Figure 1. Schematic representation of experimental protocol. Starting time of infusion with Krebs-Henseleit bicarbonate (KHB) buffer, Intralipid, or propofol was taken as 0 min. The effects of propofol on the mechanical function and energy metabolism were investigated in the H²O²-treated and normal heart experiments. In the H²O²-treated heart experiments, each of the Krebs-Henseleit bicarbonate, Intralipid, 25-micro Meter propofol, and 50-micro Meter propofol groups was divided into two subgroups; in the first subgroup the infusion was continued for 40 min, and in the second subgroup it was continued for 25 min. In the normal heart experiments, each of the Krebs-Henseleit bicarbonate, Intralipid, 25-micro Meter propofol, and 50-micro Meter propofol groups was divided into three subgroups; in the first, second, and third subgroups the infusion was continued for 40, 25, and 10 min, respectively. In the 50-micro Meter propofol/Intralipid group in both H sub 2 O²-treated and normal heart experiments, propofol was infused for 30 min and then Intralipid was infused for 10 min. H²O²(600 micro Meter as a final concentration in perfusate) or distilled deionized water (DDW) was infused from 10 min after to 14 min after the start of infusion with Krebs-Henseleit bicarbonate buffer, Intralipid, or propofol; H²O²was infused for 4 min. All the hearts were frozen (F) for measurements of energy metabolites or malondialdehyde at the end of each infusion with Krebs-Henseleit bicarbonate buffer, Intralipid, or propofol.