Cardiovascular Stress Response Laboratory, School of Kinesiology and Health Studies, Queen's University , Kingston, Ontario , Canada.
J Appl Physiol (1985). 2019 Feb 1;126(2):314-321. doi: 10.1152/japplphysiol.00729.2018. Epub 2018 Nov 1.
Acutely imposed oscillatory shear stress (OSS) reduces reactive hyperemia flow-mediated dilation (RH-FMD) in conduit arteries of men; however, whether a similar impairment occurs in women or with FMD in response to a controlled, sustained shear stress stimulus (SS-FMD) is unknown. The purpose of this study was to determine the impact of OSS on RH-FMD and SS-FMD in men and women. OSS was provoked in the brachial artery using a 30-min forearm cuff inflation (70 mmHg). Healthy men [ n = 16, 25 yr (SD 3)] and women [ n = 16, 21 yr (SD 2)] completed the OSS intervention twice (separate days). Brachial artery endothelial function was assessed pre- and postintervention via either RH-FMD or 6 min of handgrip SS-FMD using Duplex ultrasound. The RH-FMD stimulus was calculated as shear rate area under the curve 60 s postdeflation (SR), whereas SS-FMD shear rate was targeted to produce a similar stimulus pre- and postintervention. The OSS intervention decreased RH-FMD in both sexes [men: 6.2% (SD 3.4) to 5.2% (SD 3.0); women: 5.4% (SD 2.0) to 3.1% (SD 1.8), P < 0.001), although this was accompanied by a reduced SR. There was no significant effect of the intervention on RH-FMD with SR as a covariate ( P = 0.310). Handgrip exercise elicited a similar stimulus before and after the intervention ( P = 0.287) in men and women ( P = 0.873). Men demonstrated blunted SS-FMD [4.8% (SD 1.9) to 3.2% (SD 1.9), P < 0.001], whereas women displayed preserved SS-FMD following the intervention [3.5% (SD 1.9) to 4.0% (SD 1.9), P = 0.061]. The lower SS-FMD in men but not women following OSS provides evidence of sex differences in the effects of OSS on conduit artery endothelial function. NEW & NOTEWORTHY Acute exposure to oscillatory shear stress induces transient endothelial dysfunction in men; however, whether women experience similar impairments is unknown. Following acutely imposed oscillatory shear stress, there was a decrease in flow-mediated dilation stimulated by a physiologically relevant sustained increase in shear stress in men but not in premenopausal women. These findings demonstrate, for the first time in humans that there are sex differences in the impact of oscillatory shear stress on endothelial function.
急性施加的振荡切应力（OSS）降低男性大血管中的反应性充血介导的舒张（RH-FMD）；然而，女性是否存在类似的损伤，或者 FMD 是否对受控的持续切应力刺激（SS-FMD）有反应尚不清楚。本研究的目的是确定 OSS 对男性和女性的 RH-FMD 和 SS-FMD 的影响。通过前臂袖带充气（70mmHg）在肱动脉中诱发 OSS，健康男性[ n = 16，25 岁（SD 3）]和女性[ n = 16，21 岁（SD 2）]在两次（不同的日子）完成 OSS 干预。使用双功能超声在干预前后通过 RH-FMD 或 6 分钟的手部握力 SS-FMD 评估肱动脉内皮功能。RH-FMD 刺激计算为充气后 60 秒的切率面积下曲线（SR），而 SS-FMD 切率旨在在干预前后产生相似的刺激。OSS 干预降低了两性的 RH-FMD[男性：6.2%（SD 3.4）至 5.2%（SD 3.0）；女性：5.4%（SD 2.0）至 3.1%（SD 1.8），P < 0.001]，尽管这伴随着 SR 的降低。当以 SR 为协变量时，干预对 RH-FMD 没有显著影响（P = 0.310）。在男性和女性中，手部握力运动在干预前后产生相似的刺激（P = 0.287）（P = 0.873）。男性的 SS-FMD 减弱[4.8%（SD 1.9）至 3.2%（SD 1.9），P < 0.001]，而女性在干预后显示出保存的 SS-FMD[3.5%（SD 1.9）至 4.0%（SD 1.9），P = 0.061]。在 OSS 后，男性的 SS-FMD 较低，但女性的 SS-FMD 没有降低，这提供了证据表明，OSS 对大血管内皮功能的影响存在性别差异。新内容和值得注意的内容：急性暴露于振荡切应力会导致男性内皮功能短暂障碍；然而，女性是否存在类似损伤尚不清楚。在急性施加振荡切应力后，男性中由生理相关的持续切应力增加引起的血流介导的舒张减少，但在绝经前女性中没有减少。这些发现首次在人类中表明，振荡切应力对内皮功能的影响存在性别差异。
