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Effect of CO2 on free-radical damage
Dušková, Eliška ; Kalous, Martin (referee) ; Wilhelm, Jiří (advisor)
CO2, known for its role in acid-base regulations, is a mediator of peroxynitrite-induced oxidative damage and it also enhances Cu,Zn-SOD's antioxidant activity. These two means, by which CO₂ affects free-radical damage, are well-explored, but there are many other mechanisms. When CO2 joins in free radical reactions, carbonate radical is often produced. The carbonate radical specifically damages substrates, but it is not possible to generalize, if the effect is pro-oxidant or antioxidant. A protective role of CO2 has been observed during lipid peroxidation and during peroxynitrite-induced oxidation of DNA, when the carbonate radical caused injury to specific bases, but in the same time it prevented DNA strand breaks. Similarly, CO2 prevented peroxynitrite- induced protein fragmentation as well as it caused injury to specific aminoacids. These observations are mostly based on experiments in a chemical system, which means under simplified conditions. In vivo, CO2 exerts much more mechanisms to affect free radical reactions. Under more complex conditions, as cell culture is, there was an increase of oxidative stress after CO2 exposure. Increased concentration of CO2 causes a change in erythrocyte's function and an increase of oxidative stress on the organism's level.
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