BACKGROUND: The interaction between ischemic preconditioning (IPC) and propofol-induced cardioprotective effects during prolonged cold ischemia has not been studied yet. The purpose of this study is to investigate the effects of ischemic preconditioning and propofol on cardiac function and the development of endothelial injury after 4 hours of cold cardioplegia and reperfusion.

METHODS: After suspension of the isolated heart on the Langendorff perfusion system, we took a stabilizing period for 15 minutes, perfusion period for 15 minutes, global cold (4oC) ischemic period for 4 hours, and then reperfusion period for 60 minutes. There were 4 groups: (1) CONTROL group, no intervention; (2) IPC group, two 2-minute total coronary occlusions interspaced with 5 minutes of normal reperfusion; (3) PROPOFOL group, propofol (2micrometer) was infused during reperfusion period; (4) BOTH group, ischemic preconditioning and postischemic propofol treatment group. The measurements of cardiac performances, such as left ventricular developed pressure (LVDP), rate of ventricular pressure generation (dp/dt), and heart rate (HR) was obtained at pre- and postischemic periods. For the evaluation of endothelial injury during reperfusion period, coronary flow responses to bradykinin were tested. Infarct size was measured using the triphenyl tetrazolium stain.

RESULTS: IPC, PROPOFOL, and BOTH groups showed better outcome of LVDP, dp/dt, HR, and flow responses to bradykinin than CONTROL group did. But there is no statistically significant difference in variables among the three groups.

CONCLUSIONS: Ischemic preconditioning and postischemic propofol have cardioprotective effect respectively but no additive effect after 4 hours cold cardioplegia and reperfusion.