The extended longevity of bats, despite their high metabolic rate, may provide insight to patterns and mechanisms of ageing. I tested the free radical theory of ageing as an explanation for the extreme longevity of the little brown bat, Myotis lucifugus (maximum lifespan potential "MLSP" = 34 yrs). In a comparative study, I measured whole-organism oxygen consumption and mitochondrial hydrogen peroxide production in brain, heart, and kidney tissues from M. lucifugus and short-tailed shrews, Blarina brevicauda (MLSP = 2 yrs). As predicted by the free radical theory of ageing, M. lucifugus produced approximately half the amount of hydrogen peroxide as B. brevicauda. Additionally, I compared oxygen consumption and hydrogen peroxide production of adult (~ 1 yr) and juvenile (fully developed and fledged young of the year) Myotis lucifugus to assess oxidative damage to mitochondria (measured as an increase in hydrogen peroxide production) due to the high metabolic rate associated with flight. Contrary to my prediction, juveniles had significantly higher levels of hydrogen peroxide production than adults. I propose that the decreased free radical production in adults is the result of within-individual selection of efficient mitochondria due to selective pressure created by the high energetic demands of flight.
free radical theory