Effect of Sex on Cardiovascular Responses to Acute Sympathoexcitatory Stressors

Abstract

Over the past twenty years, an increasing number of studies have compared baseline cardiovascular regulation between men and women. These studies have provided strong support for an effect of sex on cardiovascular outcomes, and implicate the sympathetic nervous system as a mediator of many of these differences. However, many of these studies have been conducted under baseline conditions, despite the fact that humans are seldom in a true “baseline” state (i.e., quiet, supine rest). Therefore, the purpose of this study was to investigate the effect of sex on cardiovascular responses to sympatho‐excitatory stimuli in young healthy individuals. We examined cardiovascular responses to the cold pressor test (CPT) and a voluntary end‐expiratory apnea (APN) in 5 women and 4 men. We hypothesized that women would demonstrate a reduced change in total peripheral resistance (TPR) and therefore blood pressure (BP) responses to these stimuli compared with men. Men and women were of similar age (men: 24 ± 2 y, women: 24 ± 1; p=0.8) and BMI (men: 26 ± 6 kg/m2, women: 22 ± 1; p=0.2). Baseline mean arterial pressure (MAP) was higher in men than women (87 ± 7 vs77 ± 4 mmHg, respectively; p=0.03), while baseline TPR (men: 25.7 ± 2.7 vs women: 23.2 ± 6.6 mmHg/L/min; p=0.5) and cardiac output (3.4 ± 0.4 vs 3.5 ± 0.9 L/min; p=0.9) were similar between the sexes. CPT was associated with a significant increase in MAP from baseline which was not different between the sexes (men: 90 ± 3 vs women: 92 ± 13mmHg; main effect of condition: p=0.03, effect of sex: p=0.7). Likewise, TPR increased in response to CPT, but again this response did not differ between the sexes (men: 27.0 ± 7.1, vs women: 25.8 ± 5.4 mmHg/L/min; main effect of condition: p=0.04, effect of sex: p=0.3). APN‐EX was associated with a similar increase in DBP (men: 83 ± 6 vs women: 69 ± 25 mmHg; main effect of condition: p=0.03, effect of sex: p=0.3) as well as TPR (men: 33.0 ± 4.8 vs women: 29.0 ± 13.9 mmHg/L/min; main effect of condition: p=0.01, effect of sex: p=0.6). In conclusion, cardiovascular responses to the CPT, a generalized sympathetic stressor, as well as to APN, which activates the chemoreflex, were similar between the young healthy men and women. These data refute our hypothesis, and suggest that cardiovascular responsiveness during these sympatho‐excitatory stimuli does not differ between the sexes.Support or Funding InformationThis project was supported by a Natural Sciences and Engineering Research Council Discovery Grant (CWU). TEA and YC were supported by the McGill Department of Kinesiology and Physical Education Graduate Excellence Fellowship.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.