Genotype dependent and cigarette specific effects on endothelial nitric oxide synthase gene expression and enzyme activity

We explored the interactive effects of endothelial nitric oxide synthase (e NOS) genotypes and cigarette smoking on protein levels and enzyme activity in 33 postpartum placentas. Whilst the eNOS protein levels were lo,ver in t he rare allele (0.48 +/- 0.11, n = 9 vs. 1.05 +/- 0.10, n = 24, P < 0.01), the eNOS enzyme activity was about 7-fold higher in the rare allele (4556.2 +/- 255.4 vs. 621.8 +/- 180.5 cpm/mg/min, P < 0.01). Smokers had lower eNO S protein levels (1.07 +/- 0.09 vs. 0.50 +/- 0.19, P < 0.05) in both allele s, It reduced the eNOS activities only in the rare allele (non-smokers: 614 3.8 +/- 251.2, n = 5, smokers: 2968.5 +/- 259.4, n = 4, 52% reduction, P < 0.01), We conclude that associations between eNOS polymorphism and protein levels and enzyme activities are modifiable by smoking, the effects of smok ing are dependent on the eNOS genotypes, (C) 2000 Federation of European Bi ochemical Societies.