EFFECT OF NICOTINE AND COTININE ON THE SUSCEPTIBILITY TO IN-VITRO OXIDATION OF LDL IN HEALTHY NON SMOKERS AND SMOKERS

Cigarette smoke of which the major component is nicotine plays an impo rtant role in the development of cardiovascular diseases. To study the effect of in vitro incubation of LDL with nicotine and its metabolite , cotinine on a copper-induced peroxidation, we monitored the formatio n of conjugated dienes, hydroperoxides and thiobarbituric acid-reactiv e substances production. The LDL studied were taken from six non-smoke rs (aged 41.5 years) and six smokers who consumed at least ten cigaret tes per day (40.7 years). LDL oxidation with CuSO4 showed that cigaret te smoking promotes LDL susceptibility to peroxidative modification. D uring the peroxidation of LDL with nicotine (0 to 5 mmol/l) acid CuSO4 (5 mu mol/l), the formation of hydroperoxides decreased when nicotine concentrations increased and the production of TBARS increased in a c oncomitant manner. The results showed that the presence of nicotine de stabilized the production of hydroperoxides in LDL and increased the f ormation of secondary oxidation products. On the other hand, cotinine had no effect on LDL oxidative susceptibility in smokers and non-smoke rs. (C) 1998 Published by Elsevier Science B.V. All rights reserved.