Dynamin‐related protein 1 (Drp1)‐mediated diastolic dysfunction in myocardial ischemia‐reperfusion injury: therapeutic benefits of Drp1 inhibition to reduce mitochondrial fission

Mitochondrial fission, regulated by dynamin‐related protein‐1 (Drp1), is a newly recognized determinant of mitochondrial function, but its contribution to left ventricular (LV) impairment following ischemia‐reperfusion (IR) injury is unknown. We report that Drp1 activation during IR results in LV dysfunction and that Drp1 inhibition is beneficial. In both isolated neonatal murine cardiomyocytes and adult rat hearts (Langendorff preparation) mitochondrial fragmentation and swelling occurred within 30 min of IR Drp1‐S637 (serine 637) dephosphorylation resulted in Drp1 mitochondrial translocation and increased mitochondrial fission. The Drp1 inhibitor Mdivi‐1 preserved mitochondrial morphology, reduced cytosolic calcium, and prevented cell death. Drp1 siRNA similarly preserved mitochondrial morphology. In Langendorff hearts, Mdivi‐1 reduced mitochondrial reactive oxygen species, improved LV developed pressure (92±5 vs. 28±10 mmHg, P