Materials

A total of 32 healthy canines of body weight 12±1.94 kg were selected for this study without gender restriction (Animal Experiment Center, Anhui Medical University).

Levosimendan (Qilu Pharmaceutical Co., Ltd., Ji Nan, China); malonaldehyde and superoxide dismutase reagent kits (Nanjing Jian Cheng Bioengineering Institute, Nan Jing, China); small animal ventilator (Chengdu Taimeng Science And Technology Co., Ltd., Cheng Du, China); -80℃ cryogenic refrigerator (Sanyo, Osaka, Japan); light microscope (CX40, Olympus, Tokyo, Japan); electron microscope (Hitachi, Tokyo, Japan); electronic balance (Sartorius, Gottingen, Germany); JHF1-DHG-9076A electrothermal constant temperature dry box (Beijng Tai’an Technology Services Ltd., Beijing, China); WI313182 blood-gas analyzer (East & West Analytical Instrument Co., Ltd., Beijing, China); cardiopulmonary bypass (Terumo Cardiovascular Systems Corporation, Ann Arbor, MI, USA); and CPBsupporting tubes; CPBcatheters and tracheal tubes.