Figure 3).

Changes in ATP in the ischemic myocardium over time. ATP was significantly preserved in the preconditioning (PC) group until 25 min of sustained ischemia (P<0.05 versus control group). ATP preservation was attenuated in the PC plus N-2-mercaptopropionyl glycine (MPG) group (not signficant versus control or MPG group). No difference was observed at any time between the control and MPG groups. There were no significant differences in ATP among the four treatment groups after 30 min of sustained ischemia