The influence of long-term hormonal contraception and smoking on plasma concentrations of nitrites and nitrates.

Background: Higher estrogen levels in premenopausal women have a protective effect against arteriosclerosis. In contrast, hormonal contraceptives are often connected with an increased cardiovascular risk, and opinions differ on whether or not smoking increases this risk. The aim of this study was to determine the influence of oral hormonal contraceptives and smoking on the production of nitric oxide metabolites (nitrites/nitrates).

Material/methods: We investigated plasma concentrations of nitrites and nitrates in a group of 24 young women using hormonal contraceptives and a group of the same size of women not using such contraception. Both groups were further divided into smokers and non-smokers. The measurements of nitrites and nitrates were performed by a sensitive high-performance liquid chromatography method with two connected detectors.

Results: Plasma nitrate levels in women using hormonal contraceptives were lower in comparison with the control group of women not using such contraceptives. A statistically significant difference was also found when comparing nitrate concentrations between both groups of female smokers as well as between both groups of non-smokers. The lowest values were recorded in female smokers simultaneously using oral contraceptives.

Conclusions: We have demonstrated lower plasma concentrations of nitrites and nitrates in contrast with the control group in premenopausal women using oral contraceptives in the long-term. Hormonal contraception and simultaneous smoking substantially decreases the plasma concentrations of nitric oxide metabolites (nitrites/nitrates), which can be evidence of vascular homeostasis defect and increased cardiovascular risk.