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BACKGROUND: Revascularization is a successful therapeutic strategy for myocardial infarction. However, restoring coronary blood flow can lead to ischemia-reperfusion (I/R) injury. Low-dose 4-hydroxy-2-nonenal (HNE) therapy appears to play a key role in myocardial tolerance to I/R injury. We hypothesized that the positive effects of HNE on myocardial I/R injury may be UCP3-dependent.
MATERIAL AND METHODS: Adult male wild-type (WT) or UCP3 knockout (UCP3–/–) mice were pre-treated with the UCP inhibitor genipin or saline 1 h before ischemia and underwent 30-min coronary artery ligation followed by 24-h reperfusion. Mice were treated with intravenous HNE (4 mg/kg) or saline 5 min before reperfusion. Echocardiography was conducted to measure left ventricular end-diastolic posterior wall thickness (LVPWd), end-diastolic diameter (LVEDD), and fractional shortening (FS). Infarct size was measured by TTC staining. qRT-PCR and Western blotting were used to assess the expression of UCP3, UCP2, and the apoptosis markers cytochrome C and cleaved caspase-3.
RESULTS: HNE improved survival at 24 h post-MI in wild-type mice (p<0.05) but not in UCP3–/– mice. HNE preserved LVEDD and FS in WT mice (p<0.05) but not in UCP3–/– mice. HNE reduced infarct size in WT mice (p<0.05) but not in UCP3–/– mice. HNE upregulated UCP3 expression (p<0.05) but did not affect UCP2 expression. HNE reduced apoptosis marker expression in WT mice (p<0.05) but not in UCP3–/– mice. HNE’s positive effects were abrogated by genipin in an UCP3-dependent manner.
CONCLUSIONS: Low-dose HNE reperfusion therapy attenuates murine myocardial I/R injury in an UCP3-dependent manner. These effects are abrogated by genipin in an UCP3-dependent manner.

Keywords: Cardiovascular Diseases, Myocardial Infarction, Reperfusion Injury