Mtt solution

Cells were incubated with 0.25 mg/mL MTT solution (R&D Systems, Minneapolis, MN, USA) at 37°C for 3 h and the culture medium was removed, followed by the addition of dimethyl sulfoxide to produce blue formazan. Finally, absorbance at 630 nm was measured using a microplate reader (Mindray, Shenzhen, China).

The cultured H9C2 cells were seeded in 96-well culture plates, and after transfection and 1 μM ADR treatment, MTT solution (R&D Systems, Minneapolis, MN, USA) was added to each well. The cells continued to incubate for 4 hours in the incubator, then the supernatant of the 96-well plate was carefully discarded. 150 μL dimethyl sulfoxide (DMSO) (R&D Systems, Minneapolis, MN, USA) was added to each well and shaked for 10 minutes to fully melt the crystals. The activity of myocardial cells was detected, and the absorbance value of each well was measured by enzyme-linked immunoassay (Thermo Fisher Scientific, Waltham, MA, USA).