THE EFFECTS OF SMOKING ON ANTIOXIDANT DEFENSE SYSTEM AND MEMBRANE FREE FATTY-ACID CONTENT OF ERYTHROCYTES AND PLASMA-LIPID PARAMETERS - PROTECTIVE ROLE OF ANTIOXIDANT VITAMINS

Activities of antioxidant enzymes were measured in the erythrocytes fr om 15 smokers and 15 non-smokers. Superoxide dismutase (SOD) and catal ase (CAT) activities were found lower but, glutathione peroxidase (GSH -Px) activity unchanged in the erythrocytes from smokers compared with non-smokers. Levels of thiobarbituric acid-reactive substances (TBARS ) were however higher both in erythrocytes and plasma from smokers. An tioxidant vitamin (vitamins E and C) supplementation for the period of 15 days caused significant increases in the activities of all antioxi dant enzymes and decreases in the TEARS levels of erythrocytes and of blood plasma in smoker group. It has been observed that smoking caused significant changes in the concentrations of plasma lipid fractions a s well. In this regard, total cholesterol level (TC) was found unchang ed, LDL cholesterol and triglyceride (TG) levels increased and HDL cho lesterol decreased in the plasma from smokers compared with non-smoker s. Vitamin supplementation caused a significant increase in HDL choles terol and a decrease in LDL cholesterol in plasma from smokers. The vi tamins normalised the HDL/LDL ratio in smokers. Fatty acid composition of erythrocyte membranes from smokers also presented significant chan ges. In particular, oleic acid (18:1) was almost absent in the erythro cyte membranes of smokers. In contrast, the relative amount of stearic acid (18:0) was found to be significantly increased but, those of som e fatty acids (12:0, 14:0, 14:1 and 16:0) decreased in the erythrocyte membranes of smokers. Results suggested that enzymatic antioxidant de fence system of erythrocytes was depressed and the erythrocytes were e xposed to oxidant stress due to smoking. Increased plasma TEARS levels indicated that not only erythrocytes but also some other tissues and cells might be exposed to the radical stress by cigarette smoke. Smoki ng also caused significant changes in the levels of plasma lipid param eters and antioxidant vitamins partly protected erythrocytes against s uch harmful effects of smoking by scavenging free radical species and by activating and/or inducing antioxidant enzymes. (C) 1997 Elsevier S cience Inc.