Effect of Ischemic Preconditioning on Myocardial Oxygen Consumption During Ischemia

Ischemic preconditioning (IPC) in the heart may reduce myocardial energy demand. The present study was undertaken to examine changes in myocardial oxygen consumption (MVo2) during ischemia by IPC in Langendorff perfused rat hearts. We assessed MVo2during ischemia from the measurement of mitochondrial cyt. aa3redox state by a two-wavelength reflectance spectrophotometry where T1/2, the time from the onset of ischemia to the point for half reduction of cyt. aa3, was assumed to represent MVo2. The heart was preconditioned by three cycles of 5 min ischemia plus 5 min reperfusion and then subjected to 30 min global ischemia followed by reperfusion for 30 min. The T1/2was significantly longer in the preconditioned heart (30±6 s,n=10) than the control heart (14±5 s,n=9,P