Postnatal intermittent hypoxia alters baroreflex function in adult rats

Soukhova-O'Hare, Galia K.; Cheng, Zixi; Roberts, Andrew M.; Gozal, David

doi:10.1152/ajpheart.00767.2005

Cited by 59 publications

(48 citation statements)

References 52 publications

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“…The observations during sleep appear to be in line with the selective impairment of baroreflex response to hypotensive agents found in untreated OSA during wakefulness [38]. Overall, the current study confirms that long-term CPAP treatment is necessary to reverse chronic autonomic dysfunction during sleep [1,4,5,8] and wakefulness [6,8,39,40], possibly in relation to recovery of cardiac vagal fibres after protracted resolution of intermittent hypoxia [41]. Thus, the autonomic dysfunction associated with severe OSA appears not to be as readily reversible as the decreased BRS in snorers [17].…”

Section: Discussionsupporting

confidence: 85%

Baroreflex control of heart rate during sleep in severe obstructive sleep apnoea: effects of acute CPAP

Bonsignore

Parati

Insalaco³

et al. 2006

Eur Respir J

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Baroreflex control of heart rate during sleep (baroreflex sensitivity; BRS) has been shown to be depressed in obstructive sleep apnoea (OSA), and improved after treatment with continuous positive airway pressure (CPAP). Whether CPAP also acutely affects BRS during sleep in uncomplicated severe OSA is still debatable.Blood pressure was monitored during nocturnal polysomnography in 18 patients at baseline and during first-time CPAP application. Spontaneous BRS was analysed by the sequence method, and estimated as the mean sequence slope.CPAP did not acutely affect mean blood pressure or heart rate but decreased cardiovascular variability during sleep. Mean BRS increased slightly during CPAP application (from 6.5¡2.4 to 7.5¡2.9 ms?mmHg -1 ), mostly in response to decreasing blood pressure. The change in BRS did not correlate with changes in arterial oxygen saturation or apnoea/hypopnoea index. The small change in baroreflex control of heart rate during sleep at first application of continuous positive airway pressure in severe obstructive sleep apnoea was unrelated to the acute resolution of nocturnal hypoxaemia, and might reflect autonomic adjustments to positive intrathoracic pressure, and/or improved sleep architecture. The small increase in baroreflex control of heart rate during sleep may be of clinical relevance as it was accompanied by reduced cardiovascular variability, which is acknowledged as an independent cardiovascular risk factor.

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Section: Discussionsupporting

confidence: 85%

Baroreflex control of heart rate during sleep in severe obstructive sleep apnoea: effects of acute CPAP

Bonsignore

Parati

Insalaco³

et al. 2006

Eur Respir J

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“…(22,23) Alternatively, the association between pre-eclampsia and SDB could be mediated by fetal hypoxia. (24)(25)(26)(27)(28)(29)(30),(31) Pre-eclampsia may cause chronic fetal hypoxia directly via maternal vascular insufficiency with subsequent reduction of fetal oxygen delivery due to placental insufficiency, or may be acting as a marker for intermittent maternal hypoxia associated with maternal SDB. The association of childhood SDB with mild but not severe pre-eclampsia is of particular interest because it is consistent with proposed differences in the biology of mild versus severe pre-eclampsia.…”

Section: Discussionmentioning

confidence: 99%

Prenatal and Neonatal Risk Factors for Sleep Disordered Breathing in School-Aged Children Born Preterm

Hibbs

Johnson

Rosen

et al. 2008

The Journal of Pediatrics

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Objectives-Previously published data from the Cleveland Children's Sleep and Health Study (CCSHS) demonstrated that preterm infants are especially vulnerable both to sleep disordered breathing (SDB) and its neurocognitive sequelae at age 8-11 years. In this analysis, we aimed to identify the components of the neonatal medical history associated with childhood SDB among children born prematurely.Study design-This analysis focuses on the 383 children in the population-based CCSHS cohort who were born <37 weeks gestational age and who had technically acceptable sleep studies performed at ages 8-11 years (92% of all preterm children). Logistic regression was used to evaluate the associations between candidate perinatal and neonatal risk factors and the presence of childhood SDB by sleep study.Results-Twenty-eight preterm children (7.3%) met the definition for SDB at age 8-11 years. Having a single mother and mild maternal pre-eclampsia were strongly associated with SDB in unadjusted and race-adjusted models. Unadjusted analyses also identified xanthine use and CPR and/ or intubation in the delivery room as potential risk-factors for SDB. We did not find a significant link between traditional markers of severity of neonatal illness --such as gestational age, birth weight, intraventricular hemorrhage (IVH), bronchopulmonary dysplasia (BPD), or duration of ventilation --and childhood SDB at school age.Conclusions-These results represent a first step in identifying prenatal and neonatal characteristics which place preterm infants at higher risk for childhood SDB. The strong association between mild pre-eclampsia and childhood SDB underscores the importance of research aimed at understanding in utero risk factors for neurorespiratory development. Corresponding Author: Anna Maria Hibbs, MD, MSCE, Division of Neonatology, Rainbow Babies & Children's Hospital, 11100 Euclid Avenue, Suite 3100, Cleveland, email: annamaria.hibbs@case.edu. Edited by AJ and WFB Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. (1) Furthermore, the association between sleep disordered breathing (SDB) and childhood cognitive impairment is stronger in preterm than term infants. (8) The mechanisms by which prematurity predisposes children to SDB are unknown. The association may be mediated by altered development of the lungs, airway, or nervous system. In this analysis, we aimed to identify the components of the prenatal and neonatal medical history associated with SDB occurring in children in the CCSHS studied at ages 8-11 years who had been born prematurely. NIH Public Access METHODSThe CCSHS is a po...

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confidence: 89%

“…In addition, we showed that vagal cardiac motor neurons in the nucleus ambiguus projecting to cardiac ganglia play an important role in the baroreflex control of the HR (10 -12). More recently, we found that postnatal CIH exposures led to altered baroreflex function in adult rats, and that the associated reduction of vagal efferent axon projections to cardiac ganglia could contribute to the long-term modification in baroreflex function (46).Although progress has occurred in the understanding of alterations in baroreceptor reflex function following intermittent hypoxia (24,29,30,42,46,47,49), very little is currently known about the structural and functional changes of sensory afferent, central and efferent components of the reflex, and their molecular underpinnings. Mice are particularly useful mammalian models that are not only susceptible to genetic manipulation but can also be used in physiological, anatomical, cellular, and molecular studies (5, 6).…”

mentioning

confidence: 99%

Chronic intermittent hypoxia impairs baroreflex control of heart rate but enhances heart rate responses to vagal efferent stimulation in anesthetized mice

Lin¹,

Liu²,

Gozal³

et al. 2007

American Journal of Physiology-Heart and Circulatory Physiology

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Z. Chronic intermittent hypoxia impairs baroreflex control of heart rate but enhances heart rate responses to vagal efferent stimulation in anesthetized mice. Am J Physiol Heart Circ Physiol 293: H997-H1006, 2007. First published March 23, 2007; doi:10.1152/ajpheart.01124.2006.-Chronic intermittent hypoxia (CIH) leads to increased sympathetic nerve activity and arterial hypertension. In this study, we tested the hypothesis that CIH impairs baroreflex (BR) control of heart rate (HR) in mice, and that decreased cardiac chronotropic responsiveness to vagal efferent activity contributes to such impairment. C57BL/6J mice were exposed to either room air (RA) or CIH (6-min alternations of 21% O2 and 5.7% O2, 12 h/day) for 90 days. After the treatment period, mice were anesthetized (Avertin) and arterial blood pressure (ABP) was measured from the femoral artery. Mean ABP (MABP) was significantly increased in mice exposed to CIH (98.7 Ϯ 2.5 vs. RA: 78.9 Ϯ 1.4 mmHg, P Ͻ 0.001). CIH increased HR significantly (584.7 Ϯ 8.9 beats/min; RA: 518.2 Ϯ 17.9 beats/min, P Ͻ 0.05). Sustained infusion of phenylephrine (PE) at different doses (0.1-0.4 g/min) significantly increased MABP in both CIH and RA mice, but the ABP-mediated decreases in HR were significantly attenuated in mice exposed to CIH (P Ͻ 0.001). In contrast, decreases in HR in response to electrical stimulation of the left vagus nerve (30 A, 2-ms pulses) were significantly enhanced in mice exposed to CIH compared with RA mice at low frequencies. We conclude that CIH elicits a sustained impairment of baroreflex control of HR in mice. The blunted BR-mediated bradycardia occurs despite enhanced cardiac chronotropic responsiveness to vagal efferent stimulation. This suggests that an afferent and/or a central defect is responsible for the baroreflex impairment following CIH. nucleus ambiguus; obstructive sleep apnea; cardiac ganglia OBSTRUCTIVE SLEEP APNEA (OSA) is associated with substantial morbidities involving the central nervous system and cardiovascular systems (43, 50). Chronic intermittent hypoxia (CIH), which epitomizes one of the characteristics of OSA, has been used as a useful model for OSA (18,41). Regarding the latter, of particular physiological and clinical importance, is baroreflex control of heart rate (HR) (baroreflex sensitivity). Attenuation of baroreflex sensitivity is closely associated with several clinical conditions, including heart failure (16, 25, 44), and is considered as an independent risk factor for cardiac failure and sudden death (22). Therefore, an increased understanding of the physiological and anatomical characteristics of CIHassociated changes of the baroreflex pathways is clearly needed for improved formulation of interventional strategies aimed at reducing the morbidity associated with OSA.Previously, we demonstrated that baroreflex control of the HR was significantly reduced following CIH in Fisher 344 (F344) young adult rats (29). In addition, we showed that vagal cardiac motor neurons in the nucleus ambiguus projecting to cardiac...

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Postnatal intermittent hypoxia alters baroreflex function in adult rats

Cited by 59 publications

References 52 publications

Baroreflex control of heart rate during sleep in severe obstructive sleep apnoea: effects of acute CPAP

Baroreflex control of heart rate during sleep in severe obstructive sleep apnoea: effects of acute CPAP

Prenatal and Neonatal Risk Factors for Sleep Disordered Breathing in School-Aged Children Born Preterm

Chronic intermittent hypoxia impairs baroreflex control of heart rate but enhances heart rate responses to vagal efferent stimulation in anesthetized mice

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