Hypercapnia attenuates inspiratory amplitude and expiratory time responsiveness to hypoxia in vagotomized and vagal-intact rats

Tin, Chung; Song, Gang; Poon, Chi‐Sang

doi:10.1016/j.resp.2012.01.008

Cited by 21 publications

(30 citation statements)

References 64 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…These observations are in agreement with other studies [80,81,82]. Tidal volume (V T ) and respiratory frequency ( f R ) increase at higher stimulus.…”

Section: Experimental Data and Protocolsupporting

confidence: 93%

Novel Modeling of Work of Breathing for Its Optimization During Increased Respiratory Efforts

Higuita

Mañanas

Sánchez

et al. 2016

IEEE Systems Journal

View full text Add to dashboard Cite

One of the most complex physiological systems whose modeling is still an open study is the respiratory control system where different models have been proposed based on the criterion of minimizing the work of breathing (WOB). The aim of this study is twofold: to compare two known models of the respiratory control system which set the breathing pattern based on quantifying the respiratory work; and to assess the influence of using direct-search or evolutionary optimization algorithms on adjustment of model parameters. This study was carried out using experimental data from a group of healthy volunteers under CO 2 incremental inhalation, which were used to adjust the model parameters and to evaluate how much the equations of WOB follow a real breathing pattern. This breathing pattern was characterized by the following variables: tidal volume, inspiratory and expiratory time duration and total minute ventilation. Different optimization algorithms were considered to determine the most appropriate model from physiological viewpoint. Algorithms were used for a double optimization: firstly, to minimize the WOB and secondly to adjust model parameters. The performance of optimization algorithms was also evaluated in terms of convergence rate, solution accuracy and precision. Results showed strong differences in the performance of opti- mization algorithms according to constraints and topological features of the function to be optimized. In breathing pattern optimization, the sequential quadratic programming technique (SQP) showed the best performance and convergence speed when respiratory work was low. In addition, SQP allowed to implement multiple non-linear constraints through mathematical expressions in the easiest way. Regarding parameter adjustment of the model to experimental data, the evolutionary strategy with covariance matrix and adaptation (CMA-ES) provided the best quality solutions with fast convergence and the best accuracy and precision in both models. CMAES reached the best adjustment because of its good performance on noise and multi-peaked fitness functions. Although one of the studied models has been much more commonly used to simulate respiratory response to CO 2 inhalation, results showed that an alternative model has a more appropriate cost function to minimize WOB from a physiological viewpoint according to experimental data.

show abstract

“…These observations are in agreement with other studies [80,81,82]. Tidal volume (V T ) and respiratory frequency ( f R ) increase at higher stimulus.…”

Section: Experimental Data and Protocolsupporting

confidence: 93%

Novel Modeling of Work of Breathing for Its Optimization During Increased Respiratory Efforts

Higuita

Mañanas

Sánchez

et al. 2016

IEEE Systems Journal

View full text Add to dashboard Cite

show abstract

“…In anesthetized mammals central and peripheral chemoreceptors typically have roughly additive effects on ventilation (99, 124). A hypoadditive hypercapnic-hypoxic interaction on breathing has also been reported, first in a hypothermic arterially perfused midcollicular transected rat preparation (75) and, more recently, in urethane-anesthetized atropinized rats (434). …”

Section: Interplay Between Peripheral and Central Chemoreceptorsmentioning

confidence: 83%

Regulation of Breathing and Autonomic Outflows by Chemoreceptors

Guyenet

2014

Comprehensive Physiology

269

293

View full text Add to dashboard Cite

Lung ventilation fluctuates widely with behavior but arterial PCO2 remains stable. Under normal conditions, the chemoreflexes contribute to PaCO2 stability by producing small corrective cardiorespiratory adjustments mediated by lower brainstem circuits. Carotid body (CB) information reaches the respiratory pattern generator (RPG) via nucleus solitarius (NTS) glutamatergic neurons which also target rostral ventrolateral medulla (RVLM) presympathetic neurons thereby raising sympathetic nerve activity (SNA). Chemoreceptors also regulate presympathetic neurons and cardiovagal preganglionic neurons indirectly via inputs from the RPG. Secondary effects of chemoreceptors on the autonomic outflows result from changes in lung stretch afferent and baroreceptor activity. Central respiratory chemosensitivity is caused by direct effects of acid on neurons and indirect effects of CO2 via astrocytes. Central respiratory chemoreceptors are not definitively identified but the retrotrapezoid nucleus (RTN) is a particularly strong candidate. The absence of RTN likely causes severe central apneas in congenital central hypoventilation syndrome. Like other stressors, intense chemosensory stimuli produce arousal and activate circuits that are wake- or attention-promoting. Such pathways (e.g., locus coeruleus, raphe, and orexin system) modulate the chemoreflexes in a state-dependent manner and their activation by strong chemosensory stimuli intensifies these reflexes. In essential hypertension, obstructive sleep apnea and congestive heart failure, chronically elevated CB afferent activity contributes to raising SNA but breathing is unchanged or becomes periodic (severe CHF). Extreme CNS hypoxia produces a stereotyped cardiorespiratory response (gasping, increased SNA). The effects of these various pathologies on brainstem cardiorespiratory networks are discussed, special consideration being given to the interactions between central and peripheral chemoreflexes.

show abstract

“…A hypoadditive hypercapnic-hypoxic interaction on breathing has also been reported, first in a hypothermic arterially-perfused midcollicular transected rat preparation (Day and Wilson, 2009) and more recently in urethane-anesthetized atropinized rats (Tin et al, 2012). …”

Section: Integration Between Peripheral and Central Chemoreceptor mentioning

confidence: 87%

Chemoreception and asphyxia-induced arousal

Guyenet

Abbott

2013

Respiratory Physiology & Neurobiology

View full text Add to dashboard Cite

Arousal protects against the adverse and potentially fatal effects of asphyxia during sleep. Asphyxia stimulates the carotid bodies and central chemoreceptors but the sequence of events leading to arousal is uncertain. In this review, the theoretical mechanisms leading to arousal from sleep are briefly summarized and the issue of whether central respiratory chemoreceptors (CRCs) or other types of CO2-responsive CNS neurons contribute to asphyxia-induced arousal is discussed. We focus on the role of the retrotrapezoid nucleus, the raphe and the locus coeruleus and emphasize the anatomical and neurophysiological evidence which suggests that these putative central chemoreceptors could contribute to arousal independently of their effects on breathing. Finally, we describe recent attempts to test the contribution of specific brainstem pathways to asphyxia-induced arousal using optogenetic and other tools and the possible contribution of a group of hypoxia-sensitive brainstem neurons (the C1 cells) to breathing and arousal.

show abstract

Hypercapnia attenuates inspiratory amplitude and expiratory time responsiveness to hypoxia in vagotomized and vagal-intact rats

Cited by 21 publications

References 64 publications

Novel Modeling of Work of Breathing for Its Optimization During Increased Respiratory Efforts

Novel Modeling of Work of Breathing for Its Optimization During Increased Respiratory Efforts

Regulation of Breathing and Autonomic Outflows by Chemoreceptors

Chemoreception and asphyxia-induced arousal

Contact Info

Product

Resources

About