The objective of this study was to elucidate the possible nature of th
e mechanism underlying the widely observed phenomenon that the rate of
H2O2 production by mitochondria increases during the aging process, u
sing eight muscle mitochondria of the male housefly as a model system.
The protein carbonyl, content of mitochondria increased linearly with
age of the flies, and was also inversely associated with the life exp
ectancy of flies. Exposure of flies to 100% oxygen caused a progressiv
e increase in the level of mitochondrial carbonyl content. The rate of
H2O2 release by such oxidatively damaged mitochondria was higher than
the controls. Similarly, X-irradiation of submitochondrial particles
simultaneously resulted in increased rate of H2O2 production and eleva
ted level of carbonyl content. Results of this and previous studies in
dicate that oxidative damage to mitochondrial membranes may be respons
ible for the age-related increase in mitochondrial H2O2 generation.