XXII. BIOCHEMICKÝ ZJAZD - Jesseniova lekárska fakulta

Lectures
oxidaTIve STrESS aND HEart aGING.
Zuzana Tatarková, Eva Babušíková, Stanislav Kuka, Ján Lehotský, Peter Račay,
Dušan Dobrota and Peter Kaplán
Department of medical biochemistry JLF UK Martin
Aging plays in our life uniquely role and oxidative stress (OS) is considered by many
authors as a major factor in this process. The causes and consequences of aging involve
the interaction of many processes. Mitochondria are the main sources of ROS (reactive
oxygen species) during normal metabolism. ROS production by mitochondria is important
because it underlies oxidative damage in a lot of pathologies and is characterized
by destruction of structural integrity of membrane, leading to a decrease in membrane
fluidity and enzyme activities. Therefore, the objective of our study was to determine
the specific relationship between heart aging and changes in the level of OS, lipid peroxidation
and OS-sensitive enzymes activities. We used three different age groups (6-,
15- and 26-months old rats) which represented adult, old and senescence. The activities
of all respiratory enzymes significantly decreased with the highest activity losses (37%)
in complex IV. Inhibition of citric acid cycle enzymes, a-KGDH and SDH in the hearts of
senescent rats, is also due to reaction of ROS with the thiol groups of these proteins. For
this reason we studied total thiol group content, which decreases by 30%. The whole aging
process was associated with elevation in basal levels of lipid peroxidation-end products,
MDA and HNE. Cells are continually challenged by conditions that cause acute or chronic
stress and there are many antioxidant mechanisms that cope with this situation. Activity
of the Mn-SOD was together with cytosolic CuZn-SOD continuously depressed with age,
but mitochondria creates higher level of MnSOD protein, which possibly could help to
another antioxidant enzymes fight against OS. In all this reasons, OS in mitochondria
may drive myocardial aging. But there are still many processes that we need investigate.
Acknowledgements: This work was supported by grants VEGA 1/0027/08, VEGA 1/0049/09,
VVCE-0064-07.
XXII. Biochemistry Congress, Martin
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