Data from: Individuals with higher metabolic rates have lower levels of reactive oxygen species hydrogen peroxide in vivo

There is increasing interest in the effect of energy metabolism on
oxidative stress, but much ambiguity over the relationship between the
rate of oxygen consumption and the generation of reactive oxygen species
(ROS). Production of ROS (such as hydrogen peroxide, H2O2) in the
mitochondria is primarily inferred indirectly from measurements in vitro,
which may not reflect actual ROS production in living animals. Here, we
measured in vivo H2O2 content using the recently developed MitoB probe
that becomes concentrated in the mitochondria of living organisms, where
it is converted by H2O2 into an alternative form termed MitoP; the ratio
of MitoP/MitoB indicates the level of mitochondrial H2O2 in vivo. Using
the brown trout Salmo trutta, we tested whether this measurement of in
vivo H2O2 content over a 24 h-period was related to interindividual
variation in standard metabolic rate (SMR). We showed that the H2O2
content varied up to 26-fold among fish of the same age and under
identical environmental conditions and nutritional states. Interindividual
variation in H2O2 content was unrelated to mitochondrial density but was
significantly associated with SMR: fish with a higher mass-independent SMR
had a lower level of H2O2. The mechanism underlying this observed
relationship between SMR and in vivo H2O2 content requires further
investigation, but may implicate mitochondrial uncoupling which can
simultaneously increase SMR but reduce ROS production. To our knowledge,
this is the first study in living organisms to show that individuals with
higher oxygen consumption rates can actually have lower levels of H2O2.