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https://www.readbyqxmd.com/read/29789952/carotid-body-ablation-a-new-target-to-address-central-autonomic-dysfunction
#1
REVIEW
Rodrigo Iturriaga
PURPOSE OF REVIEW: An abnormal heightened carotid body (CB) chemoreflex, which produces autonomic dysfunction and sympathetic overactivation, is the common hallmark of obstructive sleep apnea (OSA), resistant hypertension, systolic heart failure (HF), and cardiometabolic diseases. Accordingly, it has been proposed that the elimination of the CB chemosensory input to the brainstem may reduce the autonomic and cardiorespiratory alterations in sympathetic-associated diseases in humans. RECENT FINDINGS: A growing body of evidence obtained in preclinical animal models support that an enhanced CB discharge produces sympathetic hyperactivity, baroreflex sensitivity and heart rate variability impairment, breathing instability, hypertension, and insulin resistance...
May 22, 2018: Current Hypertension Reports
https://www.readbyqxmd.com/read/29775659/%C3%AE-2-receptors-in-the-lateral-parabrachial-nucleus-generates-the-pressor-response-of-the-cardiovascular-chemoreflex-effects-of-gaba-a-receptor
#2
Nafiseh Mirzaei Damabi, Gholam Reza Namvar, Fahimeh Yeganeh, Masoumeh Hatam
The lateral parabrachial nucleus (LPBN) is a pontine area involved in cardiovascular chemoreflex. This study was performed to find the effects of reversible synaptic blockade of the LPBN on the chemoreflex responses, and to find the roles of GABAA receptor and α2 -adenoreceptor (α2 -AR) in chemoreflex. It also aimed to seek possible interaction between GABA and noradrenergic systems of the LPBN in urethane-anesthetized male rats. Cardiovascular chemoreflex was activated by intravenous injection of potassium cyanide (KCN, 80 μg/kg)...
May 15, 2018: Brain Research Bulletin
https://www.readbyqxmd.com/read/29751145/antioxidant-treatment-for-impaired-hypoxic-ventilatory-responses-in-experimental-diabetes-in-the-rat
#3
Mieczyslaw Pokorski, Malgorzata Poździk, Andrea Mazzatenta
Inflammation, tissue hypoxia, and impaired hypoxic ventilatory response (HVR) are the intricately entwined features of diabetes which perpetuate the disease and its sequelae. Hyperglycemia, notably, is an oxygen consuming process due to enhanced cellular metabolism. Oxidative stress underlies diabetic pathogenesis and also is a crucial modulator of the hypoxic chemoreflex. The present study seeks to determine if suppressed ventilation in diabetes could be improved by antioxidant treatment. The study was performed in streptozotocin-induced diabetes in awake rats...
May 8, 2018: Respiratory Physiology & Neurobiology
https://www.readbyqxmd.com/read/29750475/effects-of-losartan-and-allopurinol-on-cardiorespiratory-regulation-in-obstructive-sleep-apnoea
#4
Barbara J Morgan, Mihaela Teodorescu, David F Pegelow, Emily R Jackson, Devin L Schneider, David T Plante, James P Gapinski, Scott J Hetzel, John M Dopp
Chemoreflex sensitization produced by chronic intermittent hypoxia (CIH) in rats is attenuated by angiotensin II type 1 receptor (AT1 R) blockade. AT1 R blockade and xanthine oxidase inhibition both ameliorate CIH-induced endothelial dysfunction. We hypothesized treatment with losartan and allopurinol would reduce chemoreflex sensitivity and improve hypoxic vasodilation in patients with obstructive sleep apnoea (OSA). Eighty-six hypertensive patients with apnoea-hypopnoea index ≥25 events/hr and no other cardiovascular, pulmonary, renal, or metabolic disease were randomly assigned to receive allopurinol, losartan, or placebo for 6 weeks...
May 11, 2018: Experimental Physiology
https://www.readbyqxmd.com/read/29723577/ampa-receptor-dependent-glutamatergic-signaling-is-present-in-the-carotid-chemoreceptor
#5
Yuzhen Liu, Chaohong Li, Xianglei Jia, Lu Huang, J Woodrow Weiss
Exposure to both sustained and intermittent hypoxia for as little as a day produces sustained augmentation of carotid chemoreceptor sensitivity; however, the molecular basis for this chemoreflex plasticity remains uncertain. We previously reported that NMDA receptor dependent glutamatergic signaling in rat carotid body played a role in altered hypoxic sensitivity after exposure to cyclic intermittent hypoxia (CIH). Here we found that mRNAs of multiple AMPA and Kainate glutamate receptors were expressed in rat carotid body...
April 30, 2018: Neuroscience
https://www.readbyqxmd.com/read/29713356/sudden-unexpected-cardio-respiratory-arrest-after-venipuncture-in-children
#6
Goun Jeong, Son Moon Shin, Nam Su Kim, Young Min Ahn
Purpose: This study aimed to investigate the clinical and socioenvironmental characteristics of sudden cardiorespiratory arrest after venipuncture in children. Methods: We conducted a retrospective email-based survey of all members of the Korean Pediatric Society. The questionnaire included items on patient demographics, socioenvironmental circumstances of the venipuncture, type of cardiorespiratory arrest, symptoms and signs, treatment, prognosis, and presumed cause of the arrest...
April 2018: Korean Journal of Pediatrics
https://www.readbyqxmd.com/read/29701248/carotid-body-activity-are-we-eating-our-way-into-the-ventilatory-pathway
#7
Hannah Leverton, Cailey England, Ashtyn Baxandall
Maintenance of the partial pressure of arterial O2 and CO2 blood gases (PaO2 and PaCO2 , respectively) is coordinated through two distinct, but interacting chemoreflex feedback loops. This article is protected by copyright. All rights reserved.
April 27, 2018: Journal of Physiology
https://www.readbyqxmd.com/read/29667182/breathing-regulation-and-blood-gas-homeostasis-after-near-complete-lesions-of-the-retrotrapezoid-nucleus-in-adult-rats
#8
George M P R Souza, Roy Kanbar, Daniel S Stornetta, Stephen B G Abbott, Ruth L Stornetta, Patrice G Guyenet
The retrotrapezoid nucleus (RTN) is one of several CNS nuclei that contribute, in various capacities (e.g. CO2 detection, neuronal modulation) to the central respiratory chemoreflex (CRC). Here we test how important the RTN is to PCO2 homeostasis and breathing during sleep or wake. RTN Nmb positive neurons were killed with targeted microinjections of substance-P-saporin conjugate in adult rats. Under normoxia, rats with large RTN lesions (92 ± 4 % cell loss) had normal blood pressure (BP) and arterial pH but were hypoxic (-8 mmHg PaO2 ) and hypercapnic (+10 mmHg PaCO2 )...
April 18, 2018: Journal of Physiology
https://www.readbyqxmd.com/read/29645283/sympathoexcitation-following-intermittent-hypoxia-in-rat-is-mediated-by-circulating-angiotensin-ii-acting-at-the-carotid-body-and-subfornical-organ
#9
Seung Jae Kim, Angelina Y Fong, Paul M Pilowsky, Stephen B G Abbott
Circulating angiotensin II (AngII) is vital for arterial pressure elevation following intermittent hypoxia in rats, but its importance in the induction of sympathetic changes is unclear. We tested the contribution of the RAS to the effects of acute intermittent hypoxia (AIH) in anaesthetized ventilated adult rats. AIH caused a 33.7 ± 2.9% increase in sympathetic nerve activity (SNA), and a one-fold increase in sympathetic peripheral chemoreflex sensitivity and central sympathetic-respiratory coupling. The sympathetic effects of AIH were prevented by blocking angiotensin type 1 receptors with systemic losartan and intermittent systemic injections of AngII (Int...
April 12, 2018: Journal of Physiology
https://www.readbyqxmd.com/read/29604081/the-peripheral-chemoreflex-indefatigable-guardian-of-fetal-physiological-adaptation-to-labour
#10
Christopher A Lear, Guido Wassink, Jenny A Westgate, Jan G Nijhuis, Austin Ugwumadu, Robert Galinsky, Laura Bennet, Alistair J Gunn
The fetus is consistently exposed to repeated periods of impaired oxygen (hypoxaemia) and nutrient supply in labour. This is balanced by the healthy fetus's remarkable anaerobic tolerance, and impressive ability to mount protective adaptations to hypoxaemia. The most important mediator of fetal adaptations to brief repeated hypoxaemia is the peripheral chemoreflex, a rapid reflex response to acute falls in arterial oxygen tension. The overwhelming majority of fetuses are able to respond to repeated uterine contractions without developing hypotension or hypoxic-ischaemic injury...
March 31, 2018: Journal of Physiology
https://www.readbyqxmd.com/read/29565769/hyperadditive-ventilatory-response-arising-from-interaction-between-the-carotid-chemoreflex-and-the-muscle-mechanoreflex-in-healthy-humans
#11
Talita M Silva, Liliane C Aranda, Marcelle Paula-Ribeiro, Diogo M Oliveira, Wladimir Musetti Medeiros, Lauro C Vianna, Luiz E Nery, Bruno M Silva
Physical exercise potentiates the carotid chemoreflex control of ventilation (VE). Hyperadditive neural interactions may partially mediate the potentiation. However, some neural interactions remain incompletely explored. As the potentiation occurs even during low-intensity exercise, we tested the hypothesis that the carotid chemoreflex and the muscle mechanoreflex could interact in a hyperadditive fashion. Fourteen young healthy subjects inhaled, randomly, in separate visits, 12% O2 to stimulate the carotid chemoreflex, and 21% O2 as control...
March 22, 2018: Journal of Applied Physiology
https://www.readbyqxmd.com/read/29561178/effect-of-chronic-intermittent-hypoxia-on-angiotensin-ii-receptors-in-the-central-nervous-system
#12
Barbara J Morgan, Nicole Schrimpf, Morgan Rothman, Ann Mitzey, Mark S Brownfield, Robert C Speth, John M Dopp
Chronic intermittent hypoxia (CIH) increases basal sympathetic nervous system activity, augments chemoreflex-induced sympathoexcitation, and raises blood pressure. All effects are attenuated by systemic or intracerebroventricular administration of angiotensin II type 1 receptor (AT1 R) antagonists. This study aimed to quantify the effects of CIH on AT1 R- and AT2 R-like immunoreactivity in the rostroventrolateral medulla (RVLM) and paraventricular nucleus of the hypothalamus (PVN), central regions that are important components of the extended chemoreflex pathway...
March 21, 2018: Clinical and Experimental Hypertension: CHE
https://www.readbyqxmd.com/read/29511418/obstetrics-at-decisive-crossroads-regarding-pattern-recognition-of-fetal-heart-rate-decelerations-scientific-principles-and-lessons-from-memetics
#13
REVIEW
Shashikant L Sholapurkar
The survival of cardiotocography (CTG) as a tool for intrapartum fetal monitoring seems threatened somewhat unjustifiably and unwittingly despite the absence of better alternatives. Fetal heart rate (FHR) decelerations are center-stage (most important) in the interpretation of CTG with maximum impact on three-tier classification. The pattern-discrimination of FHR decelerations is inexorably linked to their nomenclature. Unscientific or flawed nomenclature of decelerations can explain the dysfunctional CTG interpretation leading to errors in detection of acidemic fetuses...
April 2018: Journal of Clinical Medicine Research
https://www.readbyqxmd.com/read/29509982/development-of-an-anaesthetized-rat-model-of-exercise-hyperpnoea-an-integrative-model-of-respiratory-control-using-an-equilibrium-diagram
#14
Tadayoshi Miyamoto, Kou Manabe, Shinya Ueda, Hidehiro Nakahara
NEW FINDINGS: What is the central question of this study? The lack of useful small-animal models for studying exercise hyperpnoea makes it difficult to investigate the underlying mechanisms of exercise-induced ventilatory abnormalities in various disease states. What is the main finding and its importance? We developed an anaesthetized-rat model for studying exercise hyperpnoea, using a respiratory equilibrium diagram for quantitative characterization of the respiratory chemoreflex feedback system...
May 1, 2018: Experimental Physiology
https://www.readbyqxmd.com/read/29471072/neuroreflex-control-of-cardiovascular-function-is-impaired-after-acute-poisoning-with-chlorpyrifos-an-organophosphorus-insecticide-possible-short-and-long-term-clinical-implications
#15
Alexandre F Cunha, Igor S A Felippe, Nilson C Ferreira-Junior, Leonardo B M Resstel, Daniela A M Guimarães, Vanessa Beijamini, Julian F R Paton, Karla N Sampaio
Although it is well-established that severe poisoning by organophosphorus (OP) compounds strongly affects the cardiorespiratory system, the effects of sub-lethal exposure to these compounds on the neural control of cardiovascular function are poorly explored. The aim of this study was to evaluate the effects of acute sub-lethal exposure to chlorpyrifos (CPF), a commonly used OP insecticide, on three basic reflex mechanisms involved in blood pressure regulation, the peripheral chemoreflex, the baroreflex and the Bezold-Jarisch reflex...
April 1, 2018: Toxicology
https://www.readbyqxmd.com/read/29470646/reactive-oxygen-radicals-and-gaseous-transmitters-in-carotid-body-activation-by-intermittent-hypoxia
#16
REVIEW
Nanduri R Prabhakar, Ying-Jie Peng, Guoxiang Yuan, Jayasri Nanduri
Sleep apnea is a prevalent respiratory disease characterized by periodic cessation of breathing during sleep causing intermittent hypoxia (IH). Sleep apnea patients and rodents exposed to IH exhibit elevated sympathetic nerve activity and hypertension. A heightened carotid body (CB) chemoreflex has been implicated in causing autonomic abnormalities in IH-treated rodents and in sleep apnea patients. The purpose of this article is to review the emerging evidence showing that interactions between reactive oxygen species (ROS) and gaseous transmitters as a mechanism cause hyperactive CB by IH...
May 2018: Cell and Tissue Research
https://www.readbyqxmd.com/read/29462837/reduced-arterial-vasodilatation-in-response-to-hypoxia-impairs-cerebral-and-peripheral-oxygen-delivery-in-hypertensive-men
#17
Igor A Fernandes, Marcos P Rocha, Monique O Campos, João D Mattos, Daniel E Mansur, Helena N M Rocha, Paulo A C Terra, Vinícius P Garcia, Natália G Rocha, Niels H Secher, Antonio C L Nóbrega
KEY POINTS: Hypoxaemia evokes a repertoire of homeostatic adjustments that maintain oxygen supply to organs and tissues including the brain and skeletal muscles. Because hypertensive patients have impaired endothelial-dependent vasodilatation and an increased sympathetic response to arterial oxygen desaturation, we investigated whether hypertension impairs isocapnic hypoxia-induced cerebral and skeletal muscle hyperaemia to an extent that limits oxygen supply. In middle-aged hypertensive men, vertebral and femoral artery blood flow do not increase in response to isocapnic hypoxia, limiting brain and peripheral hyperaemia and oxygen supply...
April 1, 2018: Journal of Physiology
https://www.readbyqxmd.com/read/29432445/promising-effects-of-xanthine-oxidase-inhibition-by-allopurinol-on-autonomic-heart-regulation-estimated-by-heart-rate-variability-hrv-analysis-in-rats-exposed-to-hypoxia-and-hyperoxia
#18
Stanisław Zajączkowski, Wiesław Ziółkowski, Piotr Badtke, Miłosz A Zajączkowski, Damian J Flis, Adam Figarski, Maria Smolińska-Bylańska, Tomasz H Wierzba
BACKGROUND: It has long been suggested that reactive oxygen species (ROS) play a role in oxygen sensing via peripheral chemoreceptors, which would imply their involvement in chemoreflex activation and autonomic regulation of heart rate. We hypothesize that antioxidant affect neurogenic cardiovascular regulation through activation of chemoreflex which results in increased control of sympathetic mechanism regulating heart rhythm. Activity of xanthine oxidase (XO), which is among the major endogenous sources of ROS in the rat has been shown to increase during hypoxia promote oxidative stress...
2018: PloS One
https://www.readbyqxmd.com/read/29357505/chemoreflex-mediated-arrhythmia-during-apnea-at-5-050-m-in-low-but-not-high-altitude-natives
#19
Stephen A Busch, Hannah Davies, Sean van Diepen, Lydia L Simpson, Frances Sobierajski, Laurel Riske, Mike Stembridge, Philip N Ainslie, Christopher K Willie, Ryan Hoiland, Jonathan P Moore, Craig D Steinback
Peripheral chemoreflex mediated increases in both parasympathetic and sympathetic drive under chronic hypoxia may evoke bradyarrhythmias during apneic periods. We determined whether 1) voluntary apnea unmasks arrhythmia at low (344 m) and high (5,050 m) altitude, 2) high-altitude natives (Nepalese Sherpa) exhibit similar cardiovagal responses at altitude, and 3) bradyarrhythmias at altitude are partially chemoreflex mediated. Participants were grouped as Lowlanders ( n = 14; age = 27 ± 6 yr) and Nepalese Sherpa ( n = 8; age = 32 ± 11 yr)...
April 1, 2018: Journal of Applied Physiology
https://www.readbyqxmd.com/read/29357503/the-hypothalamic-pvn-contributes-to-acute-intermittent-hypoxia-induced-sympathetic-but-not-phrenic-long-term-facilitation
#20
Megan Bardgett Blackburn, Mary Ann Andrade, Glenn M Toney
Acute intermittent hypoxia (AIH) repetitively activates the arterial chemoreflex and triggers a progressive increase of sympathetic nerve activity (SNA) and phrenic nerve activity (PNA) referred to as sympathetic and phrenic long-term facilitation (S-LTF and P-LTF), respectively. Neurons of the hypothalamic paraventricular nucleus (PVN) participate in the arterial chemoreflex, but their contribution to AIH-induced LTF is unknown. To determine this, anesthetized rats were vagotomized and exposed to 10 cycles of AIH, each consisting of ventilation for 3 minutes with 100% O2 followed by 3 minutes with 15% O2 ...
December 21, 2017: Journal of Applied Physiology
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