Study of thiobarbituric reactive substances and total reduced glutathione as indices of oxidative stress in chronic smokers with and without chronic obstructive pulmonary disease.

ABSTRACT

BACKGROUND: The imbalance between oxidants and antioxidants is thought to play an important role in the pathogenesis of chronic obstructive pulmonary disease (COPD). METHODS: Biomarkers of lipid oxidation such as thiobarbituric reactive substances (TBARs), total reduced glutathione (GSH) were estimated in chronic smokers with and without COPD, and non-smokers. RESULTS: The following subjects (all males) were studied (i) chronic smokers (32.5 +/- 8.6 pack years) with stable COPD (n = 20; mean age 47.2 +/- 7.8 years); (ii) chronic smokers (6.3 +/- 1.9 pack years) without COPD (n = 20; mean age 35.3 +/- 4.5 years); and (iii) non-smokers (n = 20; mean age 37.5 +/- 5.5 years). The mean TBARs levels (nmol of malondialdehyde per ml of plasma) were higher among smokers with COPD (5.72 +/- 1.02) when compared with smokers without COPD (4.85 +/- 0.97) and non-smokers (2.58 +/- 0.56) (p < 0.001). The mean GSH levels (micromol/mg of protein) were significantly higher in non-smokers (0.163 +/- 0.113) compared to smokers with COPD (0.083 +/- 0.05) and those without COPD (0.050 +/- 0.051) (p < 0.001). There was no statistically significant difference in the plasma GSH levels among smokers with and without COPD (p > 0.05). CONCLUSIONS: Our observations demonstrate increased lipid peroxidation because of oxidative stress due to smoking.