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Chemoreflex

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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
#1
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
#2
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
#3
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
#4
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
#5
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...
May 2, 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
#6
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
#7
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
#8
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-pre-sympathetic-neurons-in-the-paraventricular-nucleus-of-the-hypothalamus-differential-role-of-nitric-oxide
#9
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 vasopressin (AVP), corticotropin releasing hormone (CRH), adrenocorticotropin hormone (ACTH), and corticosterone. In addition to a brainstem 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...
April 12, 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
#10
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
#11
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
#12
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
#13
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
https://www.readbyqxmd.com/read/28251147/the-influence-of-age-on-interaction-between-breath-holding-test-and-single-breath-carbon-dioxide-test
#14
Nikita Trembach, Igor Zabolotskikh
Introduction. The aim of the study was to compare the breath-holding test and single-breath carbon dioxide test in evaluation of the peripheral chemoreflex sensitivity to carbon dioxide in healthy subjects of different age. Methods. The study involved 47 healthy volunteers between ages of 25 and 85 years. All participants were divided into 4 groups according to age: 25 to 44 years (n = 14), 45 to 60 years (n = 13), 60 to 75 years (n = 12), and older than 75 years (n = 8). Breath-holding test was performed in the morning before breakfast...
2017: BioMed Research International
https://www.readbyqxmd.com/read/28215596/sex-specific-respiratory-effects-of-acute-and-chronic-caffeine-administration-in-newborn-rats
#15
REVIEW
Hayet Kouchi, NagaPraveena Uppari, Vincent Joseph, Aida Bairam
Caffeine is widely used for the treatment of apnea of prematurity (AoP) but whether this effect varies with sex is unknown. To shed some light on this question, we present a summary of data obtained on the effects of caffeine on the respiratory chemoreflexes and apnea frequency in 1- and 12-days old male and female rats. Caffeine was either administered as a single acute injection (10mg/kg, i.p.) or for 10 consecutive days (7.5mg/kg/day between 3 and 12days of life by gavage, simulating its clinical use). Acute caffeine had little effects on breathing in 1-day old male and female rats...
June 2017: Respiratory Physiology & Neurobiology
https://www.readbyqxmd.com/read/28188852/the-k%C3%A3-lliker-fuse-nucleus-acts-as-a-timekeeper-for-late-expiratory-abdominal-activity
#16
Sarah E M Jenkin, William K Milsom, Daniel B Zoccal
While the transition from the inspiratory to the post-inspiratory (post-I) phase is dependent on the pons, little attention has been paid to understanding the role of the pontine respiratory nuclei, specifically the Kölliker-Fuse nucleus (KF), in transitioning from post-I to the late expiratory (late-E) activity seen with elevated respiratory drive. To elucidate this, we used the in situ working heart-brainstem preparation of juvenile male Holtzman rats and recorded from the vagus (cVN), phrenic (PN) and abdominal nerves (AbN) during baseline conditions and during chemoreflex activation [with potassium cyanide (KCN; n=13) or hypercapnia (8% CO2; n=10)] to recruit active expiration...
February 8, 2017: Neuroscience
https://www.readbyqxmd.com/read/28181258/cardiac-diastolic-and-autonomic-dysfunction-are-aggravated-by-central-chemoreflex-activation-in-heart-failure-with-preserved-ejection-fraction-rats
#17
Camilo Toledo, David C Andrade, Claudia Lucero, Alexis Arce-Alvarez, Hugo S Díaz, Valentín Aliaga, Harold D Schultz, Noah J Marcus, Mónica Manríquez, Marcelo Faúndez, Rodrigo Del Rio
KEY POINTS: Heart failure with preserved ejection fraction (HFpEF) is associated with disordered breathing patterns, and sympatho-vagal imbalance. Although it is well accepted that altered peripheral chemoreflex control plays a role in the progression of heart failure with reduced ejection fraction (HFrEF), the pathophysiological mechanisms underlying deterioration of cardiac function in HFpEF are poorly understood. We found that central chemoreflex is enhanced in HFpEF and neuronal activation is increased in pre-sympathetic regions of the brainstem...
April 15, 2017: Journal of Physiology
https://www.readbyqxmd.com/read/28177673/interleukin-1beta-suppresses-the-ventilatory-hypoxic-response-in-rats-via-prostaglandin-dependent-pathways
#18
Nina P Aleksandrova, Galina A Danilova, Viacheslav G Aleksandrov
We investigated the effect of the major inflammatory cytokine interleukin-1beta (IL-1β) on the ventilatory response to hypoxia. The goal was to test the hypothesis that IL-1β impairs the hypoxic ventilatory response in vivo by indirectly inhibiting respiratory neurons in the brainstem via prostaglandins. Thus, IL-1β was delivered by cerebroventricular injection, and the ventilatory hypoxic response was assessed in anesthetized, spontaneously breathing rats pretreated with or without diclofenac, a nonspecific inhibitor of prostaglandin synthesis...
January 22, 2017: Canadian Journal of Physiology and Pharmacology
https://www.readbyqxmd.com/read/28132741/respiratory-muscle-training-improves-chemoreflex-response-heart-rate-variability-and-respiratory-mechanics-in-rats-with-heart-failure
#19
Rodrigo B Jaenisch, Edson Quagliotto, Chalyne Chechi, Leonardo Calegari, Fernando Dos Santos, Audrey Borghi-Silva, Pedro Dal Lago
BACKGROUND: The aim of the present report was to evaluate respiratory muscle training (RMT) effects on hemodynamic function, chemoreflex response, heart rate variability, and respiratory mechanics in rats with heart failure (HF rats). METHODS: Wistar rats were divided into 4 groups: sedentary-sham (Sed-Sham, n = 8), respiratory muscle trained-sham (RMT-Sham, n = 8), sedentary-HF (Sed-HF, n = 8) and respiratory muscle trained-HF (RMT-HF, n = 8). Animals were submitted to an RMT protocol performed 30 minutes per day, 5 days per week for 6 weeks, whereas the sedentary animals did not exercise...
April 2017: Canadian Journal of Cardiology
https://www.readbyqxmd.com/read/28106557/blunted-respiratory-responses-in%C3%A2-the%C3%A2-streptozotocin-induced-alzheimer-s-disease-rat-model
#20
Dalton L Ebel, Christopher G Torkilsen, Tim D Ostrowski
Alzheimer's disease (AD) is known for the progressive decline of cognition and memory. In addition to these disease-defining symptoms, impairment of respiratory function is frequently observed and often expressed by sleep-disordered breathing or reduced ability to adjust respiration when oxygen demand is elevated. The mechanisms for this are widely unknown. Postmortem analysis from the brainstem of AD patients reveals pathological alterations, including in nuclei responsible for respiratory control. In this study, we analyzed respiratory responses and morphological changes in brainstem nuclei following intracerebroventricular (ICV) injections of streptozotocin (STZ), a rat model commonly used to mimic sporadic AD...
January 20, 2017: Journal of Alzheimer's Disease: JAD
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