OPA1 and myocardial infarction: Nevertheless, the downregulation of OPA1 by siRNA transfection surprisingly abrogates the protective effects of calpain suppression on mitochondrial fission/fusion and mitophagy, indicating that MCU repression restrains calpain/OPA1-mediated mitochondrial fusion/mitophagy inhibition to shrink the myocardial infarction size and reduce levels of apoptosis (64).