• Siu P Ho, Moira Chan-Yeung, Kathy K M Chow, Mary S M Ip, and Judith C W Mak.
• Division of Respiratory and Critical Care Medicine, Department of Medicine, The University of Hong Kong, Hong Kong SAR, China.
• Respirology. 2005 Jun 1; 10 (3): 305-9.

ObjectiveSpecific antioxidant enzymes play a vital role in regulating and maintaining oxidant species. The aim of this study was to determine these antioxidant enzyme activities (i.e. catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GPx)) in erythrocytes from a group of healthy Chinese subjects and to study the influence of age, gender and smoking habits on the enzyme activities.MethodologyChinese healthy subjects (n = 276) were grouped according to their age range, gender differences and smoking habits. Antioxidant enzyme activities were measured spectrophotometrically using standard kinetic methods.ResultsThere was a significant decrease in erythrocyte GPx activity in ever-smokers compared with non-smokers (47.10 +/- 1.33 mU/g haemoglobin (Hb) vs. 51.41 +/- 1.64 mU/g Hb, P < 0.05). Age-related significant increases in erythrocyte CAT and SOD activities were found in non-smokers but not in ever-smokers. There was no age-related difference in erythrocyte GPx activity in either non-smokers or ever-smokers. Among those >60 years old, erythrocyte CAT and GPx activities were significantly lower in ever-smokers than in non-smokers (29.70 +/- 3.07 mU/g Hb vs. 41.63 +/- 4.92 mU/g Hb (P < 0.05), and 47.55 +/- 2.00 mU/g Hb vs. 55.30 +/- 3.60 mU/g Hb (P < 0.05), respectively). It was also found that females had higher erythrocyte GPx activity than males but this difference did not reach significance in non-smokers.ConclusionFrom the results of this study, it is concluded that oxidative stress seems to be present in elderly ever-smokers among the Chinese population.

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