昼夜节律对心力衰竭兔心肌细胞钙火花发生率及时空特性的影响

Influence of circadian rhythms in the incidence and spatiotemporal properties of calcium spark in myocardial cells in rabbits with heart failure

目的观察不同昼夜节律下心力衰竭兔心肌细胞自发性钙火花发生率、时空特性及对交感刺激的反应。方法家兔心衰模型采用主动脉返流加主动脉缩窄的方法制作,依据相隔12 h的昼夜节律将心衰动物分为静息组及活动组,并分别按时间点分离心肌细胞(每组24个细胞),使用激光共聚焦扫描技术制作细胞悬浊液并进行观察,测量钙火花发生率、幅值、半高宽、半高时程、上升时间和半衰减时间的变化。结果静息组心肌细胞自发性钙火花发生率及钙火花幅值、半高宽、半高时程、上升时间和半衰减时间明显低于活动组(P<0.05);给予ISO灌流后,静息组心肌细胞钙火花发生率及时空特性参数明显高于活动组(P<0.05)。结论昼夜节律可影响衰竭心肌细胞局部钙释放及交感反应性,其可能是夜间或静息状态下高发室性心律失常的机制之一。

Objective To observe the variation of the incidence and spatiotemporal properties of spontaneous calcium spark in myocardial cells of rabbits with heart failure and their response to β-Adrenergic stimulation with different circadian rhythms. Methods Rabbit models of heart failure were induced by combined aortic insufficiency and constriction, which were divided into resting group and active group according to circadian rhythms. Myocytes were isolated at 2 opposing time points （24 cells in each group）. Ceil suspension was prepared by confocal laser scanning and the observed. Incidence of calcium sparks and its spatiotemporal properties were evaluated by confocal scanning. Results Incidence rate, amplitude, full half-height width （FWDH）, full duration at half maximum （FDHM）, rising time （RT） and time to half-regression （THR） of spontaneous calcium spark in myocardial cells in resting group was markedly lower than that in active group （P〈0.05）. Under/3-Adrenergic stimulation, the incidence rate and properties of spontaneous calcium spark in myocardial cells in the resting group were significantly greater than that in the active group. Conclusion Circadian rhythms might influence the local calcium release and sympathetic reaction in failing heart cells, which could be a mechanism of high-incident venlricular arrhythmias at night or resting state.