Age-related Changes in Activity of Catalase in Selected Bovine Muscles

Background: The unavoidable consequence of ageing process is oxidative stress which is harmful to cells. Muscles as a post-mitotic cells are especially susceptible for it. They are protected by antioxidants. One of the main antioxidant enzymes is catalase (CAT). Although muscles were extensively examined for antioxidant defense, there is a lack of comparative study regarding CAT activity in skeletal muscles, heart muscle and diaphragm in cows. The aim of present study was investigate the link between age related alterations and antioxidant defense system and confirmation that CAT activity depends on age and type of muscle tissue dependent on metabolic rate. Materials, Methods & Results: Samples of skeletal muscles, heart and diaphragm were collected from healthy HolsteinFriesian cows aged between 14 and 27 months (n = 12; sexually mature) and female calves aged between 2 weeks and 2 months (n = 9; sexually immature) in slaughterhouse. The enzyme activity was measured by spectrophotometric method. Additionally the presence of CAT was confirmed by SDS-PAGE separation and detected by zymography. In current investigation CAT activity in heart and diaphragm showed significantly higher (P < 0.05) values than in skeletal muscles. Moreover, CAT activity was higher in cows than in calves in heart (0.28 +/- 0.044 U /mg protein vs. 0.4 +/- 0.035) as well as in diaphragm (0.27 +/- 0.047 vs 0.37 +/- 0.077), however in skeleton muscles there were no significant differences between examined animals (0.076 +/- 0.016 vs 0.084 +/- 0.0197). According to received results CAT activity increased during aging in heart and diaphragm while in skeleton muscles age-related changes were not observed. Discussion: Skeletal muscles are particularly vulnerable to oxidative stress because they are composed by post-mitotic cells. Moreover, they have also some tendency to accumulate products of oxidative damage during consumption a large amount of oxygen. That is why highly active tissues like skeletal and cardiac muscles are more vulnerable to damage than other tissues. The metabolism of muscle tissues depends on the type of fibers which differ from each other with the concentration of myoglobin as well as resistance to fatigue. Other factors which have the influence on oxidative stress and activity of antioxidant enzymes are age and sex. The age-related changes in antioxidant system in muscles could be different from other tissues like liver, kidney or brain. Taking into consideration the fact that metabolic rate and demands for muscles are significantly different between each other, the examination of CAT activity in different type of bovine muscles (skeleton, diaphragm and heart) was undertaken. In current studies m. semitendinosus as a skeleton muscle was examined. There are some data describing differences between metabolism and contractile fibre type (MHC I proportion) in different parts (proximal, medium, distal) of that muscle which also change with age. Glycolytic metabolism dominated in proximal part while oxidative metabolism in distal part and in both cases the tendency decreased during ageing. The highest CAT activity was found in liver, kidneys, red blood cells and bone marrow, while connective tissue showed the lowest activity of the enzyme. Present study confirms that CAT activity differs between type of examined muscles and may be related to metabolic characteristics of selected muscles. Age-related alterations that appeared may suggest the influence of sex steroids on antioxidative defense mechanisms.