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https://www.readbyqxmd.com/read/27906839/endothelin-contributes-to-the-blood-pressure-rise-triggered-by-hypoxia-in-severe-obstructive-sleep-apnea
#1
Christophe Janssen, Atul Pathak, Guido Grassi, Philippe van de Borne
BACKGROUND: Obstructive sleep apnea (OSA) is strongly correlated with an increased risk of systemic hypertension. However, the link between systemic hypertension and nocturnal apneas remains incompletely understood. Animal studies suggest an implication of the endothelin system. The aim of the present study is to determine if endogenous endothelin plays a role in the increase in blood pressure observed during hypoxic episodes in OSA patients, in addition to peripheral chemoreflex and neural sympathetic activation...
January 2017: Journal of Hypertension
https://www.readbyqxmd.com/read/27861919/consequences-of-maternal-omega-3-polyunsaturated-fatty-acid-supplementation-on-respiratory-function-in-rat-pups
#2
Luana Tenorio-Lopes, Cécile Baldy, Alexandra Jochmans-Lemoine, Océane Mercier, Olivier Pothier-Piccinin, Tommy Seaborn, Vincent Joseph, Isabelle Marc, Richard Kinkead
Most preterm infants present respiratory instabilities and apneas owing to incomplete development of the neural circuits that control breathing. Because omega-3 polyunsaturated fatty acids (n-3 PUFA) benefit brain development, we hypothesized that n-3 PUFA supplementation (via maternal diet) improves respiratory function in rat pups. Pups received n-3 PUFA supplementation from an enriched diet (13 g kg(-1) of n-3 PUFA) administered to the mother from birth until experiments were performed (postnatal days 10-11)...
November 11, 2016: Journal of Physiology
https://www.readbyqxmd.com/read/27836648/sex-differences-in-sleep-disordered-breathing-in-adults
#3
REVIEW
Tijana Lozo, Dragana Komnenov, M Safwan Badr, Jason H Mateika
The prevalence of sleep disordered breathing is greater in men compared to women. This disparity could be due to sex differences in the diagnosis and presentation of sleep apnea, and the pathophysiological mechanisms that instigate this disorder. Women tend to report more non-typical symptoms of sleep apnea compared to men, and the presentation of apneic events are more prevalent in rapid compared to non-rapid eye movement sleep. In addition, there is evidence of sex differences in upper airway structure and mechanics and in neural mechanisms that impact on the control of breathing...
November 9, 2016: Respiratory Physiology & Neurobiology
https://www.readbyqxmd.com/read/27815038/phenotypes-in-obstructive-sleep-apnea-a-definition-examples-and-evolution-of-approaches
#4
REVIEW
Andrey V Zinchuk, Mark J Gentry, John Concato, Henry K Yaggi
Obstructive sleep apnea (OSA) is a complex and heterogeneous disorder and the apnea hypopnea index alone can not capture the diverse spectrum of the condition. Enhanced phenotyping can improve prognostication, patient selection for clinical trials, understanding of mechanisms, and personalized treatments. In OSA, multiple condition characteristics have been termed "phenotypes." To help classify patients into relevant prognostic and therapeutic categories, an OSA phenotype can be operationally defined as: "A category of patients with OSA distinguished from others by a single or combination of disease features, in relation to clinically meaningful attributes (symptoms, response to therapy, health outcomes, quality of life)...
October 12, 2016: Sleep Medicine Reviews
https://www.readbyqxmd.com/read/27797160/pathogenesis-of-central-and-complex-sleep-apnoea
#5
REVIEW
Jeremy E Orr, Atul Malhotra, Scott A Sands
Central sleep apnoea (CSA) - the temporary absence or diminution of ventilatory effort during sleep - is seen in a variety of forms including periodic breathing in infancy and healthy adults at altitude and Cheyne-Stokes respiration in heart failure. In most circumstances, the cyclic absence of effort is paradoxically a consequence of hypersensitive ventilatory chemoreflex responses to oppose changes in airflow, that is elevated loop gain, leading to overshoot/undershoot ventilatory oscillations. Considerable evidence illustrates overlap between CSA and obstructive sleep apnoea (OSA), including elevated loop gain in patients with OSA and the presence of pharyngeal narrowing during central apnoeas...
October 31, 2016: Respirology: Official Journal of the Asian Pacific Society of Respirology
https://www.readbyqxmd.com/read/27763697/changes-in-cardiovascular-responses-to-chemoreflex-activation-of-rats-recovered-from-protein-restriction-are-not-related-to-at1-receptors
#6
Renato Willian Martins Sá, Andrea Siqueira Haibara, Paula Magalhães Gomes, Giovana Lopes Aguiar, Rafael Souza Leopoldino Nascimento, Maria Lucia Pedrosa, Andréia Carvalho Alzamora, Lisandra Brandino de Oliveira, Leonardo Máximo Cardoso
What is the central question of this study? In this study we sought to investigate whether cardiovascular responses to peripheral chemoreflex activation of rats recovered from protein restriction are related to AT1 receptors activation. What is the main finding and its importance? This study highlights the fact that angiotensinergic mechanisms activated by AT1 receptors do not supported increased responses to peripheral chemoreflex activation by KCN in rats recovered from protein restriction. Also, we found that protein restriction led to increased resting ventilation in adult rats, even after recovery...
October 20, 2016: Experimental Physiology
https://www.readbyqxmd.com/read/27756650/breath-holding-test-in-evaluation-of-peripheral-chemoreflex-sensitivity-in-healthy-subjects
#7
Nikita Trembach, Igor Zabolotskikh
: The aim of the study was to determine the feasibility of using a breath-holding test in assessing the sensitivity of the peripheral chemoreflex compared with the single-breath carbon dioxide test. The study involved 48 healthy volunteers between the ages of 18-29 years. The breath-holding test was performed followed by the single-breath carbon dioxide test on the next day. A month after the first tests, these tests were repeated to evaluate their reproducibility The coefficient of variability in the single-breath carbon dioxide test ranged from 0 to 32% with a mean of 10±7%...
January 2017: Respiratory Physiology & Neurobiology
https://www.readbyqxmd.com/read/27753889/ish-nia-os-04-p2x3-receptor-activity-in-the-carotid-body-cb-of-spontaneously-hypertensive-sh-rats-contributes-to-increased-chemoreflex-hypersensitivity-and-hypertension
#8
Wioletta Pijacka, Fiona McBryde, Anthony P Ford, Julian F R Paton
OBJECTIVE: Arterial hypertension is associated with increases in both peripheral chemoreceptor reflex sensitivity and sympathetic nerve activity (SNA). We have shown that CB resection in SH rats reduces arterial pressure (AP; McBryde et al. 2013). Since P2X3 receptors exist in the rat CB and P2X3 receptor activity is associated with afferent hyperreflexia (Ford et al. 2015), we hypothesized that P2X3 receptor would be upregulated in the CB of SH vs normotensive (Wistar) control rats and that a selective P2X3 receptor antagonist (AF-219) would reduce chemoreflex hypersensitivity, AP and SNA in SH rats...
September 2016: Journal of Hypertension
https://www.readbyqxmd.com/read/27746740/moderate-hyperbilirubinemia-alters-neonatal-cardiorespiratory-control-and-induces-inflammation-in-the-nucleus-tractus-solitarius
#9
Marie-Laure Specq, Mélisande Bourgoin-Heck, Nathalie Samson, François Corbin, Christian Gestreau, Maxime Richer, Hazim Kadhim, Jean-Paul Praud
Hyperbilirubinemia (HB) occurs in 90% of preterm newborns. Moderate HB can induce acute neurological disorders while severe HB has been linked to a higher incidence of apneas of prematurity. The present study aimed to test the hypothesis that even moderate HB disrupts cardiorespiratory control in preterm lambs. Two groups of preterm lambs (born 14 days prior to term), namely control (n = 6) and HB (n = 5), were studied. At day 5 of life, moderate HB (150-250 μmol/L) was induced during 17 h in the HB group after which cardiorespiratory control as well as laryngeal and pulmonary chemoreflexes were assessed during baseline recordings and during hypoxia...
2016: Frontiers in Physiology
https://www.readbyqxmd.com/read/27743812/mu-opioid-receptors-in-the-caudomedial-nts-are-critical-for-respiratory-responses-to-stimulation-of-bronchopulmonary-c-fibers-and-carotid-body-in-conscious-rats
#10
Jianguo Zhuang, Xiuping Gao, Franklin Gao, Fadi Xu
We tested the hypothesis that mu-opioid receptors (MORs) in the caudomedial nucleus tractus solitarius (cmNTS) are important for the ventilatory responses to stimulation of bronchopulmonary C-fibers (PCFs), the carotid body-mediated hypoxia, and hypercapnia independent of the carotid body. First, we used immunohistochemistry to map MORs distribution in the caudal medulla. Then we compared the effects of intra-cmNTS microinjection of DAMGO (a MOR agonist) with or without a combination of CTAP (a MOR antagonist) on the ventilatory responses to: 1) right atrial injection of capsaicin (to stimulation of PCFs) and 2) acute hypoxia (HVR, to stimulate the carotid body) in awake intact rats; and 3) hypercapnia (HCVR) in the carotid body ablated rats...
January 2017: Respiratory Physiology & Neurobiology
https://www.readbyqxmd.com/read/27643235/ish-nia-os-04-p2x3-receptor-activity-in-the-carotid-body-cb-of-spontaneously-hypertensive-sh-rats-contributes-to-increased-chemoreflex-hypersensitivity-and-hypertension
#11
Wioletta Pijacka, Fiona McBryde, Anthony P Ford, Julian F R Paton
OBJECTIVE: Arterial hypertension is associated with increases in both peripheral chemoreceptor reflex sensitivity and sympathetic nerve activity (SNA). We have shown that CB resection in SH rats reduces arterial pressure (AP; McBryde et al. 2013). Since P2X3 receptors exist in the rat CB and P2X3 receptor activity is associated with afferent hyperreflexia (Ford et al. 2015), we hypothesized that P2X3 receptor would be upregulated in the CB of SH vs normotensive (Wistar) control rats and that a selective P2X3 receptor antagonist (AF-219) would reduce chemoreflex hypersensitivity, AP and SNA in SH rats...
September 2016: Journal of Hypertension
https://www.readbyqxmd.com/read/27633663/impaired-central-respiratory-chemoreflex-in-an-experimental-genetic-model-of-epilepsy
#12
Leonardo T Totola, Ana C Takakura, José Antonio C Oliveira, Norberto Garcia-Cairasco, Thiago S Moreira
Respiratory disorders may involve changes in serotonergic neurotransmission at the level of the chemosensitive neurons located in the retrotrapezoid nucleus (RTN). Here, we investigated the central respiratory chemoreflex and the role of serotonergic neurotransmission in the RTN with a rat model of tonic-clonic seizures, the Wistar Audiogenic Rat (WAR). We found that naïve or kindled WAR animals have reduced resting ventilation and ventilatory response to hypercapnia (7% CO2 ). The number of chemically-coded (Phox2b(+) /TH(-) ) RTN neurons, as well as the serotonergic innervation to the RTN, was reduced in WARs...
September 16, 2016: Journal of Physiology
https://www.readbyqxmd.com/read/27626139/vagal-control-of-breathing-pattern-after-midcervical-contusion-in-rats
#13
Kun-Ze Lee, Hsiang-Chun Kuo
The present study was designed to establish a midcervical contusion model that can simulate long-term respiratory deficits, and investigate the breathing pattern during vagal-mediated respiratory reflexes following midcervical contusion. Moderate and severe (impactor height: 6.25 or 12.5 mm) contusion was induced at midline C3-4 spinal cord in adult Sprague-Dawley rats. The ventilatory behaviors of unanesthetized were evaluated by whole body plethysmography at 1 day and 1, 2, 4, and 8 weeks post-injury. The tidal volume was decreased and frequency was increased in contused animals compared with uninjured animals at the acute injury state...
October 13, 2016: Journal of Neurotrauma
https://www.readbyqxmd.com/read/27615115/quantifying-cerebrovascular-reactivity-in-anterior-and-posterior-cerebral-circulations-during-voluntary-breath-holding
#14
Christina D Bruce, Craig D Steinback, Uday V Chauhan, Jamie R Pfoh, Maria Abrosimova, Emily R Vanden Berg, Rachel J Skow, Margie H Davenport, Trevor A Day
What is the central question of this study? We developed and validated a 'stimulus index' (SI; ratio of end-tidal partial pressures of CO2 and O2 ) method to quantify cerebrovascular reactivity (CVR) in anterior and posterior cerebral circulations during breath holding. We aimed to determine whether the magnitude of CVR is correlated with breath-hold duration. What is the main finding and its importance? Using the SI method and transcranial Doppler ultrasound, we found that the magnitude of CVR of the anterior and posterior cerebral circulations is not positively correlated with physiological or psychological break-point during end-inspiratory breath holding...
December 1, 2016: Experimental Physiology
https://www.readbyqxmd.com/read/27602681/cheyne-stokes-respiration-chemoreflex-and-ticagrelor-related-dyspnea
#15
LETTER
Alberto Giannoni, Michele Emdin, Claudio Passino
No abstract text is available yet for this article.
September 8, 2016: New England Journal of Medicine
https://www.readbyqxmd.com/read/27597767/spinal-cord-injury-is-associated-with-enhanced-peripheral-chemoreflex-sensitivity
#16
Amy T Bascom, Abdulghani Sankari, M Safwan Badr
Sleep-disordered breathing (SDB) is prevalent in individuals with chronic spinal cord injury (SCI), but the exact mechanism is unknown. The aim of this study was to investigate whether peripheral chemoreceptors activity is enhanced in individuals with chronic SCI compared to abled-bodied control subjects using CO2 and O2 chemical tests. In protocol (1) 30 subjects (8 cervical [cSCI], 7 thoracic [tSCI] and 15 able-bodied [AB]) were studied to determine the ventilatory response to hyperoxia during wakefulness in the supine position...
September 2016: Physiological Reports
https://www.readbyqxmd.com/read/27595979/oxidative-stress-augments-chemoreflex-sensitivity-in-rats-exposed-to-chronic-intermittent-hypoxia
#17
Barbara J Morgan, Melissa L Bates, Rodrigo Del Rio, Zunyi Wang, John M Dopp
Chronic exposure to intermittent hypoxia (CIH) elicits plasticity of the carotid sinus and phrenic nerves via reactive oxygen species (ROS). To determine whether CIH-induced alterations in ventilation, metabolism, and heart rate are also dependent on ROS, we measured responses to acute hypoxia in conscious rats after 14 and 21 d of either CIH or normoxia (NORM), with or without concomitant administration of allopurinol (xanthine oxidase inhibitor), combined allopurinol plus losartan (angiotensin II type 1 receptor antagonist), or apocynin (NADPH oxidase inhibitor)...
December 2016: Respiratory Physiology & Neurobiology
https://www.readbyqxmd.com/read/27581562/labouring-on-decelerations-the-fetal-peripheral-chemoreflex-wins
#18
D A Giussani
No abstract text is available yet for this article.
September 1, 2016: Journal of Physiology
https://www.readbyqxmd.com/read/27573643/oxygen-sensing-mechanisms-a-physiological-penumbra
#19
Mieczyslaw Pokorski, Kotaro Takeda, Yasumasa Okada
This review tackles the unresolved issue of the existence of oxygen sensor in the body. The sensor that would respond to changes in tissue oxygen content, possibly along the hypoxia-normoxia-hyperoxia spectrum, rather than to a given level of oxygen, and would translate the response into lung ventilation changes, the major adaptive process. Studies on oxygen sensing, for decades, concentrated around the hypoxic ventilatory response generated mostly by carotid body chemoreceptor cells. Despite gaining a substantial insight into the cellular transduction pathways in carotid chemoreceptors, the exact molecular mechanisms of the chemoreflex have never been conclusively verified...
August 30, 2016: Advances in Experimental Medicine and Biology
https://www.readbyqxmd.com/read/27559818/resonance-as-the-mechanism-of-daytime-periodic-breathing-in-patients-with-heart-failure
#20
Scott A Sands, Yoseph Mebrate, Bradley A Edwards, Shamim Nemati, Charlotte H Manisty, Akshay S Desai, Andrew Wellman, Keith Willson, Darrel P Francis, James P Butler, Atul Malhotra
RATIONALE: In patients with chronic heart failure, daytime oscillatory breathing at rest is associated with high mortality risk. Experimental evidence, including exaggerated ventilatory responses to carbon dioxide (CO2) and prolonged circulation time, implicates the ventilatory control system and suggests feedback instability (loop gain>1) is responsible. However, daytime oscillatory patterns often appear remarkably irregular versus classical instability (Cheyne-Stokes respiration), suggesting our mechanistic understanding is limited...
August 25, 2016: American Journal of Respiratory and Critical Care Medicine
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