The mice received a separate minipump for co-infusion of MitoTEMPO or saline. The mice were anesthetized by pentobarbital (50 mg per body, intraperitoneally) and an osmotic minipump (ALZET micro-osmotic pump, model 1002; DURECT Co., Cupertino, California, USA) was subcutaneously implanted. MitoTEMPO (180 µg/kg/day) and saline as a control for the old mice and saline for the young mice were infused continuously. Blood pressure was monitored using the tail-cuff method. Previously, we measured the systolic blood pressure and heart rate in mice administered MitoTEMPO (50, 180, and 500 µg/kg/day) with an osmotic minipump at 14 days after infusion. When treated with 500 µg/kg/day of MitoTEMPO, systolic blood pressure decreased over 5% (P<0.05) compared with before treatment, which are identical to the results of a previous report 7 (link). Left ventricular diastolic function (E/e′) and heart rate did not change with or without administration of 50 µg/kg/day of MitoTEMPO; that is, the effect of MitoTEMPO is doubtful as the dose is too small. Therefore, we considered the suitable dose of MitoTEMPO to be 180 µg/kg/day. Twenty-eight days after surgery, the animals were killed with a lethal dose of pentobarbital and examinations of the coronary artery, cardiac myocytes, and aorta were performed.