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acute intermittent hypoxia

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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
#1
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/29623044/long-term-intermittent-work-at-high-altitude-right-heart-functional-and-morphological-status-and-associated-cardiometabolic-factors
#2
Julio Brito, Patricia Siques, Rosario López, Raul Romero, Fabiola León-Velarde, Karen Flores, Nicole Lüneburg, Juliane Hannemann, Rainer H Böger
Background: Living at high altitude or with chronic hypoxia implies functional and morphological changes in the right ventricle and pulmonary vasculature with a 10% prevalence of high-altitude pulmonary hypertension (HAPH). The implications of working intermittently (day shifts) at high altitude (hypobaric hypoxia) over the long term are still not well-defined. The aim of this study was to evaluate the right cardiac circuit status along with potentially contributory metabolic variables and distinctive responses after long exposure to the latter condition...
2018: Frontiers in Physiology
https://www.readbyqxmd.com/read/29584516/effect-of-intermittent-hypoxia-training-for-dizziness-a-randomized-controlled-trial
#3
Xiao Bao, Jie-Wen Tan, Ying Long, Howe Liu, Hui-Yu Liu
OBJECTIVE: To study the effect of intermittent hypoxia training (IHT) for dizziness. DESIGN: A single-blind, randomized controlled trial. All participants were recruited from a rehabilitation department in an acute university-affiliated hospital. INTERVENTION: Participants with dizziness were randomly assigned to two groups (IHT group and control group). The Dizziness Handicap Inventory (DHI), Activities-specific Balance Confidence Scale (ABC), Vertigo Visual Analog Scale (VVAS) were conducted at baseline, end of the 4th week...
March 27, 2018: Journal of Sport Rehabilitation
https://www.readbyqxmd.com/read/29565772/il-1-receptor-activation-undermines-respiratory-motor-plasticity-after-systemic-inflammation
#4
Austin D Hocker, Adrianne Genest Huxtable
Inflammation undermines respiratory motor plasticity, yet we are just beginning to understand the inflammatory signaling involved. Since interleukin-1 (IL-1) signaling promotes or inhibits plasticity in other CNS regions, we tested the following hypotheses: 1) IL-1 receptor (IL-1R) activation after systemic inflammation is necessary to undermine phrenic long-term facilitation (pLTF), a model of respiratory motor plasticity induced by acute intermittent hypoxia (AIH), and 2) spinal IL-1β is sufficient to undermine pLTF...
March 22, 2018: Journal of Applied Physiology
https://www.readbyqxmd.com/read/29541032/the-influence-of-co-2-and-exercise-on-hypobaric-hypoxia-induced-pulmonary-edema-in-rats
#5
Ryan L Sheppard, Joshua M Swift, Aaron Hall, Richard T Mahon
Introduction: Individuals with a known susceptibility to high altitude pulmonary edema (HAPE) demonstrate a reduced ventilation response and increased pulmonary vasoconstriction when exposed to hypoxia. It is unknown whether reduced sensitivity to hypercapnia is correlated with increased incidence and/or severity of HAPE, and while acute exercise at altitude is known to exacerbate symptoms the effect of exercise training on HAPE susceptibility is unclear. Purpose: To determine if chronic intermittent hypercapnia and exercise increases the incidence of HAPE in rats...
2018: Frontiers in Physiology
https://www.readbyqxmd.com/read/29528458/effects-of-low-oxygen-during-chorioallantoic-membrane-development-on-post-hatch-growing-performance-of-broiler-chickens
#6
S Druyan, M Ruzal, D Shinder, A Haron
The prenatal circulatory system is adaptive and capable of plasticity designed for the needs of the growing tissue. When a broiler embryo is faced with hypoxic stress, the process of angiogenesis in tissues begins. Exposure to hypoxic conditions of 17% oxygen during the chorioallantoic membrane (CAM) development (E5 to E12) affected the circulatory system and contributed to an increase in the blood oxygen carrying capacity. The present study aimed to evaluate the effects of hypoxic exposure during CAM development on post-hatch performance of broilers and to examine whether hypoxic exposure improved sustainability of birds exposed to acute heat stress...
March 8, 2018: Poultry Science
https://www.readbyqxmd.com/read/29513151/systemic-inflammation-inhibits-serotonin-receptor-2-induced-phrenic-motor-facilitation-upstream-from-bdnf-trkb-signaling
#7
Ibis M Agosto, Nicole L Nichols, Gordon S Mitchell
Although systemic inflammation induced by even a low dose of lipopolysaccharide (LPS, 100uL/kg) impairs respiratory motor plasticity, little is known concerning cellular mechanisms giving rise to this inhibition. Phrenic motor facilitation (pMF) is a form of respiratory motor plasticity elicited by pharmacological agents applied to the cervical spinal cord, or by acute intermittent hypoxia (AIH; 3, 5 min hypoxic episodes); when elicited by AIH, pMF is known as phrenic long-term facilitation (pLTF). AIH consisting of moderate hypoxic episodes (mAIH, PaO2 = 35-55 mmHg) elicits pLTF via the Q- pathway to pMF, a mechanism that requires spinal serotonin (5HT2) receptor activation and new BDNF protein synthesis...
March 7, 2018: Journal of Neurophysiology
https://www.readbyqxmd.com/read/29466787/a-strategy-for-optimizing-the-combination-of-active-components-based-on-chinese-medicinal-formula-sheng-mai-san-for-myocardial-ischemia
#8
Fang Li, Xiao-Xue Fan, Chun Chu, Yu Zhang, Jun-Ping Kou, Bo-Yang Yu
BACKGROUND/AIMS: Traditional Chinese medicine (TCM) has been used in clinical practice for thousands of years and has accumulated considerable knowledge concerning the in vivo efficacy of targeting complicated diseases. TCM formulae are a mixture of hundreds of chemical components with multiple potential targets, essentially acting as a combination therapy of multi-component drugs. However, the obscure substances and the unclear molecular mechanisms are obstacles to their further development and internationalization...
February 16, 2018: Cellular Physiology and Biochemistry
https://www.readbyqxmd.com/read/29423544/high-intensity-interval-training-in-hypoxia-does-not-affect-muscle-hif-responses-to-acute-hypoxia-in-humans
#9
Stefan De Smet, Gommaar D'Hulst, Chiel Poffé, Ruud Van Thienen, Emanuele Berardi, Peter Hespel
PURPOSE: The myocellular response to hypoxia is primarily regulated by hypoxia-inducible factors (HIFs). HIFs thus conceivably are implicated in muscular adaptation to altitude training. Therefore, we investigated the effect of hypoxic versus normoxic training during a period of prolonged hypoxia ('living high') on muscle HIF activation during acute ischaemia. METHODS: Ten young male volunteers lived in normobaric hypoxia for 5 weeks (5 days per week, ~ 15.5 h per day, FiO2: 16...
February 8, 2018: European Journal of Applied Physiology
https://www.readbyqxmd.com/read/29373484/mechanisms-of-cardiovascular-protection-associated-with-intermittent-hypobaric-hypoxia-exposure-in-a-rat-model-role-of-oxidative-stress
#10
Miguel Aguilar, Alejandro González-Candia, Jorge Rodríguez, Catalina Carrasco-Pozo, Daniel Cañas, Claudio García-Herrera, Emilio A Herrera, Rodrigo L Castillo
More than 140 million people live and works (in a chronic or intermittent form) above 2500 m worldwide and 35 million live in the Andean Mountains. Furthermore, in Chile, it is estimated that 55,000 persons work in high altitude shifts, where stays at lowlands and interspersed with working stays at highlands. Acute exposure to high altitude has been shown to induce oxidative stress in healthy human lowlanders, due to an increase in free radical formation and a decrease in antioxidant capacity. However, in animal models, intermittent hypoxia (IH) induce preconditioning, like responses and cardioprotection...
January 26, 2018: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/29357503/the-hypothalamic-pvn-contributes-to-acute-intermittent-hypoxia-induced-sympathetic-but-not-phrenic-long-term-facilitation
#11
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
https://www.readbyqxmd.com/read/29233741/cyclooxygenase-enzyme-activity-does-not-impair-respiratory-motor-plasticity-after-one-night-of-intermittent-hypoxia
#12
Adrianne G Huxtable, Elizabeth Kopp, Brendan J Doughtery, Jyoti J Watters, Gordon S Mitchell
Although inflammation is prevalent in many clinical disorders challenging breathing, we are only beginning to understand the impact of inflammation on neural mechanisms of respiratory control. We recently demonstrated one form of respiratory motor plasticity is extremely sensitive to even mild inflammation induced by a single night (8 h) of intermittent hypoxia (IH-1), mimicking aspects of obstructive sleep apnea. Specifically, phrenic long-term facilitation (pLTF) following moderate acute intermittent hypoxia (AIH) is abolished by IH-1, but restored by high doses of the non-steroidal anti-inflammatory drug, ketoprofen...
December 9, 2017: Respiratory Physiology & Neurobiology
https://www.readbyqxmd.com/read/29220311/quantifying-the-effects-of-acute-hypoxic-exposure-on-exercise-performance-and-capacity-a-systematic-review-and-meta-regression
#13
Sanjoy K Deb, Daniel R Brown, Lewis A Gough, Christopher P Mclellan, Paul A Swinton, S Andy Sparks, Lars R Mcnaughton
OBJECTIVE: To quantify the effects of acute hypoxic exposure on exercise capacity and performance, which includes continuous and intermittent forms of exercise. DESIGN: A systematic review was conducted with a three-level mixed effects meta-regression. The ratio of means method was used to evaluate main effects and moderators providing practical interpretations with percentage change. DATA SOURCES: A systemic search was performed using three databases (Google scholar, PubMed and SPORTDiscus)...
March 2018: European Journal of Sport Science
https://www.readbyqxmd.com/read/29212793/pacap-6-38-or-kynurenate-microinjections-into-the-rvlm-prevent-development-of-sympathetic-long-term-facilitation-following-acute-intermittent-hypoxia
#14
Zohra M Kakall, Paul M Pilowsky, Melissa Mj Farnham
BACKGROUND AND PURPOSE: Intermittent hypoxia causes a persistent increase in sympathetic activity, which progresses to hypertension in chronic conditions such as obstructive sleep apnea (OSA). Pituitary adenylate cyclase activating polypeptide (PACAP) is an excitatory neurotransmitter that causes long-lasting sympathetic excitation. We aimed to determine if intermittent activation of the rostral ventrolateral medulla (RVLM) causes PACAP-mediated elevation of sympathetic nerve activity (sSNA), termed sympathetic long-term facilitation (sLTF)...
December 6, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/29159869/acute-intermittent-hypoxia-with-concurrent-hypercapnia-evokes-p2x-and-trpv1-receptor-dependent-sensory-long-term-facilitation-in-na%C3%A3-ve-carotid-bodies
#15
Arijit Roy, Melissa M J Farnham, Fatemeh Derakhshan, Paul M Pilowsky, Richard J A Wilson
KEY POINTS: Activity-dependent plasticity can be induced in carotid body (CB) chemosensory afferents without chronic intermittent hypoxia (CIH) preconditioning by acute intermittent hypoxia coincident with bouts of hypercapnia (AIH-Hc). Several properties of this acute plasticity are shared with CIH-dependent sensory long-term facilitation (LTF) in that induction is dependent on 5-HT, angiotensin II, protein kinase C and reactive oxygen species. Several properties differ from CIH-dependent sensory LTF; H2 O2 appears to play no part in induction, whereas maintenance requires purinergic P2X2/3 receptor activation and is dependent on transient receptor potential vanilloid type 1 (TRPV1) receptor sensitization...
November 21, 2017: Journal of Physiology
https://www.readbyqxmd.com/read/29130497/ubc-nepal-expedition-acclimatization-to-high-altitude-increases-spinal-motoneurone-excitability-during-fatigue-in-humans
#16
Luca Ruggiero, Alexandra F Yacyshyn, Jane Nettleton, Chris J McNeil
KEY POINTS: Acute exposure and acclimatization to hypoxia are associated with an impairment and partial recovery, respectively, of the capability of the central nervous system to drive muscles during prolonged efforts. Motoneurones play a vital role in muscle contraction and in fatigue, although the effect of hypoxia on motoneurone excitability during exercise has not been assessed in humans. We studied the impact of fatigue on motoneurone excitability in normoxia, acute and chronic exposure (5050 m) to hypoxia...
November 11, 2017: Journal of Physiology
https://www.readbyqxmd.com/read/29107023/intermittent-hypoxia-alters-dose-dependent-caffeine-effects-on-renal-prostanoids-and-receptors-in-neonatal-rats
#17
Kay D Beharry, Charles L Cai, Kultida Soontarapornchai, Taimur Ahmad, Gloria B Valencia, Jacob V Aranda
Caffeine, one of the most commonly prescribed drugs in preterm neonates, is given in standard or suprapharmacologic doses. Although known as a diuretic, its effects in the neonatal kidneys are not well studied. We tested the hypothesis that neonatal intermittent hypoxia (IH) and high caffeine doses (HCD) alter renal regulators of vasomotor tone and water balance. Newborn rats were randomized to room air, hyperoxia, or IH and treated with standard or high caffeine doses; or placebo saline. Renal prostanoids; histopathology; and cyclooxygenase (COX), prostanoid receptor, and aquaporin (AQP) immunoreactivity were determined...
October 26, 2017: Prostaglandins & Other Lipid Mediators
https://www.readbyqxmd.com/read/29081358/spinal-activation-of-protein-kinase-c-elicits-phrenic-motor-facilitation
#18
Michael J Devinney, Gordon S Mitchell
The protein kinase C family regulates many cellular functions, including multiple forms of neuroplasticity. The novel PKCθ and atypical PKCζ isoforms have been implicated in distinct forms of spinal, respiratory motor plasticity, including phrenic motor facilitation (pMF) following acute intermittent hypoxia or inactivity, respectively. Although these PKC isoforms are critical in regulating spinal motor plasticity, other isoforms may be important for phrenic motor plasticity. We tested the impact of conventional/novel PKC activator, phorbol 12-myristate 13-acetate (PMA) on pMF...
November 2, 2017: Respiratory Physiology & Neurobiology
https://www.readbyqxmd.com/read/29074711/enhanced-cerebral-perfusion-during-brief-exposures-to-cyclic-intermittent-hypoxemia
#19
Xiaoli Liu, Diqun Xu, James R Hall, Sarah Ross, Shande Chen, Howe Liu, Robert T Mallet, Xiangrong Shi
Cerebral vasodilation and increased cerebral oxygen extraction help maintain cerebral oxygen uptake in the face of hypoxemia. This study examined cerebrovascular responses to intermittent hypoxemia in eight healthy men breathing 10% O2 for 5 cycles, each 6 min, interspersed with 4 min of room air breathing. Hypoxia exposures raised heart rate ( P < 0.01) without altering arterial pressure, and increased ventilation ( P < 0.01) by expanding tidal volume. Arterial oxygen saturation ([Formula: see text]) and cerebral tissue oxygenation ([Formula: see text]) fell ( P < 0...
December 1, 2017: Journal of Applied Physiology
https://www.readbyqxmd.com/read/29074449/intermittent-but-not-sustained-moderate-hypoxia-elicits-long-term-facilitation-of-hypoglossal-motor-output
#20
Julia E R Wilkerson, Michael Devinney, Gordon S Mitchell
Phrenic long-term facilitation (pLTF) is a form of serotonin-dependent respiratory motor plasticity induced by moderate acute intermittent hypoxia (AIH), but not by moderate acute sustained hypoxia (ASH) of similar cumulative duration. Thus, moderate AIH-induced pLTF is sensitive to the pattern of hypoxia. On the other hand, pLTF induced by severe AIH protocols is neither pattern sensitive nor serotonin dependent (it converts to an adenosine-dependent mechanism). Although moderate AIH also induces hypoglossal LTF (hLTF), no data are available concerning its sensitivity/insensitivity to the pattern of hypoxia...
October 23, 2017: Respiratory Physiology & Neurobiology
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