Reduced Aerobic Metabolic Efficiency in Postischemic Myocardium Dysfunction in Rats: Role of Aging

It has been suggested that aging may enhance the deleterious effects of myocardial ischemia-reperfusion. This study evaluates the relationship between oxygen consumption and functional impairment during reperfusion following myocardial ischemia in adult and senescent rat hearts. Global ischemia induced a marked impairment of contractile function which was significantly higher in senescent than in adult hearts. During reperfusion postischemic dysfunction was more evident in senescent hearts: at the 10th minute, the developed pressure recovered less (p < 0.05) and end-diastolic pressure increased more (p < 0.05) in senescent than in adult hearts. However, oxygen consumption per unit of work was significantly higher throughout 60 min of reperfusion when compared to controls with no significant difference between adult and senescent hearts. This study demonstrates that following ischemia and reperfusion depression of function and inappropriately high oxygen consumption were observed in both adult and senescent hearts. However, aging was associated with greater contractile impairment, which occurred in the absence of further deterioration of metabolic efficiency of contraction.