Objective:To explore the alterations of the calcium transient in the development of heart failure,and the impact of levosimendan(LeV)on intracellular Ca2+ dynamics. Methods:The neonatal rat ventricular myocytes in culture were divided into 4 groups,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 Ca2+ 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 Ca2+(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 Ca2+ transient amplitude and resting Ca2+.(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 Ca2+,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 Ca2+ release in failing rat ventricular myocyte. Levosimendan exerts positive inotropic effect through accelerating the velocity of calcium signaling propagation and synchronzing the calcium release.