Peripheral chemoreflex contribution to ventilatory long‐term facilitation induced by acute intermittent hypercapnic hypoxia in males and females

Abstract

Ventilatory long-term facilitation (vLTF) refers to respiratory neuroplasticity that develops following intermittent hypoxia in both healthy and clinical populations. r A sustained hypercapnic background is argued to be required for full vLTF expression in humans. r We determined whether acute intermittent hypercapnic hypoxia elicits vLTF during isocapnic-normoxic recovery in healthy males and females. We further assessed whether tonic peripheral chemoreflex drive is necessary and contributes to the expression of vLTF. r Following 40 min of intermittent hypercapnic hypoxia, minute ventilation was increased throughout 50 min of isocapnic-normoxic recovery. Inhibition of peripheral chemoreflex drive with hyperoxia attenuated the magnitude of vLTF. r Males and females achieve vLTF through different respiratory recruitment patterns.

Intermittent hypercapnic hypoxia: a model to study human respiratory motor plasticity?

“…First, the findings of Vermeulen et al . (2020) are in opposition to a previous report declaring absence of IHH‐induced ventilatory LTF (Diep et al . 2007).…”

“…In a study recently published in The Journal of Physiology , Vermeulen et al . (2020) tested the hypothesis that IH, consisting of hypercapnic and hypoxic intervals (IHH), elicits an increase in that persists beyond the stimulus period (i.e. ventilatory LTF).…”

Cardiorespiratory plasticity in humans following two patterns of acute intermittent hypoxia

“…(2020) and Vermeulen et al. (2020), indicates that elevated CO 2 may play an important role in the development of MAP‐LTF, which may be facilitated by peripheral chemoreceptor potentiation and/or central chemoreceptor activation. We did not use elevated CO 2 in our study, but rather clamped isocapnia throughout.…”

“…Our sample size precludes a formal sex‐differences analysis. Previous work suggests that males and females both develop vLTF (Vermeulen et al., 2020) while MAP‐LTF is observed in young males but not young females following IHx (Jacob et al., 2020). Consequently, further research is required to further understand how EDEs during and following IHx differ between sexes and at different time points of the menstrual cycle.…”

Hypoxic Respiratory Chemoreflex Control in Young Trained Swimmers

“…The increase in CB chemoreceptors activity elicits an increase in minute ventilation (V E ), sympathetic activity, arterial blood pressure (BP), and heart rate (HR) to cope with metabolic demands (Iturriaga et al, 2016). Therefore, as swimmers are subjected to intermittent apneas during training session, it is possible that the apnea-dependent repetitive hypoxic-hypercapnic stimuli could induce a depressed respiratory neuroplasticity (Vermeulen et al, 2020) and therefore impact on peripheral chemoreflex drive and possibly on apnea time.…”