Usselman Charlotte W, Gimon Tamara I, Nielson Chantelle A, Luchyshyn Torri A, Coverdale Nicole S, Van Uum Stan H M, Shoemaker J Kevin
Neurovascular Research Laboratory, School of Kinesiology, Western University, London, Ontario, Canada;
Department of Medicine, Western University, London, Ontario, Canada; Lawson Health Research Institute, Western University, London, Ontario, Canada; and.
Am J Physiol Heart Circ Physiol. 2015 Mar 15;308(6):H664-71. doi: 10.1152/ajpheart.00345.2014. Epub 2014 Dec 19.
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.
本研究旨在探讨性别（男性与女性）和性激素（女性月经周期各阶段）对年轻健康个体交感神经对严重化学反射激活反应性的影响。在基线状态以及再呼吸随后进行最大吸气末屏气期间测量肌肉交感神经活动（MSNA）。在女性中，月经周期黄体中期（ML）的基线MSNA高于卵泡早期（EF）。基线MSNA爆发发生率男性高于女性，而仅在ML期男性和女性的爆发频率及总MSNA相似。化学反射激活在所有参与者中引起MSNA爆发频率、幅度及总活动的分级增加。在女性中，这种交感神经兴奋在EF期大于ML期。女性EF期对化学反射刺激的交感神经兴奋反应也大于男性。尽管如此，总外周阻力在性别和月经周期各阶段之间的变化相似。这表明在化学反射激活期间EF期神经血管转导减弱，从而抵消了过度的交感神经兴奋。化学反射引起的平均动脉压升高在性别和月经周期各阶段之间相似。在急性化学反射刺激期间，神经血管转导降低可能提供一种机制，通过该机制女性相对于男性与呼吸暂停相关的发病率可能会降低。
