From: Doug Skrecky (oberon@vcn.bc.ca)
Date: Sun Feb 14 1999 - 05:37:46 MST
Authors
Herrero A. Barja G.
Institution
Department of Animal Biology-II (Animal Physiology), Faculty of Biology,
Complutense University, Madrid, Spain.
Title
H2O2 production of heart
mitochondria and aging rate are slower in canaries and
parakeets than in mice: sites of free radical generation and mechanisms
involved.
Source
Mechanisms of Ageing & Development. 103(2):133-46, 1998 Jun 15.
Abstract
Birds have a maximum longevity (MLSP) much higher than mammals of similar
body size in spite of their high metabolic rates. In this study, State 4 and
State 3 rates of H2O2 production were lower
in canary (MLSP = 24 years) and parakeet (MLSP = 21 years) than in mouse
(MLSP = 3.5 years) heart mitochondria.
Studies using specific inhibitors of the respiratory chain indicate that free
radical generation sites at Complexes I and III are responsible for these
differences. Main mechanisms lowering H2O2
production in these birds are a low rate of
mitochondrial oxygen consumption in the parakeet and a low
mitochondrial free radical leak in the canary. Strong
increases in H2O2 production during active
respiration (State 3) released by addition of ADP to
pyruvate/malate-supplemented mitochondria are avoided in
three species because the free radical leak decreases during the transition
from State 4 to State 3 respiration. These results, together with those
previously obtained in pigeons and in various mammalian species, suggest that
the rate of mitochondrial free radical
production correlates better with the rate of aging and the
MLSP than the metabolic rate. They also suggest that a low rate of
mitochondrial H2O2
production is a general characteristic of birds, animals
showing very slow aging rates.
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