A. Nitric Oxide and Vasodilatory Function
Impairment of vasodilatory function is one of the earliest manifestations of atherosclerotic changes in arteries. In both animal and human models, studies by Celermajer et al. and other investigators have demonstrated that both active and passive cigarette smoke exposure were associated with a decrease in vasodilatory function. In humans, cigarette smoke exposure has been shown to impair endothelium-dependent vasodilation in macrovas-cular beds such as coronary and brachial arteries and in microvascular beds. Nitric oxide (NO), a free radical, is primarily responsible for the vasodilatory function of the endothelium. Using cigarette smoke extract or isolated components such as nicotine, multiple in vitro studies have found that cigarette smoke was associated with decreased NO availability.
B. Oxidation of LDL Cholesterol
Cigarette smoke experimentally increases vascular inflam¬mation, thrombosis, oxidation of LDL cholesterol, and oxidative stress. Nishio et al. indicated that cigarette smoke extract exposure appears to decrease the plasma activity of paraoxonase, an enzyme that protects against LDL oxidation. In a hyperlipidemic rabbit model, Yamaguchi et al. have shown injection of cigarette smoke accelerated atherosclerosis through oxidative modification of LDL.

Страницы: 1 | 2