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Chemoreflex

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https://www.readbyqxmd.com/read/28808320/carotid-body-mediated-chemoreflex-drive-in-the-setting-of-low-and-high-output-heart-failure
#1
Rodrigo Del Rio, David C Andrade, Camilo Toledo, Hugo S Diaz, Claudia Lucero, Alexis Arce-Alvarez, Noah J Marcus, Harold D Schultz
Enhanced carotid body (CB) chemoreflex function is strongly related to cardiorespiratory disorders and disease progression in heart failure (HF). The mechanisms underlying CB sensitization during HF are not fully understood, however previous work indicates blood flow per se can affect CB function. Then, we hypothesized that the CB-mediated chemoreflex drive will be enhanced only in low output HF but not in high output HF. Myocardial infarcted rats and aorto-caval fistulated rats were used as a low output HF model (MI-CHF) and as a high output HF model (AV-CHF), respectively...
August 14, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28757365/assessing-chemoreflexes-and-oxygenation-in-the-context-of-acute-hypoxia-implications-for-field-studies
#2
Jamie R Pfoh, Craig D Steinback, Emily R Vanden Berg, Christina D Bruce, Trevor A Day
Carotid chemoreceptors detect changes in PO2 and elicit a peripheral respiratory chemoreflex (PCR). The PCR can be tested through a transient hypoxic ventilatory response test (TT-HVR), which may not be safe nor feasible at altitude. We characterized a transient hyperoxic ventilatory withdrawal test in the setting of steady-state normobaric hypoxia (13.5-14% FIO2) and compared it to a TT-HVR and a steady-state poikilocapnic hypoxia test, within-individuals. No PCR test magnitude was correlated with any other test, nor was any test magnitude correlated with oxygenation while in steady-state hypoxia...
July 27, 2017: Respiratory Physiology & Neurobiology
https://www.readbyqxmd.com/read/28740186/carotid-sinus-nerve-electrical-stimulation-in-conscious-rats-attenuates-systemic-inflammation-via-chemoreceptor-activation
#3
Fernanda Machado Santos-Almeida, Gean Domingos-Souza, César A Meschiari, Laura Campos Fávaro, Christiane Becari, Jaci A Castania, Alexandre Lopes, Thiago M Cunha, Davi J A Moraes, Fernando Q Cunha, Luis Ulloa, Alexandre Kanashiro, Geisa C S V Tezini, Helio C Salgado
Recent studies demonstrated a critical functional connection between the autonomic (sympathetic and parasympathetic) nervous and the immune systems. The carotid sinus nerve (CSN) conveys electrical signals from the chemoreceptors of the carotid bifurcation to the central nervous system where the stimuli are processed to activate sympathetic and parasympathetic efferent signals. Here, we reported that chemoreflex activation via electrical CSN stimulation, in conscious rats, controls the innate immune response to lipopolysaccharide attenuating the plasma levels of inflammatory cytokines such as tumor necrosis factor (TNF), interleukin 1β (IL-1β) and interleukin 6 (IL-6)...
July 24, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28677303/glial-eaat2-regulation-of-extracellular-nts-glutamate-critically-controls-neuronal-activity-and-cardiorespiratory-reflexes
#4
Michael P Matott, David D Kline, Eileen M Hasser
Glutamatergic signalling is critical in the nucleus tractus solitarii (nTS) for cardiorespiratory homeostasis and initiation of sensory reflexes, including the chemoreflex activated during hypoxia. Maintenance of nTS glutamate concentration occurs in part through astrocytic excitatory amino acid transporters (EAATs). We previously established the importance of EAATs in the nTS by demonstrating their inhibition produced neuronal excitation to alter basal cardiorespiratory function. Since EAAT2 is the most expressed EAAT in the nTS, this study specifically determined EAAT2's role in nTS astrocytes, their influence on neuronal and synaptic properties, and ultimately on basal and reflex cardiorespiratory function...
July 5, 2017: Journal of Physiology
https://www.readbyqxmd.com/read/28675564/activation-of-serotonergic-neurons-in-the-medullary-caudal-raphe-shortens-the-laryngeal-chemoreflex-in-anaesthetized-neonatal-rats
#5
William T Donnelly, Luxi Xia, Donald Bartlett, J C Leiter
What is the central question of this study? Does activation of serotonergic neurons in the caudal medullary raphe, some of which project to the nucleus of the solitary tract, shorten the laryngeal chemoreflex? What is the main finding and its importance? We found that serotonin originating from neurons in the caudal raphe acts through a 5-HT3 receptor located in the nucleus of the solitary tract to terminate reflex apnoea. Failure or deficiency of this arousal-related process is likely to be relevant to the pathogenesis of sudden infant death syndrome...
July 3, 2017: Experimental Physiology
https://www.readbyqxmd.com/read/28666602/integrated-cardiovascular-respiratory-control-in-type-1-diabetes-evidences-functional-imbalance-possible-role-of-hypoxia
#6
L Bianchi, C Porta, A Rinaldi, C Gazzaruso, P Fratino, P DeCata, P Protti, R Paltro, L Bernardi
BACKGROUND: Cardiovascular (baroreflex) and respiratory (chemoreflex) control mechanisms were studied separately in diabetes, but their reciprocal interaction (well known for diseases like heart failure) had never been comprehensively assessed. We hypothesized that prevalent autonomic neuropathy would depress both reflexes, whereas prevalent autonomic imbalance through sympathetic activation would depress the baroreflex but enhance the chemoreflexes. METHODS: In 46 type-1 diabetic subjects (7...
June 15, 2017: International Journal of Cardiology
https://www.readbyqxmd.com/read/28659824/hypersensitivity-of-vagal-pulmonary-afferents-induced-by-tumor-necrosis-factor-alpha-in-mice
#7
Ruei-Lung Lin, Qihai Gu, Lu-Yuan Lee
Tumor necrosis factor alpha (TNFα), a pro-inflammatory cytokine, plays a significant role in the pathogenesis of allergic asthma. Inhalation of TNFα also induces airway hyperresponsiveness in healthy human subjects, and the underlying mechanism is not fully understood. A recent study reported that TNFα caused airway inflammation and a sustained elevation of pulmonary chemoreflex responses in mice, suggesting a possible involvement of heightened sensitivity of vagal pulmonary C-fibers. To investigate this possibility, the present study aimed to investigate the effect of a pretreatment with TNFα on the sensitivity of vagal pulmonary afferents in anesthetized mice...
2017: Frontiers in Physiology
https://www.readbyqxmd.com/read/28650915/the-brainstem-network-controlling-blood-pressure-an-important-role-for-pressor-sites-in-the-caudal-medulla-and-cervical-spinal-cord
#8
Michael G Z Ghali
: Although medullary control of blood pressure (BP) has been extensively studied, the contribution of critical regions, such as pressor sites in the caudal medulla and upper cervical spinal cord and the lateral tegmental field, remains controversial and underappreciated. A series of pressor sites caudal to the caudal ventrolateral medulla (CVLM), including the caudal pressor area (CPA) and medullocervical pressor area, play an important role in control of BP. Activation and inhibition of these sites elicits pressor and depressor responses, respectively...
June 24, 2017: Journal of Hypertension
https://www.readbyqxmd.com/read/28640969/control-of-breathing-and-ventilatory-acclimatization-to-hypoxia-in-deer-mice-native-to-high-altitudes
#9
Catherine M Ivy, Graham R Scott
AIM: We compared the control of breathing and heart rate by hypoxia between high- and low-altitude populations of Peromyscus mice, to help elucidate the physiological specializations that help high-altitude natives cope with O2 limitation. METHODS: Deer mice (P. maniculatus) native to high altitude and congeneric mice native to low altitude (P. leucopus) were bred in captivity at sea level. The F1 progeny of each population were raised to adulthood and then acclimated to normoxia or hypobaric hypoxia (12 kPa, simulating hypoxia at ~4300 m) for 5 months...
June 22, 2017: Acta Physiologica
https://www.readbyqxmd.com/read/28637679/characterization-of-ectonucleotidase-expression-in-the-rat-carotid-body-regulation-by-chronic-hypoxia
#10
Shaima Salman, Cathy Vollmer, Grant B McClelland, Colin A Nurse
The carotid body (CB) chemoreflex maintains blood PO2 and PCO2/H(+) homeostasis and displays sensory plasticity during exposure to chronic hypoxia. Purinergic signaling via P1 and P2 receptors plays a pivotal role in shaping the afferent discharge at the sensory synapse containing catecholaminergic chemoreceptor (type I) cells, glial-like type II cells, and sensory (petrosal) nerve endings. However, little is known about the family of ectonucleotidases that control synaptic nucleotide levels. Using quantitative PCR (QPCR), we first compared expression levels of ectonucleoside triphosphate diphosphohydrolases (NTPDases1,2,3,5,6) and ecto-5'-nucleotidase (E5'Nt/CD73) mRNAs in juvenile rat CB versus brain, petrosal ganglia, sympathetic (superior cervical) ganglia, and a sympathoadrenal chromaffin (MAH) cell line...
June 21, 2017: American Journal of Physiology. Cell Physiology
https://www.readbyqxmd.com/read/28620058/intermittent-hypercapnic-hypoxia-during-sleep-does-not-induce-ventilatory-long-term-facilitation-in-healthy-males
#11
Naomi Louise Deacon, Doug R McEvoy, Daniel L Stadler, Peter G Catcheside
Intermittent hypoxia induced ventilatory neuroplasticity is likely important in obstructive sleep apnea pathophysiology. Although concomitant CO2 levels and arousal state critically influence neuroplastic effects of intermittent hypoxia, no studies have investigated intermittent hypercapnic hypoxia effects during sleep in humans. Thus, the purpose of this study was to investigate if intermittent hypercapnic hypoxia during sleep induces neuroplasticity (ventilatory long-term facilitation and increased chemoreflex responsiveness) in humans...
June 15, 2017: Journal of Applied Physiology
https://www.readbyqxmd.com/read/28476501/norepinephrine-stimulation-of-alpha1d-adrenoceptor-promotes-proliferation-of-pulmonary-artery-smooth-muscle-cells-via-erk-1-2-signaling
#12
Ruxia Liu, Qianlong Zhang, Qian Luo, Hui Qiao, Peng Wang, Juan Yu, Yonggang Cao, Bo Lu, Lihui Qu
It has been shown that the sympathetic nervous system is activated in pulmonary arterial hypertension (PAH). Norepinephrine (NE) levels are increased by chemoreflex-dependent sympathetic overactivation and involved in pulmonary vascular remodeling. However, the underlying mechanisms of the remodeling induced by NE are poorly understood. In this study, we found that, in vivo, the expression of tyrosine hydroxylase and the concentration of plasma NE were increased in PAH rats compared with normal rats. Increases in ventricular hypertrophy and medial width of the pulmonary arteries were reversed by prazosin, α1-adrenoceptor (α1-AR) antagonists, in PAH rats...
July 2017: International Journal of Biochemistry & Cell Biology
https://www.readbyqxmd.com/read/28461215/role-of-a5-noradrenergic-neurons-in-the-chemoreflex-control-of-respiratory-and-sympathetic-activities-in-unanesthetized-conditions
#13
Camila L Taxini, Thiago S Moreira, Ana C Takakura, Kênia C Bícego, Luciane H Gargaglioni, Daniel B Zoccal
The A5 area at the ventrolateral pons contains noradrenergic neurons connected with other medullary areas involved in the cardiorespiratory control. Its contribution to the cardiorespiratory regulation was previously evidenced in anesthetized conditions. In the present study, we investigated the involvement of the A5 noradrenergic neurons to the basal and chemoreflex control of the sympathetic and respiratory activities in unanesthetized conditions. A5 noradrenergic neurons were lesioned using microinjections of anti-dopamine β-hydroxylase saporin (anti-DβH-SAP)...
April 29, 2017: Neuroscience
https://www.readbyqxmd.com/read/28451849/role-of-carotid-body-in-intermittent-hypoxia-related-hypertension
#14
REVIEW
Rodrigo Iturriaga, María Paz Oyarce, Ana Carolina Rodrigues Dias
Obstructive sleep apnea (OSA), a common breathing disorder, is recognized as an independent risk factor for systemic hypertension. Among the alterations induced by OSA, the chronic intermittent hypoxia (CIH) is considered the main factor for the hypertension. Exposure of rodents to CIH is the gold-standard method to study the mechanisms involved in the cardiovascular alterations induced by OSA. Although it is well known that CIH produces hypertension, the underlying mechanisms are not totally elucidated. It is likely that the CIH-induced systemic oxidative stress and inflammation may elicit endothelial dysfunction and increase the arterial blood pressure...
May 2017: Current Hypertension Reports
https://www.readbyqxmd.com/read/28416458/on-the-origins-of-sex-based-differences-in-respiratory-disorders-lessons-and-hypotheses-from-stress-neuroendocrinology-in-developing-rats
#15
REVIEW
Jean-Philippe Rousseau, Luana Tenorio-Lopes, Cécile Baldy, Tara Adele Janes, Stéphanie Fournier, Richard Kinkead
The environment plays a critical role in shaping development and function of the brain. Stress, especially when experienced early in life, can interfere with these processes. In the context of respiratory control, perinatal stress can therefore alter the ability to achieve the "fine-tuning" necessary for proper detection of chemosensory stimuli and production of an adequate motor (respiratory) command. Depending on the timing, intensity, and duration, the detrimental consequences of perinatal exposure to adverse conditions on the respiratory network become manifest at various life stages and can persist into adulthood...
April 14, 2017: Respiratory Physiology & Neurobiology
https://www.readbyqxmd.com/read/28404583/acute-hypoxia-activates-neuroendocrine-but-not-presympathetic-neurons-in-the-paraventricular-nucleus-of-the-hypothalamus-differential-role-of-nitric-oxide
#16
K Max Coldren, De-Pei Li, David D Kline, Eileen M Hasser, Cheryl M Heesch
Hypoxia results in decreased arterial Po2, arterial chemoreflex activation, and compensatory increases in breathing, sympathetic outflow, and neuroendocrine secretions, including increased secretion of AVP, corticotropin-releasing hormone (CRH), adrenocorticotropin hormone (ACTH), and corticosterone. In addition to a brain stem pathway, including the nucleus tractus solitarius (nTS) and the rostral ventrolateral medulla (RVLM), medullary pathways to the paraventricular nucleus of the hypothalamus (PVN) contribute to chemoreflex responses...
June 1, 2017: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/28343606/respiratory-muscles-and-chemoreflex-sensitivity-in-heart-failure-a-breath-of-fresh-air
#17
EDITORIAL
Richard Severin, Shane A Phillips
No abstract text is available yet for this article.
April 2017: Canadian Journal of Cardiology
https://www.readbyqxmd.com/read/28323007/inhibition-of-microglial-activation-with-minocycline-at-the-intrathecal-level-attenuates-sympathoexcitatory-and-proarrhythmogenic-changes-in-rats-with-chronic-temporal-lobe-epilepsy
#18
Amol M Bhandare, Komal Kapoor, Kim L Powell, Emma Braine, Pablo Casillas-Espinosa, Terence J O'Brien, Melissa M J Farnham, Paul M Pilowsky
The incidence of sudden unexpected death in epilepsy (SUDEP) is highest in people with chronic and drug-resistant epilepsy. Chronic spontaneous recurrent seizures cause cardiorespiratory autonomic dysfunctions. Pituitary adenylate cyclase-activating polypeptide (PACAP) is neuroprotective, whereas microglia produce both pro- and anti-inflammatory effects in the CNS. During acute seizures in rats, PACAP and microglia produce sympathoprotective effect at the intermediolateral cell column (IML), whereas their action on the presympathetic rostral ventrolateral medulla (RVLM) neurons mediates proarrhythmogenic changes...
March 18, 2017: Neuroscience
https://www.readbyqxmd.com/read/28288844/forced-vital-capacity-and-not-central-chemoreflex-predicts-maximal-hyperoxic-breath-hold-duration-in-elite-apneists
#19
Anthony R Bain, Otto F Barak, Ryan L Hoiland, Ivan Drvis, Damian M Bailey, Zeljko Dujic, Tanja Mijacika, Antoinette Santoro, Daniel K DeMasi, David B MacLeod, Philip N Ainslie
The determining mechanisms of a maximal hyperoxic apnea duration in elite apneists have remained unexplored. We tested the hypothesis that maximal hyperoxic apnea duration in elite apneists is related to forced vital capacity (FVC) but not the central chemoreflex (for CO2). Eleven elite apneists performed a maximal dry static-apnea with prior hyperoxic (100% oxygen) pre-breathing, and a central chemoreflex test via a hyperoxic re-breathing technique (hyperoxic-hypercapnic ventilatory response: HCVR); expressed as the increase in ventilation (pneumotachometry) per increase in arterial CO2 tension (PaCO2; radial artery)...
March 11, 2017: Respiratory Physiology & Neurobiology
https://www.readbyqxmd.com/read/28279732/intra-individual-variability-in-cerebrovascular-and-respiratory-chemosensitivity-can-we-characterize-a-chemoreflex-reactivity-profile
#20
Kennedy J Borle, Jamie R Pfoh, Lindsey M Boulet, Maria Abrosimova, Michael M Tymko, Rachel J Skow, Amy Varner, Trevor A Day
Intra-individual variability in the magnitude of human cerebrovascular and respiratory chemoreflex responses is largely unexplored. By comparing response magnitudes of cerebrovascular CO2 reactivity (CVR; middle and posterior cerebral arteries; MCA, PCA), central (CCR; CO2) and peripheral respiratory chemoreflexes (PCR; CO2 and O2), we tested the hypothesis that a within-individual reactivity magnitude profile could be characterized. The magnitudes of CVR and CCR were tested with hyperoxic rebreathing and PCR magnitudes were tested through transient respiratory tests (TT-CO2, hypercapnia; TT-N2, hypoxia)...
March 6, 2017: Respiratory Physiology & Neurobiology
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