Fig. 1

Mild ischemic-reperfusion (mI-R) heart preparation. a Coronary gradual and partial occlusion was performed in 10 s by ligation of proximal left anterior descending artery and attached 1-mm-diameter soft tube (as buffer) using a bulldog clamp at the knot of 4-0 polypropylene suture under monitoring LV pressure–volume (P–V) loop. b Typical left ventricular (LV) pressure–volume loops during gradual and partial coronary occlusion to make mild ischemic-reperfusion heart preparations. c A typical macrograph of the preparation of time control. d A typical LV macrograph of the mI-R preparation obtained 20 min after mI-R. No myocardial infarction was observed. e A typical macrograph of the preparation of acute myocardial infarction (MI) obtained 20 min after severe I-R. The infarct tissue was indicated by the white dotted boundary. It appeared white even by naked eyes. The non-injured tissue was indicated by an arrow outside the infarct tissue