School of Kinesiology, University of British Columbia, Vancouver, British Columbia, Canada.
J Appl Physiol (1985). 2012 Mar;112(5):737-47. doi: 10.1152/japplphysiol.00727.2011. Epub 2011 Dec 15.
We hypothesized that resting and exercise ventilatory chemosensitivity would be augmented in women when estrogen and progesterone levels are highest during the luteal phase of the menstrual cycle. Healthy, young females (n = 10; age = 23 ± 5 yrs) were assessed across one complete cycle: during early follicular (EF), late follicular (LF), early luteal, and mid-luteal (ML) phases. We measured urinary conjugates of estrogen and progesterone daily. To compare values of ventilatory chemosensitivity and day-to-day variability of measures between sexes, males (n = 10; age = 26 ± 7 yrs) were assessed on 5 nonconsecutive days during a 1-mo period. Resting ventilation was measured and hypoxic chemosensitivity assessed using an isocapnic hypoxic ventilatory response (iHVR) test. The hypercapnic ventilatory response was assessed using the Read rebreathing protocol and modified rebreathing tests. Participants completed submaximal cycle exercise in normoxia and hypoxia. We observed a significant effect of menstrual-cycle phase on resting minute ventilation, which was elevated in the ML phase relative to the EF and LF phases. Compared with males, resting end-tidal CO(2) was reduced in females during the EF and ML phases but not in the LF phase. We found that iHVR was unaffected by menstrual-cycle phase and was not different between males and females. The sensitivity to chemical stimuli was unaffected by menstrual-cycle phase, meaning that any hormone-mediated effect is of insufficient magnitude to exceed the inherent variation in these chemosensitivity measures. The ventilatory recruitment threshold for CO(2) was generally lower in women, which is suggestive of a hormonally related lowering of the ventilatory recruitment threshold. We detected no effect of menstrual-cycle phase on submaximal exercise ventilation and found that the ventilatory response to normoxic and hypoxic exercise was quantitatively similar between males and females. This suggests that feed-forward and feed-back influences during exercise over-ride the effects of naturally occurring changes in sex hormones.
我们假设，在女性月经周期的黄体期，当雌激素和孕激素水平达到最高时，静息和运动通气化学敏感性会增强。健康的年轻女性（n=10；年龄=23±5 岁）在一个完整周期内进行评估：在卵泡早期（EF）、卵泡晚期（LF）、黄体早期和中期（ML）。我们每天测量尿液中雌激素和孕激素的结合物。为了比较男女之间通气化学敏感性和日常测量值的变异性，10 名男性（n=10；年龄=26±7 岁）在一个月的 5 天内进行了评估。使用等碳酸血症缺氧通气反应（iHVR）测试测量静息通气，评估缺氧化学敏感性。使用 Read 再呼吸方案和改良再呼吸测试评估高碳酸血症通气反应。参与者在常氧和低氧下完成亚最大周期运动。我们观察到月经周期阶段对静息分钟通气的显著影响，ML 阶段的通气量高于 EF 和 LF 阶段。与男性相比，EF 和 ML 阶段女性静息呼气末二氧化碳减少，但 LF 阶段没有减少。我们发现，iHVR 不受月经周期阶段的影响，男女之间也没有差异。对化学刺激的敏感性不受月经周期阶段的影响，这意味着任何激素介导的影响都不足以超过这些化学敏感性测量值的固有变异性。CO2 的通气募集阈值通常在女性中较低，这表明与激素相关的通气募集阈值降低。我们没有检测到月经周期阶段对亚最大运动通气的影响，并且发现男女之间对常氧和低氧运动的通气反应在数量上是相似的。这表明，运动期间的前馈和反馈影响超过了自然发生的性激素变化的影响。
