The Calcium Uniporter Regulates The Permeability Transition Pore In Isolated Cortical Mitochondria

Objective To determine whether the mitochondrial calcium uniporter plays a role on the mitochondrial permeability transition pore in isolated rat brain mitochondria.Methods Mitochondria were isolated from adult male Wistar rats according to a standard differential centrifugation procedure. Ultrastructural examination of isolated mitochondrial preparations was performed using transmission electron microscopy. Mitochondrial permeability transition pore opening was determined by mitochondrial swelling. Isolated mitochondria were treated with mitochondrial calcium uniporter inhibitor ruthenium red, activator spermine, and mitochondrial permeability transition pore inhibitor cyclosporin A separately, observing the continuous change in absorbance. At last, observing the mitochondrial morphology of each group using transmission electron microscopy.Results Treatment with ruthenium red (5μmol/L), the extent and rate of decline in the absorbance were attenuated. Spermine (100μmol/L) much more enhanced the extent and rate of decline, while cyclosporin A (2μmol/L) reversed this effect. Following transmission electron microscopy, the degree of swelling in the ruthenium red group was attenuated compared with the control group, spermine group was the most severe, however, cyclosporine A plus spermine group was slighter than the spermine group.Conclusion These results indicate that the mitochondrial calcium uniporter plays a role on the mitochondrial permeability transition pore in isolated rat brain cortex mitochondria.