Chronic intermittent hypoxia‐induced hypertension: An expired hypothesis laid to rest?

Active expiration and chronic intermittent hypoxia‐induced hypertension: A hypothesis that still breathes!

“…In our recent study (Bazilio, Bonagamba, Moraes, & Machado, ), which was the focus of the Viewpoint by O´Connor et al. (), we documented that the incidence of active expiration was higher in awake CIH‐exposed hypertensive rats than in control animals (11 versus 3% of all respiratory cycles during wakefulness), but it was not observed in non‐REM and REM sleep.…”

“…The main issue addressed here is the contribution of an enhancement of the expiratory modulation of sympathetic activity to the development of neurogenic hypertension in rats submitted to chronic intermittent hypoxia (CIH). Considering that active expiration associated with sympathetic overactivity was characterized in the in situ preparation of rats submitted to CIH, the specific question presented by O´Connor, Lucking, and O´Halloran () in their recent Viewpoint was: is active expiration really contributing to sympathetic overactivity and hypertension in rats submitted to CIH?…”

Bugs, breathing and blood pressure: microbiota–gut–brain axis signalling in cardiorespiratory control in health and disease

“…Separate studies convincingly demonstrated that exposure to an extended duration of severe CIH in guinea-pigs manifested in the establishment of hypertension and tachycardia, without carotid body sensitisation (Docio et al 2018). These observations illustrate that sites other than the carotid bodies contribute to cardiorespiratory and autonomic impairments following exposure to CIH (Docio et al 2018;Lucking et al 2018;AlMarabeh et al 2019;OʼConnor et al 2019b), which could reasonably arise from effects at the level of the microbiota.…”

“…2019; OʼConnor et al . 2019 b ), which could reasonably arise from effects at the level of the microbiota.…”

Reply: The two faces of active expiration: a case of mistaken identity!

“…We drew focus in our viewpoint (O'Connor, Lucking & O'Halloran, ) to the persistent expression of hypertension across the sleep–wake cycle in animals exposed to chronic intermittent hypoxia (CIH), with evidence of active expiration only in wakefulness (Bazilio, Bongamba, Moraes & Machado, ). Our intent was to emphasize that active expiration, defined as the motor recruitment of abdominal muscles in support of enhanced pulmonary ventilation, was not obligatory for the continued manifestation of high blood pressure following exposure to CIH.…”