High fat diet reduces the expression of miRNA‐29b in heart and increases susceptibility of myocardium to ischemia/reperfusion injury

Several studies have shown the role of microRNAs (miRNAs) in myocardial dysfunction in response to ischemia/reperfusion (I/R). In this study, we investigated the impact of high fat (HF) diet in the myocardial susceptibility to I/R injury, as well as in the expression of miRNA‐29b. Isolated heart experiments using the ex vivo Langendorff perfusion model were used to induce cardiac I/R injury. HF diet‐induced cardiac hypertrophy and impaired cardiac functional recovery after I/R. miRNA‐29b, which targets Col1, was reduced in the heart of HF diet‐fed mice, whereas the cardiac expression of Col1 was increased. In addition, hypoxia–reoxygenation (H/R) reduced the expression of miRNA‐29b in cardiomyoblasts cultures. However, the overexpression of miRNA‐29b in cardiomyoblasts reduced p53 mRNA levels and H/R injury, suggesting that downregulation of miRNA‐29b may be involved in I/R injury. Together, our findings suggest that the reduced expression of miRNA‐29b may be involved in the deteriorated cardiac functional recovery following I/R in obese mice. Obese mice displayed deteriorated cardiac functional recovery following the ischemia/reperfusion (I/R) injury, which was accompanied by the reduced expression of microRNA (miRNA)‐29b. Hypoxia–reoxygenation (H/R) reduced the expression of miRNA‐29b in cardiomyoblasts cultures. The overexpression of miRNA‐29b attenuated the increased cell death in response to H/R, suggesting that the reduced expression of miRNA‐29b may be involved in the deteriorated cardiac functional recovery following the I/R in obese mice.