This study aimed to explore the changes in calcium transient in the development of heart failure and the effects of levosimendan (LeV) on intracellular calcium dynamics. Cultured neonatal rat ventricular myocytes were divided into four groups: normal, norepinephrine (NE) only (10 µmol/L), NE + LeV1 (0.1 µmol/L), and NE + LeV2 (1 µmol/L). The calcium transients of the myocytes loaded with Fluo-3/AM were observed using a laser scanning confocal microscope. Compared with the control group, the calcium wave in the NE group dispersed, propagated slowly, and exhibited dyssynchrony of Ca 2+ release. Norepinephrine accelerated the beating rate of the cultured myocytes, decreased the systolic peak Ca 2+ , and increased the time to peak (Ttp) and decay time (Tau) of calcium transient. Levosimendan increased the synchrony of calcium transient, and reduced Ttp and Tau. In contrast, LeV did not affect the beating rate and systolic peak Ca 2+ . Both NE-only- and LeV-treated groups did not affect re...