The excised heart was placed in pre-warmed (37◦C) Dulbecco’s modified Eagle’s mediumF12 (DMEM/F12) supplemented with 10% FBS, 100 U/mL penicillin,100 g/mL streptomycin, 2 mM l-glutamine, 1 mM sodium pyruvate, and 0.1 mM Non-essential amino acids (Life technologies,USA).