Effects of aging on the changes in ATP hydrolysis after ischemia-reperfusion in the coronary circulation . Control perfusion and ischemia-reperfusion were performed as indicated in Figure 2 in young adult and aged rats. A substrate of eATP (10 μM, 0.3 ml) was administrated into the coronary perfusate and subsequent metabolites in the effluent were measured by HPLC. Data are shown as percent of total metabolites collected from control hearts (A) and ischemia-reperfusion hearts (B). Gray columns: young adult rats , black columns: aged rats. All values are means ± S.E.M (n = 5). *P < 0.05 , **P < 0.01 significantly different from the control value by Student’s t-test.