The effect of nicotine on aortic endothelium. A quantitative ultrastructural study.

This study used quantitative electron microscopy to assess ultrastructural features of endothelial injury occurring with exposure to nicotine. Fourteen mice were given nicotine in their drinking water for 5 weeks. The dose (5 mg/kg body wt/day) was equivalent to a human smoking 50-100 cigarettes/day. A control group of mice was unexposed to nicotine over the same period. Stereological analysis of electron micrographs of endothelium from both groups revealed that the nicotine-exposed endothelium showed greater cytoplasmic vacuolation, mitochondrial swelling and subendothelial oedema than the control endothelium. In addition the intercellular cleft morphology was significantly (P less than 0.005) less complex than in the control endothelium. This difference in cleft morphology suggests the nicotine-exposed endothelium is more permeable than the control endothelium. The ultrastructural differences noted in this study are indicative of endothelial damage, and provide structural evidence to support the hypothesis that nicotine contributes to the pathogenesis of arterial disease in smokers.