目的 利用光遗传学技术是否能有效实施光照夺获心脏,实现心脏光起搏,探讨光照强度对心脏夺获率的影响.方法 取15只C57雌性小鼠,随机分成3组:正常组6只,空载病毒组6只,ChR2组3只(A、B、C小鼠),经颈静脉给三组小鼠分别注射100μl生理盐水,100μl pAOV-CAG-mcherry,100μlpAOV-CAG-hChR2(H134R)-mcherry.8周后,进行离体心脏Langendorff离体灌流,并给予473 nm的蓝光光照刺激,观察小鼠的心律是否能被光刺激夺获,并比较不同功率下的光刺激对心脏夺获率的影响,观察光刺激和电刺激产生的单相动作电位(MAP)之间是否存在差异.结果 ChR2组小鼠的心脏节律能被光照夺获,一定范围内夺获率与功率成正相关关系,且17.3 mW的光照基本能满足光照夺获心律所需功率的大小,正常组和空载病毒组小鼠心脏的节律均不能被光照夺获.ChR2组A、B、C3只小鼠光照夺获心律所需的功率大小差别较大,B小鼠心脏更容易被光夺获,可能与心脏ChR2表达量有关.光刺激与电刺激产生的MAP存在差异,光刺激产生的MAP的达峰时间比电刺激短,且动作电位的复极时程达10％,30％,50％,70％的值小于电刺激.结论 利用光遗传学技术实现心脏光起搏技术可行.光敏蛋白ChR2成功表达在靶器官上是光遗传学关键的一步,光刺激心脏的夺获率不仅与光照功率的大小有关,可能还与心脏表达ChR2的量相关.%Objective To investigate the possibility of capturing the rhythms of heart and achieving optical pacing by optogenetics and compare the effectiveness of illumination with different parameters.Method Fifteen C57 mice were randomly divided into three groups,the normal group (n =6),the no-load virus group (n =6),and the ChR2 group (n=3;A,B,C mice).Three groups of mice were separately injected 100 μl normal saline,100 μl pAOV-CAG-mcherry and 100 μl pAOV-CAG-hChR2(H134R)-mcherry into jugular vein.After eight weeks,the isolated heart was stimulated by 430nm blue light with different illumination intensities closed to the surface of heart in Langendorff apparatus.We observed whether the rhythm of heart can be captured by light stimulation with different illumination power and compare the difference of monophasic action potential(MAP) induced by light stimula tion and electric stimulation.Result The rhythm of the heart expressing ChR2 was easier to be controlled by the blue light pulse with higher power,and the light with the power of 17.3 mW was sufficient to pacing the heart.However the normal group and the no-load virus group cannot be captured by light.The result showed that the illumination power required for optogenetics pacing of the heart was obviously dissimilar,and B was easier to be paced which may related to the expression of ChR2.The record of MAP showed that the time to peak and the action potential duration APD 10,30,50,70 produced by light pulse was shorter than electric stimulation.Conclusion Optical pacing of the heart by optogenetics is feasible,and it is associated with not only illumination power but also the expression of light-sensitive protein.
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