Characterization of mitochondrial cardiomyopathy in wild type (wt), mtDNA mutator (mut), UCP2-deficient wild type (ko) and mtDNA mutator (dm) mice.

<p>(A) Histological examination of cardiomyocytes from mut and dm mice. TEM – transmission electron micrographs. Arrows indicate lipid droplets, arrowheads abnormal mitochondria. COX/SDH - Enzyme histochemical staining for cytochrome <i>c</i> oxidase (COX) and succinate dehydrogenase (SDH) activities in heart. (B) Quantification of mitochondrial mass in transmission electron micrographs. (C) Relative expression levels of <i>Nppa</i> and <i>Nppb</i>, markers of heart failure. (D) Relative <i>Fgf21</i> mRNA expression levels in heart. (E) Relative <i>Fgf21</i> mRNA expression levels in liver and skeletal muscle. All analyses were performed on 25-week-old mice. Bars indicate mean level ± standard error of the mean (S.E.M.). Asterisks indicate level of statistical significance (*p<0.05 **p<0.01 ***p<0.001, Student's <i>t</i>-test).