The effects of menstrual phase on brachial artery endothelial function after mental stress in young women

Abstract

The changes in ovarian hormones throughout the menstrual cycle have direct actions on endothelial function. However, very limited human data are available regarding the alterations in endothelial function at baseline or after mental stress during the discrete phases of the menstrual cycle. We examined whether the menstrual cycle influences the endothelial function after mental stress in young women. Female university students were tested during three phases of a normal menstrual cycle. Delineation of the three phases occurred as follows: (1) the early follicular phase; (2) the late follicular phase; (3) the middle luteal phase. Non-invasive measurement of peripheral endothelial function was determined by flow-mediated dilation (FMD) testing in the brachial artery during reactive hyperemia using echo and Doppler ultrasound. After the measurements of basal levels, they were subjected to mental stress evoked by the modified Stroop Color Word Test (CWT) in 10 min. The CWT induced arterial pressure and heart rate (HR) elevations, and a slight vasoconstriction of brachial artery. The measurements of flow-mediated dilation (FMD) and maximal blood flow (%) were repeated at 5 min and 30 min after the CWT. Basal FMD and FMD after the CWT tended to vary during the three phases cyclically.These findings suggest the importance of menstrual phase in the interpretation of data on endothelial function.