Variations in endothelial function and arterial compliance during the menstrual cycle.

Area of Science:

• Cardiovascular Physiology
• Reproductive Endocrinology
• Vascular Biology

Background:

• Premenopausal women exhibit cardioprotection, potentially linked to female sex hormones.
• The precise cardiovascular effects of hormonal fluctuations during the menstrual cycle remain incompletely understood.

Purpose of the Study:

• To investigate dynamic changes in vascular function across different phases of the menstrual cycle in healthy premenopausal women.
• To correlate these vascular changes with hormonal patterns throughout the cycle.

Main Methods:

• Noninvasive assessments including flow-mediated dilatation (FMD), laser Doppler velocimetry (LDV) with acetylcholine (ACh) and nitroprusside iontophoresis, and whole body arterial compliance (WBAC).
• Measurements were taken during four distinct menstrual phases: early follicular (EF), late follicular (LF), early luteal (EL), and late luteal (LL).
• Hormone levels were monitored to confirm cycle phase and ovulation.

Main Results:

• Flow-mediated dilatation (FMD), LDV response to ACh, and WBAC exhibited significant cyclical variations.
• These parameters increased from the EF to LF phase, decreased sharply in the EL phase, and recovered in the LL phase.
• Pulse wave velocity showed no significant changes, while nitroprusside-induced vasodilation decreased only from EF to EL.

Conclusions:

• Endothelial reactivity and arterial compliance are significantly modulated by the hormonal shifts of the menstrual cycle.
• Menstrual phase is a critical factor for interpreting endothelial function data in premenopausal women.
• These findings offer insights into sex-based differences in cardiovascular risk and disease mechanisms.