To investigate the influence of the mitochondrial calcium uniporter on the 
mitochondrial permeability transition pore, the present study observed 
mitochondrial morphology in cortical neurons isolated from adult rats using 
transmission electron microscopy, and confirmed the morphology and activity of 
isolated mitochondria by detecting succinic dehydrogenase and monoamine oxidase, 
two mitochondrial enzymes. Isolated mitochondria were treated with either 
ruthenium red, an inhibitor of the uniporter, spermine, an activator of the 
uniporter, or in combination with cyclosporin A, an inhibitor of the 
mitochondrial permeability transition pore. Results showed that ruthenium red 
inhibited CaCl2-induced mitochondrial permeability transition pore opening, 
spermine enhanced opening, and cyclosporin A attenuated the effects of spermine. 
Results demonstrated that the mitochondrial calcium uniporter plays a role in 
regulating the mitochondrial permeability transition pore in mitochondria 
isolated from the rat brain cortex.