First Department of Medicine, University Medical Centre Mannheim (UMM), University of Heidelberg, Mannheim, Germany.
DZHK (German Center for Cardiovascular Research), Partner Sites Heidelberg-Mannheim and Göttingen, Germany.
Europace. 2021 Jul 18;23(7):1137-1148. doi: 10.1093/europace/euab008.
This study aimed to investigate possible roles and underlying mechanisms of alpha-adrenoceptor coupled signalling for the pathogenesis of Takotsubo syndrome (TTS).
Human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) were treated with a toxic concentration of epinephrine (Epi, 0.5 mM for 1 h) to mimic the setting of TTS. Patch-clamp technique, polymerase chain reaction (PCR) and Fluorescence-activated cell sorting (FACS) were employed for the study. High concentration Epi suppressed the depolarization velocity, prolonged duration of action potentials and induced arrhythmic events in hiPSC-CMs. The Epi effects were attenuated by an alpha-adrenoceptor blocker (phentolamine), suggesting involvement of alpha-adrenoceptor signalling in arrhythmogenesis related to QT interval prolongation in the setting of TTS. An alpha 1-adrenoceptor agonist (phenylephrine) but not an alpha 2-adrenoceptor agonist (clonidine) mimicked Epi effects. Epi enhanced ROS production, which could be attenuated by the alpha- adrenoceptor blocker. Treatment of cells with H2O2 (100 µM) mimicked the effects of Epi on action potentials and a reactive oxygen species (ROS)-blocker (N-acetyl-I-cysteine, 1 mM) prevented the Epi effects, indicating that the ROS signalling is involved in the alpha-adrenoceptor actions. Nicotinamide adenine dinucleotide phosphate hydrogen (NADPH) oxidases were involved in alpha 1-adrenoceptor signalling. A protein kinase C (PKC) blocker suppressed the effects of Epi, phenylephrine and ROS as well, implying that PKC participated in alpha 1-adrenoceptor signalling and acted as a downstream factor of ROS. The abnormal action potentials resulted from alpha 1-adrenoceptor activation-induced dysfunctions of ion channels including the voltage-dependent Na+ and L-type Ca2+ channels.
Alpha 1-adrenoceptor signalling plays important roles for arrhythmogenesis of TTS. Alpha-adrenoceptor blockers might be clinically helpful for treating arrhythmias in patients with TTS.
本研究旨在探讨α-肾上腺素受体偶联信号在 Takotsubo 综合征（TTS）发病机制中的可能作用和潜在机制。
用人诱导多能干细胞衍生的心肌细胞（hiPSC-CMs）用肾上腺素（Epi，0.5 mM，1 小时）的毒性浓度处理，以模拟 TTS 的发生情况。采用膜片钳技术、聚合酶链反应（PCR）和荧光激活细胞分选（FACS）进行研究。高浓度的 Epi 抑制 hiPSC-CMs 的去极化速度，延长动作电位持续时间，并诱导心律失常事件。Epi 的作用被α-肾上腺素受体阻滞剂（苯肾上腺素）减弱，表明在 TTS 中 QT 间期延长的情况下，α-肾上腺素受体信号参与与心律失常发生相关的机制。α1-肾上腺素受体激动剂（苯福林）而不是α2-肾上腺素受体激动剂（可乐定）模拟了 Epi 的作用。Epi 增强了 ROS 的产生，这可以被α-肾上腺素受体阻滞剂减弱。用 H2O2（100 μM）处理细胞可模拟 Epi 对动作电位的作用，而 ROS 阻滞剂（N-乙酰-L-半胱氨酸，1 mM）可防止 Epi 的作用，表明 ROS 信号参与了α-肾上腺素受体的作用。烟酰胺腺嘌呤二核苷酸磷酸氢（NADPH）氧化酶参与α1-肾上腺素受体信号。蛋白激酶 C（PKC）阻滞剂抑制了 Epi、苯福林和 ROS 的作用，这表明 PKC 参与了α1-肾上腺素受体信号，并作为 ROS 的下游因子发挥作用。异常的动作电位是由α1-肾上腺素受体激活诱导的离子通道功能障碍引起的，包括电压依赖性 Na+和 L 型 Ca2+通道。
α1-肾上腺素受体信号在 TTS 的心律失常发生中起重要作用。α-肾上腺素受体阻滞剂可能对治疗 TTS 患者的心律失常有临床帮助。
