Abstract

A number of systemic heart diseases leading to the development of heart failure (aortic stenosis, hypertension, diabetic cardiomyopathy, reperfusion injury etc.) are accompanied by a pronounced reorganization of the T-system of cardiomyocytes, both in humans and animals. However, structural-functional changes within this membrane compartment of cardiomyocytes following ischemia-reperfusion (IR) have not been thoroughly studied. The aim of the work was to study the remodeling of the T-system in the subepicardial cardiomyocytes of the left ventricle (LV) of the rat heart after IR injury using confocal microscopy and extracellular recording methods. The study was carried out after 24 hours, two weeks, and four weeks following IR. A remodeling of extracellular action potentials, recorded in the cardiomyocyte membrane patches that are devoid of t-tubule entrances (a single negative peak, type 1 eAP), was observed. Starting from 24 hours up to 4 weeks after IR, there was an increase in the duration of their decline time (T ₉₀) and the formation of eAP after-hyperpolarization phase, reaching maximum values by the fourth week after IR. A decrease in the amplitude of the second peak of eAPs, recorded in the cardiomyocyte membrane patches that contained t-tubule openings (a double negative peak, type 2 eAP), was also noticed four weeks after IR. However, in this investigation, no observable changes in the structural organization of the T-system were found. These data suggest that functional modifications of the epicardial cardiomyocyte T-system after IR injury may precede its structural modifications.

中文翻译：

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大鼠心脏缺血再灌注损伤后心外膜下心肌细胞细胞外记录动作电位的重塑

摘要

在人类和动物中，许多导致心力衰竭发展的系统性心脏病（主动脉瓣狭窄、高血压、糖尿病心肌病、再灌注损伤等）都伴随着心肌细胞T系统的显着重组。然而，缺血再灌注（IR）后心肌细胞膜区室的结构功能变化尚未得到彻底研究。这项工作的目的是使用共聚焦显微镜和细胞外记录方法研究 IR 损伤后大鼠心脏左心室 (LV) 心外膜下心肌细胞 T 系统的重塑。该研究在 IR 后 24 小时、两周和四周后进行。观察到细胞外动作电位的重塑，记录在没有 T 管入口的心肌细胞膜斑块中（单个负峰，1 型 eAP）。从IR后24小时开始直至4周，它们的下降时间( T ₉₀ )持续时间增加，并且eAP超极化后阶段的形成增加，在IR后第四周达到最大值。IR 后 4 周，还注意到在包含 t 管开口的心肌细胞膜斑块中记录的 eAP 第二个峰振幅下降（双负峰，2 型 eAP）。然而，在本次调查中，没有发现 T 系统的结构组织发生明显变化。这些数据表明，IR损伤后心外膜心肌细胞T系统的功能改变可能先于其结构改变。