Purpose: The NADPH oxidase system produces superoxide (intrinsic oxidative load) while smoking is a well-established extrinsic oxidative factor. Carriers of the G allele (AG or GG) at position −930 of the CYBA gene of NADPH oxidase produce increased amounts of superoxide. We investigated the effect of intrinsic (NADPH produced) versus extrinsic (smoking) oxidative stress on arterial elastic properties.

Methods: 132 normotensives (83 males, mean age 40.6 years) were divided in group A: non/light smokers (<5 pack-years, 67 subjects) and group B: heavy smokers (≥5 pack-years, 65 subjects). Augmentation index (AI) was measured using a validated device The A-to-G substitution was typed by BbvI digestion of specific PCR products amplified from DNA.

Results: The two groups did not differ regarding sex, peripheral pressures, BMI and lipids (p=NS). Group A had lower AI than group B (16.5±12.5% vs 23.1±12.2%, p<0.01). In group A, the prevalence of AA vs AG+GG genotypes was 19.4% and 80.6; when compared to AA subjects, AG+GG subjects demonstrated higher levels of AI (AA:8.7±6.2% vs AG+GG: 18.4±13%; p=0.01). In group B, the prevalence of AA vs AG+GG was 29.2% and 70.8%; AI levels did not vary between the two subgroups (AA:24.3±11.3% vs AG+GG: 22.6±12.6%; p=NS).

Conclusion: In non/light smokers presence of the G allele accounts for deteriorated arterial elastic properties. This is not the case in heavy smokers, as wave reflections are equally impaired irrespectively of the G allele presence. These findings underscore the need for further research into the interplay between intrinsic, extrinsic oxidative stress and arterial function.