Chronic smoking prevents amelioration of endothelial function in the course of the menstrual cycle.

BACKGROUND Smoking is the most important modifiable cardiovascular risk factor in young women. The aim of this study was to investigate whether tobacco use influences physiological changes in endothelial function during the menstrual cycle. METHODS AND RESULTS Flow-mediated dilation (FMD) and nitro-mediated dilation (NMD) were assessed in healthy smoking and non-smoking women, by high-resolution ultrasound at 3 time points during the menstrual cycle: at menstruation, in the mid-follicular phase, and in the mid-luteal phase. A total of 25 women (12 non-smokers, 13 smokers) completed the study protocol. FMD did not show differences between smoking and non-smoking women at menstruation and the mid-follicular phase. At the mid-luteal phase, however, FMD was significantly reduced in smoking when compared with non-smoking women. NMD did not differ between smoking and non-smoking women, nor between the different cycle phases. CONCLUSIONS In healthy women, smoking eliminates the physiological amelioration of endothelial function during the menstrual cycle. This study underlines the importance of an exact description of menstrual cycle phase and smoking status in studies investigating endothelial function in premenopausal women.