How important is the CO2 chemoreflex for the control of breathing? Environmental and evolutionary considerations

Santin, Joseph M.

doi:10.1016/j.cbpa.2017.09.015

Cited by 10 publications

(3 citation statements)

References 133 publications

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“…Nevertheless, we recently showed that, in accordance with a longer apnea duration, the chemoreflex is reduced in swimmers’ athletes compared to a control condition ( Arce-Álvarez et al, 2021 ). Of note, this adaptative process is not only observed in mammals, if not also in amphibian and reptile species ( Santin, 2017 ), showing neuroplasticity impacting CO2/O2 chemoreflex. Indeed, it has been speculated to increase breath-hold duration to lengthen dive time adaptively for these animals.…”

Section: Introductionmentioning

confidence: 96%

Chemoreflex Control as the Cornerstone in Immersion Water Sports: Possible Role on Breath-Hold

et al. 2022

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Immersion water sports involve long-term apneas; therefore, athletes must physiologically adapt to maintain muscle oxygenation, despite not performing pulmonary ventilation. Breath-holding (i.e., apnea) is common in water sports, and it involves a decrease and increases PaO2 and PaCO2, respectively, as the primary signals that trigger the end of apnea. The principal physiological O2 sensors are the carotid bodies, which are able to detect arterial gases and metabolic alterations before reaching the brain, which aids in adjusting the cardiorespiratory system. Moreover, the principal H+/CO2 sensor is the retrotrapezoid nucleus, which is located at the brainstem level; this mechanism contributes to detecting respiratory and metabolic acidosis. Although these sensors have been characterized in pathophysiological states, current evidence shows a possible role for these mechanisms as physiological sensors during voluntary apnea. Divers and swimmer athletes have been found to displayed longer apnea times than land sports athletes, as well as decreased peripheral O2 and central CO2 chemoreflex control. However, although chemosensitivity at rest could be decreased, we recently found marked sympathoexcitation during maximum voluntary apnea in young swimmers, which could activate the spleen (which is a reservoir organ for oxygenated blood). Therefore, it is possible that the chemoreflex, autonomic function, and storage/delivery oxygen organ(s) are linked to apnea in immersion water sports. In this review, we summarized the available evidence related to chemoreflex control in immersion water sports. Subsequently, we propose a possible physiological mechanistic model that could contribute to providing new avenues for understanding the respiratory physiology of water sports.

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Section: Introductionmentioning

confidence: 96%

Chemoreflex Control as the Cornerstone in Immersion Water Sports: Possible Role on Breath-Hold

et al. 2022

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“…Breathing is a complicated behavior controlled by multiple sensory and neuromodulatory feedback systems that allow ventilation to match metabolic demands. One part of the respiratory control system that has received much attention is the sensory system that drives ventilation when CO 2 rises in the arterial blood and brain (Guyenet & Bayliss, ; Santin, ). Along with the motor components of the network, the CO 2 chemosensory system remains inactive during the winter because the partial pressure of CO 2 in the blood (and likely the intestinal fluid of the brain) falls below values that stimulate chemosensory neurons (Santin, Watters, Putnam, & Hartzler, ; Ultsch, Reese, & Stewart, ).…”

Section: Open Questions and The Use Of Hibernating Animals As Models mentioning

confidence: 99%

Motor inactivity in hibernating frogs: Linking plasticity that stabilizes neuronal function to behavior in the natural environment

Santin

2019

Developmental Neurobiology

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All animals must generate reliable neuronal activity to produce adaptive behaviors in an ever-changing environment. Neural systems are thought to achieve this goal, in part, through cellular and synaptic plasticity mechanisms that stabilize electrophysiological functions. Despite strong evidence for a role in regulating neuronal properties, these plasticity mechanisms have been difficult to link to natural behaviors in animals. In this review, I discuss how animals that inhabit extreme environments can address this challenge. As an example, I highlight recent work from frogs that stop breathing for several months during hibernation and, in response, use classic mechanisms of stabilizing plasticity to support respiratory motor output shortly after emergence. Furthermore, I describe problems for neuronal stability that may benefit from the study of hibernators: how circuits with variable modes of output control stabilizing mechanisms over long time scales and why some neural systems mount robust compensatory responses and others do not. By continuing to appreciate how diverse animal groups overcome challenges in the natural environment, we will broaden our view of the role that plasticity mechanisms play in stabilizing the nervous system. K E Y W O R D SAMPA receptor, control of breathing, hibernation, homeostatic plasticity, motor systems

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“…36 Medullary CO 2 chemoreceptors are commonly viewed as major tonic inputs to eupnea, but there are several examples among rodents and other species or with pharmaco-genetic lesioning, in which the hypercapnic ventilatory response is reduced or even negligible while the eupneic air-breathing PaCO 2 is normal. [37][38][39] Acute optogenetic lesioning of RTN CO 2 -sensitive neurons resulted in a significant CO 2 retention in the awake rodent, but this was due only to increased breathing frequency and dead-space ventilation with no significant reductions in V T or V ̇E. 40 This tachypneic response is not usually indicative of a chemoreceptor influence.…”

Section: Role Of Chemoreceptors In Healthmentioning

confidence: 99%

Control of Breathing

Dempsey

Welch

2023

Semin Respir Crit Care Med

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Substantial advances have been made recently into the discovery of fundamental mechanisms underlying the neural control of breathing and even some inroads into translating these findings to treating breathing disorders. Here, we review several of these advances, starting with an appreciation of the importance of V̇A:V̇CO2:PaCO2 relationships, then summarizing our current understanding of the mechanisms and neural pathways for central rhythm generation, chemoreception, exercise hyperpnea, plasticity, and sleep-state effects on ventilatory control. We apply these fundamental principles to consider the pathophysiology of ventilatory control attending hypersensitized chemoreception in select cardiorespiratory diseases, the pathogenesis of sleep-disordered breathing, and the exertional hyperventilation and dyspnea associated with aging and chronic diseases. These examples underscore the critical importance that many ventilatory control issues play in disease pathogenesis, diagnosis, and treatment.

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How important is the CO2 chemoreflex for the control of breathing? Environmental and evolutionary considerations

Cited by 10 publications

References 133 publications

Chemoreflex Control as the Cornerstone in Immersion Water Sports: Possible Role on Breath-Hold

Chemoreflex Control as the Cornerstone in Immersion Water Sports: Possible Role on Breath-Hold

Motor inactivity in hibernating frogs: Linking plasticity that stabilizes neuronal function to behavior in the natural environment

Control of Breathing

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