Exercise increases the production of reactive oxygen species, which may damage a number of cell constituents. Organisms have developed a sophisticated antioxidant system for protection against reactive oxygen species. Our aim was to compare the adaptive responses of antioxidant mechanisms and the blood redox status of two groups of athletes, long-distance and short-distance runners. Thiobarbituric acid reactive substances, catalase activity and total antioxidant capacity was measured in the serum, while reduced and oxidized glutathione as well as their ratio were determined in blood hemolysates. Serum catalase activity (P<0.001) was found to be three times higher in long-distance compared to short-distance runners (25.4 vs. 8.9 μmol · min-1 ·ml-1), whereas the two groups did not differ in the other markers. Catalase activity also correlated significantly with maximal oxygen consumption in long-distance runners. In conclusion, we report here that long-distance and short-distance runners exhibit similar blood redox status judged by several oxidative stress indices, except for the much higher activity of catalase in long-distance runners. This different effect of the two training modules on catalase activity of long-distance runners might be partly due to the high oxygen load imposed during their repeated prolonged exercise bouts.
Paraoxonase (PON1) is a serum enzyme with an antioxidant function, protecting the low density lipoproteins (LDL) from oxidative modifications. Because diabetic patients are at greater risk of oxidative stress, we investigated the effect of PON1 55 methione (M)/leucine (L) and PON1 192 glutamine (A)/arginine (B) polymorphisms on oxidant-
antioxidant system in 213 individuals with type 2 diabetes mellitus and 116 non-diabetic control subjects from Turkish population were included in the study. Polymerase chain reaction (PCR), restriction fragment length polymorphism (RFLP), and agarose gel electrophoresis techniques were used to determine the PON1 genotypes. Thiobarbituric acid reactive substances (TBARS), conjugated dienes levels in the serum and glutathione (GSH) levels in whole blood were measured spectrophotometrically. In both groups PON1 192 AA and PON1 55 MM genotypes had higher TBARS,
conjugated dienes levels and lower GSH levels, whereas PON1 192 BB and PON1 55 LL genotypes had lower TBARS, conjugated diene levels and higher GSH level than other genotypes. We thus conclude that PON1 192 BB and PON1 55 LL alleles have protective effect against oxidative stress.