The purpose of this study was to investigate the decline in rat liver mitochondria
respiration found in adult rats compared to younger ones, and to find a link between
this respiratory impairment and a tissue hypothyroidism state. To this end, hepatic
concentration and serum levels of triiodothyronine were measured in postpubertal rats
(60 days old) and adult rats (180 days old). In addition, in these rats we measured
oxidative phosphorylation in homogenate together with coupled and uncoupled respiration
in isolated mitochondria using succinate or durohydroquinone as substrate. We found
that mitochondria from adult rats consumed less oxygen compared to younger rats due
to lower electron transport chain and phosphorylating system activity. In addition,
we found that in state 4 condition, mitochondria from adult rats consumed less oxygen
than mitochondria from young rats. Finally, we found a decrease in liver triiodothyronine
concentration in adult rats.
In conclusion, the results of this study show that hepatic mitochondria in adult rats
have a decreased ATP synthesis capacity and proton permeability, both consistent with
the tissue hypothyroidism found in the liver of adult rats.
Key words:
Homogenate Respiration - Mitochondrial Protein Mass - Uncoupled Respiration - Cytochrome
Content - Serum Triiodothyronine Level
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G. Liverini
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