Tsai Wen-Chin, Lu Yen-Yu, Chen Yao-Chang, Chang Chien-Jung, Kao Yu-Hsun, Lin Yung-Kuo, Chen Yu-Hsin, Chen Shih-Ann, Yang Liang-Yo, Chen Yi-Jen
Division of Cardiology, Tzu-Chi General Hospital, Hualien, Taiwan.
Division of Cardiology, Sijhih Cathay General Hospital, New Taipei City, Taiwan.
Int J Cardiol. 2015 Jun 15;189:172-81. doi: 10.1016/j.ijcard.2015.04.080. Epub 2015 Apr 11.
Sex hormones and calcium (Ca(2+)) regulation play roles in the pathophysiology of ventricular tachycardia from right ventricular outflow tract (RVOT). The purpose of this study was to evaluate whether androgen receptor knockout (ARKO) can increase RVOT arrhythmogenesis through modulating RVOT electrophysiology and Ca(2+) homeostasis.
Conventional microelectrodes were used to study the action potential (AP) in RVOT tissues prepared from wild type (WT) and ARKO mice (aged 6-10 months) before and after caffeine (1mM), isoproterenol (1 μM), adenosine (10 μM) and flecainide (5 μM) administration. The Fluo-3 fluorescence Ca(2+) imaging with confocal microscopy and western blots were used to investigate intracellular Ca(2+) (Ca(2+)i) transients, Ca(2+) sparks, and the expressions of ionic channel proteins in ARKO and WT RVOT myocytes.
We found that ARKO RVOTs (n = 13) had longer AP duration, faster burst firing (5.4 ± 0.7 vs. 3.4 ± 0.7 Hz, P < 0.05), and higher incidence of early afterdepolarizations (82% vs. 8%, P < 0.001) than WT RVOTs (n = 11). Adenosine and flecainide can suppress caffeine- or isoproterenol-induced spontaneous rates and burst firing in WT RVOTs, but not in ARKO RVOTs. ARKO RVOT myocytes had a higher frequency (7.7 ± 2.8 vs. 1.3 ± 0.4 spark/mm/s, P < 0.05) and incidence (89% vs. 47%, P < 0.05) of Ca(2+) sparks, and greater expressions of Cav1.2, NCX, phosphorylated RyR (s2814), phosphorylated phospholamban (Thr17), CAMKII and GRK2 than WT RVOT myocytes. However, ARKO and WT RVOT myocytes exhibit similar Ca(2+)i transients and SR Ca(2+) content, and less expression of calsequestrin.
ARKO changes RVOT electrophysiology and Ca(2+) homeostasis with increased ventricular arrhythmogenesis.
性激素和钙（Ca(2+)）调节在右心室流出道（RVOT）室性心动过速的病理生理学中发挥作用。本研究的目的是评估雄激素受体敲除（ARKO）是否可通过调节RVOT电生理学和Ca(2+)稳态来增加RVOT心律失常的发生。
使用传统微电极研究野生型（WT）和ARKO小鼠（6至10个月龄）在给予咖啡因（1mM）、异丙肾上腺素（1μM）、腺苷（10μM）和氟卡尼（5μM）之前和之后RVOT组织中的动作电位（AP）。使用共聚焦显微镜的Fluo-3荧光Ca(2+)成像和蛋白质印迹法研究ARKO和WT RVOT心肌细胞中的细胞内Ca(2+)（Ca(2+)i）瞬变、Ca(2+)火花以及离子通道蛋白的表达。
我们发现，与WT RVOT（n = 11）相比，ARKO RVOT（n = 13）的AP持续时间更长，爆发性放电更快（5.4±0.7对3.4±0.7 Hz，P < 0.05），早期后去极化发生率更高（82%对8%，P < 0.001）。腺苷和氟卡尼可抑制WT RVOT中咖啡因或异丙肾上腺素诱导的自发频率和爆发性放电，但对ARKO RVOT无效。ARKO RVOT心肌细胞的Ca(2+)火花频率（7.7±2.8对1.3±0.4火花/mm/s，P < 0.05）和发生率（89%对47%，P < 0.05）更高，并且Cav1.2、NCX、磷酸化的RyR（s2814）、磷酸化的受磷蛋白（Thr17）、钙调蛋白激酶II和GRK2的表达高于WT RVOT心肌细胞。然而，ARKO和WT RVOT心肌细胞表现出相似的Ca(2+)i瞬变和肌浆网Ca(2+)含量，并且肌集钙蛋白的表达较少。
ARKO改变RVOT电生理学和Ca(2+)稳态，增加室性心律失常的发生。
