利用光遗传学技术构建小鼠光控心脏起搏模型

A Mouse Model of Light-Controlled Cardiac Pacing

电刺激是人工控制心脏搏动频率的标准技术,但在实验研究中,这种方法有较大的局限性,如局部电解效应、刺激频率和时长受限、只能对目标范围内的所有细胞进行刺激、不能选择性作用于心肌细胞等。基于光遗传学技术,本研究构建了心肌细胞特异性表达光激活阳离子通道channelrhodopsin-2(ChR2)的转基因小鼠,采用特定频率的蓝光刺激使心肌细胞膜电位去极化,从而引发动作电位并控制心脏起搏。当蓝光刺激频率低于小鼠自发心脏搏动频率时,蓝光刺激造成暂时性的心律失常,去除蓝光照射后小鼠心跳恢复正常;当蓝光刺激频率高于小鼠自发心跳频率时,小鼠的心脏搏动完全由蓝光刺激支配,去除蓝光照射后恢复到自发搏动状态;失去自主搏动能力的小鼠心脏也可由蓝光刺激进行起搏;不表达ChR2的对照小鼠对蓝光刺激没有响应。本研究对基于光遗传学的光控心脏起搏技术进行了实验论证,在心肌电生理学特别是心律失常研究中有着非常重要的应用价值。

Electrical stimulation is a standard technique for controlling cardiac beating frequency. However, in experimental studies, this method has critical technical limitations, such as local electrolysis effect, limited stimulation frequency and duration, stimulating all cells within the target range, and lack of selectivity on cardiomyocytes. Based on optogenetic technology, transgenic mice with specific expression of photoactivated cationic channel channelrhodopsin-2 (ChR2) in cardiomyocytes were constructed, and then blue light at specific frequency was used to stimulate cardiomyocytes and depolarize the membrane potential which can trigger the action potential and control the cardiac pacing. When the frequency of blue-light stimulation was lower than the spontaneous heart-beating frequency of mice, the blue-light stimulation caused temporary cardiac arrhythmia, while the heart beating of mice returned to normal after the removal of blue-light illumination. When the frequency of blue-light stimulation was higher than the spontaneous heart rate of the mice, the heart beats of mice were completely controlled by blue-light stimulation, and returned to the spontaneous beating state after removing the blue light. Moreover, mouse hearts failed to beat autonomously could also be paced by blue light, and ChR2-deficient mice showed no response to blue-light stimulation. Therefore, optogenetics-based light-controlled cardiac-pacing technique is experimentally demonstrated in this study, which has very important values in cardiac electrophysiology, especially in the study of arrhythmias.