VARIED PREVALENCE OF AGE-ASSOCIATED MITOCHONDRIAL-DNA DELETIONS IN DIFFERENT SPECIES AND TISSUES - A COMPARISON BETWEEN HUMAN AND RAT

The prevalence in tissues of mtDNA deletions was compared by PCR betwe en humans and rats of similar ''biological ages''. Pairs of species-sp ecific primers were used which spanned similar portions of the human a nd rat mtDNA genomes. There were much fewer PCR products amplified fro m rat mtDNA than hom human mtDNA in each of the three tissues initiall y analysed: heart, liver and skeletal muscle. By contrast, many more P CR products were amplified from rat kidney than from human kidney. The refore, while there were far more deletions in heart, liver and skelet al muscle of humans than in corresponding rat tissues, the prevalence of mtDNA deletions was markedly less in human kidney than in rat kidne y. The data also indicate that human kidney contains less mtDNA deleti ons than heart, liver and skeletal muscle in humans; whereas in rat ki dney there are more mtDNA deletions than in those three tissues of rat . It is further suggested that, when utilising rodents as experimental models for human ageing, the appropriate tissues should be considered , since not all tissues of rats accumulate mtDNA mutations in the same manner as those Of humans. (C) 1997 Academic Press