Institute of Biological and Medical Engineering, Pontificia Universidad Católica de Chile, Santiago, Chile.
FONDAP Center for Genome Regulation, Facultad de Ciencias, Universidad de Chile, Santiago, Chile.
Zebrafish. 2019 Oct;16(5):427-433. doi: 10.1089/zeb.2019.1753. Epub 2019 Jun 27.
The study of myocardial transmembrane ion currents is fundamental to understand frequent pathologies such as arrhythmias and ischemia. Conventional electrocardiography (ECG) is not able to record ion currents, while the use of intracellular microelectrodes in a beating heart has technical limitations. Myocardial monophasic action potentials (MAPs) recorded with suction electrodes allow the evaluation of ionic currents similar to those recorded by intracellular glass microelectrodes. The technique is based on the fact that suction, through a small diameter tube, on the myocardial cell, induces an opening at the membrane, connecting the intracellular media to the electrode by a saline bridge. The electrophysiology of zebrafish heart is remarkably similar to the human; however, evaluation of MAPs has not been yet explored. In this study, we aimed to establish a myocardial MAP recording technique for adult zebrafish. Male adult wild-type zebrafish were anesthetized and 50% of the beating ventricle was exposed. A glass hematocrit capillary tube (1.1 mm inner diameter) was used as a suction electrode connected to a 3-way stopcock valve, which is also connected to a syringe containing a chloride-coated silver wire for signal recording. Gentle suction was exerted by a syringe filled with ringer and connected to the 3-way stopcock valve. Two needles were used for ground (tail) and indifferent (abdomen) electrodes. Without suction, the system can record conventional ECG, but applying suction MAPs are registered and show typical morphology with phase 0-4 sequence. MAP amplitude and duration values show low variability. Ischemia and/or lidocaine-induced Na channel blocking dramatically reduced MAP amplitude. These results strongly suggest that the suction electrode technique is a promising method to record myocardial ion currents in zebrafish.
研究心肌跨膜离子电流对于理解心律失常和缺血等常见病理非常重要。传统的心电图（ECG）无法记录离子电流，而在跳动的心脏中使用细胞内微电极则存在技术限制。用吸液电极记录的心肌单相动作电位（MAP）允许评估与细胞内玻璃微电极记录的相似的离子电流。该技术基于以下事实：通过小管对心肌细胞进行抽吸会在膜上诱导开口，通过盐桥将细胞内介质连接到电极。斑马鱼心脏的电生理学与人类非常相似；然而，MAP 的评估尚未得到探索。在这项研究中，我们旨在为成年斑马鱼建立心肌 MAP 记录技术。雄性成年野生型斑马鱼被麻醉，50%的跳动心室暴露在外。使用玻璃血细胞比容毛细管（内径 1.1 毫米）作为吸液电极，连接到三通阀，三通阀还连接到含有氯化银线的注射器，用于信号记录。用充满林格氏液的注射器施加轻微的吸力，连接到三通阀。两根针用于接地（尾巴）和无关电极（腹部）。在不抽吸的情况下，该系统可以记录常规 ECG，但施加抽吸后会记录到 MAP，并显示出具有 0-4 相序列的典型形态。MAP 幅度和持续时间值的变化很小。缺血和/或利多卡因诱导的钠通道阻断显著降低了 MAP 幅度。这些结果强烈表明，吸液电极技术是记录斑马鱼心肌离子电流的一种很有前途的方法。
