Effects of iron overload, an iron chelator and a T-Type calcium channel blocker on cardiac mitochondrial biogenesis and mitochondrial dynamics in thalassemic mice
Although cardiac mitochondrial dysfunction is involved in the pathophysiology of iron-overload cardiomyopathy, the precise mechanisms of iron-induced mitochondrial dysfunction, and the roles of the iron chelator deferiprone and the T-type calcium channel blocker efonidipine on cardiac mitochondrial biogenesis in thalassemic mice are still unknown. β-thalassemic (HT) mice were fed with a normal diet (ND) or a high iron-diet (FE) for 90 days. Then, the FE-fed mice were treated with deferiprone (75 mg/kg/day) or efonidipine (4 mg/kg/day) for 30 days. The hearts were used to determine cardiac mitochondrial function, biogenesis, mitochondrial dynamics and protein expressions for oxidative phosphorylation (OXPHOS) and apoptosis. ND-fed HT mice had impaired heart rate variability (HRV), increased mitochondrial dynamic proteins and caspase-3, compared with ND-fed wild-type mice. Iron overload led to increased plasma non-transferrin bound iron, oxidative stress, and the impairments of HRV and left ventricular function, cardiac mitochondrial function and mitochondrial dynamics, and decreased complex IV in thalassemic mice. Our results suggested that deferiprone and efonidipine treatment showed similar benefit in attenuating cardiac iron deposit and oxidative stress, and improved cardiac mitochondrial function, leading to improved left ventricular function, without altering the cardiac mitochondrial biogenesis, and apoptosis proteins in iron-overload thalassemic mice.