Optogenetic manipulation of cardiac electrical dynamics using sub-threshold illumination: dissecting the role of cardiac alternans in terminating rapid rhythms

作者：Valentina Biasci, Lorenzo Santini, Gerard A. Marchal, Sayedeh Hussaini, Cecilia Ferrantini, Raffaele Coppini, Leslie M. Loew, Stefan Luther, Marina Campione, Corrado Poggesi, Francesco S. Pavone, Elisabetta Cerbai, Gil Bub, Leonardo Sacconi · 发表于：Basic Research in Cardiology · 年份：2022 · DOI：10.1007/s00395-022-00933-8 · 被引用次数：33 · 研究领域：Photoreceptor and optogenetics research、Photosynthetic Processes and Mechanisms、Neural dynamics and brain function

cycling. Experimental methods for manipulating AP electrical dynamics commonly use ion channel inhibitors that lack spatial and temporal specificity. In this work, we propose an approach based on optogenetics to manipulate cardiac electrical activity employing a light-modulated depolarizing current with intensities that are too low to elicit APs (sub-threshold illumination), but are sufficient to fine-tune AP electrical dynamics. We investigated the effects of sub-threshold illumination in isolated cardiomyocytes and whole hearts by using transgenic mice constitutively expressing a light-gated ion channel (channelrhodopsin-2, ChR2). We find that ChR2-mediated depolarizing current prolongs APs and reduces conduction velocity (CV) in a space-selective and reversible manner. Sub-threshold manipulation also affects the dynamics of cardiac electrical activity, increasing the magnitude of cardiac alternans. We used an optical system that uses real-time feedback control to generate re-entrant circuits with user-defined cycle lengths to explore the role of cardiac alternans in spontaneous termination of ventricular tachycardias (VTs). We demonstrate that VT stability significantly decreases during sub-threshold illumination primarily due to an increase in the amplitude of electrical oscillations, which implies that cardiac alternans may be beneficial in the context of self-termination of VT.