During acute chemoreflex stress, women in the early-follicular phase exhibited significantly greater increases in muscle sympathetic nerve activity compared to both women in the midluteal phase and men.
Cross-Sectional (n=18)
Randomized crossover for menstrual phases in women
No
Do sex and menstrual cycle phases affect sympathetic responsiveness to severe chemoreflex activation in young, healthy individuals?
Reduced neurovascular transduction during the early-follicular phase in women offsets exaggerated sympathoexcitation during acute chemoreflex stimulation, potentially attenuating apnea-associated morbidity relative to men.
p-value: p=<0.05
This study aimed to examine the effects of sex (males vs. females) and sex hormones (menstrual cycle phases in women) on sympathetic responsiveness to severe chemoreflex activation in young, healthy individuals. Muscle sympathetic nerve activity (MSNA) was measured at baseline and during rebreathing followed by a maximal end-inspiratory apnea. In women, baseline MSNA was greater in the midluteal (ML) than early-follicular (EF) phase of the menstrual cycle. Baseline MSNA burst incidence was greater in men than women, while burst frequency and total MSNA were similar between men and women only in the ML phase. Chemoreflex activation evoked graded increases in MSNA burst frequency, amplitude, and total activity in all participants. In women, this sympathoexcitation was greater in the EF than ML phase. The sympathoexcitatory response to chemoreflex stimulation of the EF phase in women was also greater than in men. Nonetheless, changes in total peripheral resistance were similar between sexes and menstrual cycle phases. This indicates that neurovascular transduction was attenuated during the EF phase during chemoreflex activation, thereby offsetting the exaggerated sympathoexcitation. Chemoreflex-induced increases in mean arterial pressure were similar across sexes and menstrual cycle phases. During acute chemoreflex stimulation, reduced neurovascular transduction could provide a mechanism by which apnea-associated morbidity might be attenuated in women relative to men.
Usselman et al. (Sat,) conducted a cross-sectional in Healthy (n=18). Acute chemoreflex stress (hypoxic-hypercapnic apnea) vs. Men vs. Women (early-follicular and midluteal phases) was evaluated on Muscle sympathetic nerve activity (MSNA) response to chemoreflex activation (p=<0.05). During acute chemoreflex stress, women in the early-follicular phase exhibited significantly greater increases in muscle sympathetic nerve activity compared to both women in the midluteal phase and men.