Fig. 2.

Repletion of NAD⁺ dose-dependently attenuates contractile dysfunction in HL-1 cardiomyocytes and Drosophila. a, b Representative CaT traces and quantified CaT amplitude data of control non-paced (NP) and tachypaced (TP) HL-1 cardiomyocytes pretreated with or without different doses of NAD⁺ (0.25, 0.5, 1 mM). ^**P < 0.01 vs. Control (CTL) NP ^##P < 0.01 vs. CTL TP, n = 40 cardiomyocytes CTL NP, n = 40 for CTL TP, n = 20 for NAD⁺ (0.25 mM) TP, n = 40 for NAD⁺ (0.5 mM) TP, and n = 20 for NAD⁺ (1 mM) TP. c Representative heart wall motions (during 3.3 s). d, e Quantified data of relative heart rate and arrhythmicity index to control NP Drosophila. Drosophila were treated with or without NAD⁺ (5 or 10 mM). ^*P < 0.05, ^**P < 0.01 vs. CTL NP ^##P < 0.01 vs. CTL TP. n = 10 Drosophila prepupae for CTL NP, n = 8 for CTL TP, n = 6 for NAD⁺ (5 mM) TP, n = 7 for NAD⁺ (10 mM). Data are all expressed as mean ± s.e.m. Individual group mean differences were evaluated with the two-tailed Student’s t test