞内Ca²⁺增加并激活CaN反应途径。
