HMOX1 and ischemia: During cardiac ischemia-reperfusion injury, ROS generation can increase the expression of HO-1 [23], consistent with the results obtained in this study, and the expression of endogenous HO-1 increases with the duration of reoxygenation and reaches maximum levels after 2 hours of H/R; thereafter, the expression gradually decreases to a stable level over time (Fig 1B and 1C).