左西孟旦对去甲肾上腺素诱导的心肌细胞钙瞬变信号的影响

Effects of levosimendan on calcium transient in norepinephrine-cultured neonatal rat ventricular myocytes

目的 :研究心肌细胞衰竭过程中钙瞬变信号的变化及左西孟旦(levosimendan,LeV)对其影响。方法 :培养Sprague Dawley(SD)乳大鼠心肌细胞48 h后,分为对照组、去甲肾上腺素(NE)组、NE+LeV1(0.1μmol/L)诱导组和NE+LeV2(1μmol/L)诱导组。NE组以去甲肾上腺素10μmmol/L诱导;NE+LeV1组先用NE诱导,再以LeV 0.1μmol/L干预;NE+LeV2组先用NE诱导,再以LeV 1μmol/L干预。用Ca^(2+)荧光指示剂Fluo-3/AM负载心肌细胞,激光共聚焦显微镜观察心肌细胞钙瞬变信号变化以及心肌细胞的搏动频率。结果:1与对照组相比,NE组心室肌细胞钙波分散、传导减慢、同步性较差,细胞搏动频率较快(26.7±4.3 vs.11.6±3.6,P<0.01)、收缩期钙瞬变峰值下降(128.37±65.44 vs.155.33±61.77,P<0.05)、达峰时间(Ttp,0.413±0.324 vs.0.212±0.050,P<0.01)、衰减时间(Tau,1.162±0.524 vs.0.722±0.169,P<0.01)均延长,钙瞬变幅度(60.80±39.88vs.75.41±36.52,P>0.05)、谷值(67.57±42.59 vs.79.92±38.05,P>0.05)变化不大;2 LeV处理后,钙波传导均匀同步,心肌细胞搏动频率及钙瞬变的峰值、幅度、谷值较NE组无明显变化,NE+LeV1组和NE+LeV2组Ttp分别为(0.212±0.044、0.205±0.062)、Tau分别为(0.735±0.269、0.753±0.152)均较NE组缩短(P<0.01);3NE+LeV1与NE+LeV2两组相比,钙瞬变峰值和谷值、钙瞬变幅度、Ttp和Tau差别无统计学意义。结论:心肌细胞衰竭过程中钙瞬变减弱变慢、同步性较差;LeV通过增加钙瞬变速度、改善钙瞬变传导形式,发挥正性肌力作用。

Objective：To explore the alterations of the cal cium transient in the development of heart failure,and the impact of levosimendan（LeV）on intracellular Ca^（2＋） dynamics. Methods：The neonatal rat ventricular myocytes in culture were divided into 4groups,normal,NE alone（10 μmol / L）,NE＋LeV1（0.1 μmmol / L）, and NE＋LeV2（1 μmmol / L）. Calcium transients of myocytes loaded by Fluo-3 / AM were observed under Laser scanning confocal microscope. Results：（1）Compared with the control,calcium wave dispersed,conducted slowly,and exibited dyssynchrony of Ca^（2＋）release in NE group,NE accelerated the cultured cell beating rate（26.7 ± 4.3 vs. 11.6 ± 3.6,P〈0.01）,decreased peak systolic Ca^（2＋）（128.37 ± 65.44 vs. 155.33 ± 61.77,P〈0.05）,shortened time to peak（Ttp;0.413 ± 0.324 vs. 0.212 ± 0.050,P〈0.01）and decay time（Tau;1.162 ± 0.524 vs. 0.722 ± 0.169,P〈0.01）of calcium transient,except Ca^（2＋） transient amplitude and resting Ca^（2＋）.（2）NE in the presence of LeV increased synchrony of calcium transient,reduced Ttp（0.212 ± 0.044 vs. 0.413 ± 0.324,NE＋LeV1 vs. NE,P〈0.01 and 0.205 ± 0.062 vs. 0.413 ± 0.324,NE ＋LeV2 vs. NE,P〈0.01 respectively）and Tau（0.735 ± 0.269 vs. 1.162 ± 0.524,NE ＋LeV1 vs. NE,P〈0.01; and 0.753 ± 0.152 vs. 1.162 ± 0.524,NE＋ LeV2 vs. NE,P〈0.01）,had no effect on cell beating rate,peak systolic or resting Ca^（2＋）,and transient amplitude.（3）There were no concentration difference in the presence of Levosimendan. Conclusion：Our results show that calcium transient gets weaker and slower,exibiting dyssynchrony of Ca^（2＋）release in failing rat ventricular myocyte. Levosimendan exerts positive inotropic effect through accelerating the velocity of calcium signaling propagation and synchronzing the calcium release.