AIM:To investigate whether mitochondrial DNA(mtDNA) and nuclear DNA(nDNA) damage increase with age in rat hearts and to explore the changes of DNA polymerase γ(Polγ) in rat hearts.METHODS:Total DNA,RNA and proteins of hearts were isolated.Damages of mtDNA and nDNA were examined with quantitative polymerase chain reaction(qPCR) assay combined with EvaGreen.Gene expressions of mRNA and protein in Polγ were detected with real-time polymerase chain reaction(RT-PCR) and Western blot analysis,and the levels of 8-...