可见光起搏心脏的在体实验研究

Research of pacing heart by visible light in vivo

目的探究473 nm可见蓝光能否对表达光敏感蛋白channelrhodopsin-2 (ChR2)的大鼠心脏成功实现在体光起搏及光起搏所需的光照功率密度与脉冲波宽的关系。方法将27只SD大鼠随机分为三组:正常组、ChR2组、空载病毒组,每组9只。分别经右侧颈静脉注射60μl PBS,60μl载有ChR2的腺相关病毒[AAV9-CAG-hChR2 (H134R)-mCherry],60μl空载病毒(AAV9-CAG-mCherry)。8周后,大鼠经麻醉开胸充分暴露心脏后,给予473 nm蓝光8 Hz频率的脉冲照射心脏右心室,并同步记录光照输出信号和体表心电图,改变光照功率密度(0.03～1.97 mw/mm^2)和脉冲波宽(2、5、10、20、50 ms),观察光照对心室夺获起搏的情况。结果 8 Hz脉冲光照固定脉冲宽度20 ms时,0.64 mw/mm^2可完全夺获心脏节律。在0.03～0.64 mw/mm^2范围内,心脏夺获率随功率密度增大而增加,夺获率可达100%。改变473 nm蓝光脉冲波宽,完全起搏心脏所需最小光照功率密度(mw/mm^2)依次为0.46±0.33, 0.26±0.10, 0.18±0.04,0.13±0.04,0.16±0.07。2倍功率密度阈值脉冲光照结束后,心电图RR间期、QT间期、QRS波宽与基础心率无显著差异(P均>0.05)。结论颈静脉注射腺相关病毒AAV9-CAG-hChR2 (H134R)-mCherry能够使心脏表达光敏感蛋白ChR2,473 nm蓝光可有效起搏心脏。心脏夺获率与光照的功率密度和脉冲宽度有关。

Objective To investigate whether 473 nm blue light can achieve pacing the heart of SD rats in vivo successfully which expressed the light-sensitive protein ChR2 and the relationship between the light intensity and the light pulse duration required for optical pacing. Methods Twenty-seven SD rats were randomly divided into three groups: normal group, ChR2 group and non-ChR2 group, 9 rats in each group. Systemic delivery via right jugular vein injection of 60 μl of normal saline, adeno-associated virus [AAV9-CAG-hChR2(H134 R)-mCherry] carrying the gene of the light-sensitive ion channel protein channelrhodopsin-2(ChR2), and non-ChR2 virus(AAV9-CAG-mCherry) into three groups of rats separately. After 8 weeks, 473 nm blue light was performed in open-chest anesthetized rats in vivo. The right ventricle of the heart was irradiated with 473 nm blue light and change the illumination parameters: the light intensity(0.03-1.97 mw/mm^2) and pulse duration(2,5,10,20,50 ms). The output signal of light and the surface electrocardiogram(ECG) of rats was recorded simultaneously. Results Blue light(8 Hz 20 ms 0.64 mw/mm2)on the right ventricle of SD rats completely captured the heart rhythm. The greater the light intensity in the range of 0.03-0.64 mw/mm^2, the greater the cardiac capture rate until 100%. 8 Hz 473 nm blue light completely capturing the heart rhythm with different pulse duration, the minimum illumination intensity(mw/mm^2) required for the heart successively is(0.46 ± 0.33),(0.26 ± 0.10),(0.18 ± 0.04),(0.13 ± 0.04),(0.16 ± 0.07) mw/mm^2. Moreover, there was no significant difference between the RR, QRS and QT interval of the ECG before and after pulse illumination of two times intensity threshold(P>0.05, respectively). Conclusions The jugular vein injection of adeno-associated virus AAV9-CAG-hChR2(H134 R)-mCherry can delivery enough light-sensitive protein ChR2 expressed in SD rats and 473 nm blue light ensure cardiac pacing effectively. The capture rate is related to the light intensity and pulse duration.[Chinese Journal of Cardiac Pacing and Electrophysiology,2019,33(2):133-137]