Establishment of the Isolated Rat Heart Ischemia–Reperfusion Model

Animal anesthesia was induced via an intraperitoneal injection of sodium pentobarbital (30 mg/kg) (22). The rat heart was isolated from the thoracic cavity, hung on a Langendorff perfusion device from the root of the aorta, and perfused with O₂-saturated Krebs–Henseleit (K-H) solution (127 mmol/L of NaCl, 17.7 mmol/L of NaHCO₃, 5.1 mmol/L of KCl, 1.5 mmol/L of CaCl₂, 1.26 mmol/L of MgCl₂, and 11 mmol/L of d-glucose, pH = 7.4) at a constant pressure of 75 mmHg and in a constant temperature (37°C), as described previously (22). Myocardial IR was induced by stopping K-H solution perfusion for a period of 30 min, followed by reperfusion with K-H solution for 90 min. The fluid-filled latex balloon, which was connected to a pressure sensor, was inserted into the left ventricle to dynamically monitor the alteration of cardiac function using a homodynamic system (MP150; BIOPAC Systems, Inc.; Goleta, CA, USA).