Open AccessOral contraceptives and menstrual cycle influence autonomic reflex function
Author(s) -
Assadpour Elnaz,
Ivry Ilana,
Wasef Sara,
Adeyinka Baithat,
Murray Kevin R.,
Edgell Heather
Publication year - 2020
Publication title -
physiological reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.918
H-Index - 39
ISSN - 2051-817X
DOI - 10.14814/phy2.14550
Subject(s) - medicine , endocrinology , ventilation (architecture) , reflex , luteal phase , hormone , anesthesia , mechanical engineering , engineering
Progesterone and its analogues are known to influence ventilation. Therefore, the purpose of this study was to investigate the role of endogenous and pharmaceutical female sex hormones in ventilatory control during the activation of the metaboreflex, mechanoreflex, and CO 2 chemoreflex. Women aged 18–30 taking ( n = 14) or not taking ( n = 12) oral contraceptives (OC and NOC, respectively) were tested in the low hormone (LH) and high hormone (HH) conditions corresponding to the early follicular and mid‐luteal phases (NOC) or placebo and high‐dose pills (OC). Women underwent three randomized trials: (a) 3 min of passive leg movement (PLM), (b) 2 min of 40% maximal voluntary handgrip exercise followed by 2 min of post‐exercise circulatory occlusion (PECO), and (c) 5 min of breathing 5% CO 2 . We primarily measured hemodynamics and ventilation. During PLM, the OC group had a smaller pressor response ( p = .012). During PECO, the OC group similarly exhibited a smaller pressor response ( p = .043) and also exhibited a greater ventilatory response ( p = .024). Lastly, in response to breathing 5% CO 2 , women in the HH phase had a greater ventilatory response ( p = .022). We found that OC use attenuates the pressor response to both the metaboreflex and mechanoreflex while increasing the ventilatory response to metaboreflex activation. We also found evidence of an enhanced CO 2 chemoreflex in the HH phase. We hypothesize that OC effects are from the chronic upregulation of pulmonary and vascular β‐adrenergic receptors. We further suggest that the increased cyclic progesterone in the HH phase enhances the chemoreflex.