Free radical generation and oxidative stress with ageing and exercise: Differential effects in the myocardium and liver

Abstract

Reactive oxygen species and other oxidants are implicated in the mechanisms of biological ageing and exercise-induced tissue damage. The present study examined the effects of ageing and an acute bout of exercise on intracellular oxidant generation, lipid peroxidation, protein oxidation and glutathione (GSH) status in the heart and liver of young adult (8 month, N=24) and old (24 month, N=24) male Fischer 344 rats. Young rats ran on treadmill at 25 m min-1, 5% grade until exhaustion (55.4+/-2.7 min), whereas old rats ran at 15 m min-1, 5% until exhaustion (58.0+/-2.7 min). Rate of dichlorofluorescin (DCFH) oxidation, an indication of intracellular oxidant production, was significantly higher in the homogenates of aged heart and liver compared with their young counterparts. In the isolated heart and liver mitochondria, ageing increased oxidant production by 29 and 32% (P<0.05), respectively. Acute exercise increased oxidant production in the aged heart but not in the liver. When nicodinamide dinucleotide phosphate (reduced), adenosine diphosphate and Fe3+ were included in the assay, DCFH oxidation rate was 47 and 34% higher (P<0.05) in the aged heart and liver homogenates, respectively, than the young ones. The age differences in the induced state reached 83 and 140% (P<0.01) in isolated heart and liver mitochondria, respectively. Lipid peroxidation was increased in the aged liver and exercised aged heart, whereas protein carbonyl content was elevated only in the aged heart (P<0.05). Although our data using DCFH method probably underestimated cellular oxidant production because of time delay and antioxidant competition, it is clear that oxidative stress was enhanced in both heart and liver with old age. Furthermore, aged myocardium showed greater susceptibility to oxidative stress after heavy exercise.

Swim exercise training and adaptations in the antioxidant defense system of myocardium of old rats: relationship to swim intensity and duration

“…Physical exercise can increase ROS production in the heart (Ji, 1994;Bejma et al, 2000) since O consumption increases ROS at the electron 2 transport chain, although it may account for only 2-5% of the total oxygen (Tiidus and Houston, 1995). In addition to training intensity and duration, another important parameter that we have addressed in this study is to elucidate the regional responses, but not the whole heart, to exercise.…”

Lipid Peroxidation Potential and Antioxidants in the Heart Tissue of .BETA.-Alanine- or Taurine-Treated Old Rats

“…trolled by several factors such as availability of substrates in the form of unsaturated fatty acids, the presence/absence of peroxidation inducers and inhibitors of free radical reactions (32). The heart is known to have a low total reactive antioxidant potential (34) and an ability to upregulate antioxidant defences and to repair accumulated peroxidative damage (7,35). Therefore, the heart may have high susceptibility to prooxidant stimuli.…”

Determination of mitochondrial reactive oxygen species: methodological aspects

“…A more recent work has stressed the effect of cytochrome C as potent catalyst of DCF formation, suggesting that the fluorescence observed in dying cells could be related to increased cytosolic cytochrome C content [54]. Despite these considerations, limiting the validity of the method, several applications have been proposed and the determination of fluorescence is performed commonly with a fluorimeter [55][56][57][58], either a flow cytofluorimeter [59], an image analysis system [60], or a confocal microscope [61].…”