Experimental physiology | 2021
Similar inflammatory response and conduit artery vascular function between sexes following induced inflammation.
Abstract
NEW FINDINGS\nWhat is the central question of this study? Are there sex differences in vascular function following induced inflammation when estrogen is typically similar between sexes? What is the main finding and its importance? The present study suggests no sex differences in conduit artery vascular responses to acutely induced inflammation during the low estrogen phase of the menstrual cycle in premenopausal women. However, women exhibit lower microvascular function as compared with men. Overall, the results underpin estrogen s role in previously observed sex differences and the importance of reporting when in the hormonal cycle women are studied.\n\n\nABSTRACT\nSex differences in cardiovascular disease incidence in premenopausal women and age-matched men are thought to be due to the cardioprotective influence of estrogen. However, limited knowledge exists regarding sex differences following acute inflammation when estrogen concentrations are lower in women. Thus, sex differences in vascular responses to induced inflammation were evaluated when estrogen concentrations are typically lower in women. In 15 women and 14 men, interleukin-6 (IL-6) concentrations and vascular function via brachial artery flow-mediated dilation (FMD) were assessed at baseline (BL), 24 hours (24H), and 48 hours (48H) following influenza vaccine administration. Women were studied when circulating estrogen concentrations are typically low (early follicular phase or placebo phase of hormonal contraception). Following induced inflammation, both sexes exhibited an increase in IL-6 concentrations at 24H (BL v 24H: women 0.563 (0.50) v 1.141 (0.65) pg/mL; men 0.385 (0.17) v 1.113 (0.69) pg/mL p<0.05) that returned to near baseline concentrations by 48H (BL v 48H: p>0.05). There were no sex differences in FMD, allometrically scaled FMD, or IL-6 concentrations at any time point (p>0.05). Notably, women exhibited significantly lower microvascular function than men at every time point (p<0.05; reactive hyperemic area under the curve (AU) women BL: 35512 (14916), 24H: 34428 (14292), 48H: 39467 (13936); men BL: 61748 (27324), 24H: 75028 (29051), 48H: 59532 (13960)). When estrogen concentrations are typically lower in women, women exhibited similar inflammatory response and conduit artery function, but lower microvascular response to reactive hyperemia, as compared with age-matched men. This article is protected by copyright. All rights reserved.