A cholesterol-rich diet improves resistance to ischemic insult in mouse hearts but suppresses the beneficial effect of post-conditioning.

Background Conflicting evidence is reported about the beneficial effects of post-conditioning (Post-C) in pathologic conditions. A pathologic mouse model of hypercholesterolemia was used. The study examined the effect of Post-Con cardiac recovery after the ischemia-reperfusion sequence and the effect of Post-Con on low-density lipoprotein receptor-deficient (LDLR −/− ) mice and control animals. Methods LDLR −/− and C57bl/6 mice were fed for 8 weeks with a high-cholesterol (1.25%) or normal diet. The hearts were isolated and perfused on a working heart apparatus. The hearts underwent 20 minutes of global total ischemia, followed by 36 minutes of reperfusion. Post-Con was applied at the onset of reperfusion with three 10-second cycles of ischemia-reperfusion. Tissue injury was evaluated (triphenyl-tetrazolium chloride staining), and superoxide anion production was assessed (dihydroethidium). Results Post-ischemia recovery was very low in the control and LDLR −/− groups, and Post-C induced an increase in functional recovery ( p −/− and C57bl/6 ( p Conclusions Our results demonstrated that control and LDLR −/− mice may be protected by Post-C, and an 8-week high-cholesterol diet led to improved recovery of the myocardium after the ischemia-reperfusion sequence in both series. However, the endogenous protective mechanism of Post-C appears to be lost in the presence of hypercholesterolemia.