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Respiratory Physiology & Neurobiology

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...
October 12, 2016: Respiratory Physiology & Neurobiology
Rogério Santos Cde Oliveira Cruz, Tiago Turnes, Rafael Alves de Aguiar, Fabrizio Caputo
The off-transient pulmonary oxygen uptake (V̇O2) response to a single bout of intense, exhaustive exercise has been characterized over the years by a second-order exponential model. In this paper, we report the superiority of a third-order exponential decay in describing the V̇O2 off-kinetics after a maximal cycling exercise lasting 60-s. Our findings are in accordance with a biphasic pattern of phosphocreatine resynthesis when muscle pH is affected.
October 12, 2016: Respiratory Physiology & Neurobiology
Nazzareno Fagoni, Anna Taboni, Giovanni Vinetti, Sara Bottarelli, Christian Moia, Aurélién Bringard, Guido Ferretti
INTRODUCTION: We tested the hypothesis that the alveolar gas composition at the transition between the steady phase II (φ2) and the dynamic phase III (φ3) of the cardiovascular response to apnoea may lay on the physiological breaking point curve (Lin et al., 1974). METHODS: Twelve elite divers performed maximal and φ2-interrupted apnoeas, in air and pure oxygen. We recorded beat-by-beat arterial blood pressure and heart rate; we measured alveolar oxygen and carbon dioxide pressures (PAO2 and PACO2, respectively) before and after apnoeas; we calculated the PACO2 difference between the end and the beginning of apnoeas (ΔPACO2)...
October 6, 2016: Respiratory Physiology & Neurobiology
Aline Amérand, Hélène Mortelette, Marc Belhomme, Christine Moisan
Silvering, the last metamorphosis in the eel life cycle induces morphological and physiological modifications in yellow eels (sedentary stage). It pre-adapts them to cope with the extreme conditions they will encounter during their 6000-km spawning migration. A previous study showed that silver eels are able to cope with reactive oxygen species (ROS) over-production linked to an increase in aerobic metabolism during sustained swimming, but the question remains as to whether this mechanism is associated with silvering...
October 4, 2016: Respiratory Physiology & Neurobiology
Nirupama S Wijesuriya, Chaminda Lewis, Jane E Butler, Bonsan B Lee, Amy S Jordan, David J Berlowitz, Danny J Eckert
Obstructive sleep apnoea (OSA) is highly prevalent in people with tetraplegia. Nasal congestion, a risk factor for OSA, is common in people with tetraplegia. The purpose of this study was to quantify objective and perceived nasal resistance and its stability over four separate days in people with tetraplegia and OSA (n=8) compared to able-bodied controls (n=6). Awake nasal resistance was quantified using gold standard choanal pressure recordings (days 1 and 4) and anterior rhinomanometry (all visits). Nasal resistance (choanal pressure) was higher in people with tetraplegia versus controls (5...
October 3, 2016: Respiratory Physiology & Neurobiology
Joshua P Nederveen, Daniel A Keir, Lorenzo K Love, Harry B Rossiter, John M Kowalchuk
We examined the effect of heavy-intensity 'priming' exercise on the rate of adjustment of pulmonary O2 uptake (τV˙O2p) initiated from elevated intensities. Fourteen men (separated into two groups: τV˙O2p≤25s [Fast] or τV˙O2p>25s [Slow]) completed step-transitions from 20W to 45% lactate threshold (LT; lower-step, LS) and 45% to 90%LT (upper-step, US) performed (i) without; and (ii) with US preceded by heavy-intensity exercise (HUS). Breath-by-breath V˙O2p and near-infrared spectroscopy-derived muscle deoxygenation ([HHb+Mb]) were measured...
September 28, 2016: Respiratory Physiology & Neurobiology
Stéphane Doutreleau, Irina Enache, Cristina Pistea, Fabrice Favret, Evelyne Lonsdorfer, Stéphane Dufour, Anne Charloux
We measured the effects of adding CO2 to an inhaled hypoxic gas mixture on cardio-respiratory parameters during maximal exercise. Eight young males performed four incremental maximal exercise tests on cycle under ambient air, hypoxia (FIO2 0.125), inhaled CO2 (FICO2 0.045), and combination of hypoxia and inhaled CO2. The highest ventilation (VE) and VE/CO2 output were recorded in CO2 inhalation and combined treatments. Arterial O2 partial pressure was higher in combined than in hypoxia treatment, but the difference between the treatments narrowed from rest to end-exercise, at least partly because the magnitude of the increase in VE (%) at exercise was smaller in combined treatment than in hypoxia...
September 26, 2016: Respiratory Physiology & Neurobiology
S Vakali, I Vogiatzis, A Florou, S Giavi, S Zakynthinos, N G Papadopoulos, Ch Gratziou
Diagnosis of exercise-induced bronchoconstriction (EIB) requires the use of bronchial provocation tests (BPTs). We assessed exercise-induced respiratory symptoms (EIRS), EIB and asthma in athletes and evaluated the validity of BPTs in the diagnosis of EIB. Rhinitis and atopy were also assessed. Athletes with (n=55) and without previous asthma diagnosis (n=145) were tested by skin prick tests, lung function and eNO measurements. EIRS were recorded and EIB was assessed by methacholine (Mch), eucapnic voluntary hyperpnoea (EVH), mannitol and exercise test...
September 24, 2016: Respiratory Physiology & Neurobiology
Brody H Foy, David Kay, Rafel Bordas
Many lung diseases lead to an increase in ventilation heterogeneity (VH). Two clinical practices for the measurement of patient VH are in vivo imaging, and the inert gas multiple breath washout (MBW). In this study computational modelling was used to compare the responses of MBW indices LCI and scond and MRI measured global and local ventilation indices, σr and σlocal, to constriction of airways in the conducting zone of the lungs. The simulations show that scond, LCI and σr behave quite similarly to each other, all being sensitive to increases in the severity of constriction, while exhibiting little sensitivity to the depth at which constriction occurs...
September 24, 2016: Respiratory Physiology & Neurobiology
Andrée Dionne, Mario Leone, David E Andrich, Louis Pérusse, Alain Steve Comtois
We aimed to determine the effect of aquatic cycling and different levels of immersion on respiratory responses in healthy and heart disease (HD) volunteers. Thirty-four age matched volunteers, 21 HD and 13 healthy controls (HC) took part in this study. The ventilatory pattern, phase 1VE and steady-state ventilatory responses to progressive exercise from 40 to peak rpm, were measured while participants exercised on a water stationary bike (WSB) at different levels of immersion. No effect of immersion was observed on steady-state respiratory responses in the HD group, but immersion reduced VE phase 1 by ∼79% at pedaling cadences of 40, 50 and 60rpm...
September 23, 2016: Respiratory Physiology & Neurobiology
Alessandra Adami, Robert Cao, Janos Porszasz, Richard Casaburi, Harry B Rossiter
Low muscle oxidative capacity contributes to exercise intolerance in chronic obstructive pulmonary disease (COPD). Near-infrared spectroscopy (NIRS) allows non-invasive determination of the muscle oxygen consumption (mV̇O2) recovery rate constant (k), which is proportional to oxidative capacity assuming two conditions are met: 1) exercise intensity is sufficient to fully-activate mitochondrial oxidative enzymes; 2) sufficient O2 availability. We aimed to determine reproducibility (coefficient of variation, CV; intraclass correlation coefficient, ICC) of NIRS k assessment in the gastrocnemius of 64 participants with (FEV1 64±23%predicted) or without COPD (FEV1 98±14%predicted)...
September 19, 2016: Respiratory Physiology & Neurobiology
A M Edwards, D Graham, S Bloxham, G P Maguire
OBJECTIVE: To examine the efficacy of inspiratory muscle training (IMT) as a non-intrusive and practical intervention to stimulate improved functional fitness in adults with obesity. As excess adiposity of the chest impedes the mechanics of breathing, targeted re-training of the inspiratory muscles may ameliorate sensations of breathlessness, improve physical performance and lead to greater engagement in physical activity. METHODS: Sixty seven adults (BMI=36 ±6...
September 13, 2016: Respiratory Physiology & Neurobiology
A J Bates, R Cetto, D J Doorly, R C Schroter, N S Tolley, A Comerford
This paper considers factors that play a significant role in determining inspiratory pressure and energy losses in the human trachea. Previous characterisations of pathological geometry changes have focussed on relating airway constriction and subsequent pressure loss, however many pathologies that affect the trachea cause deviation, increased curvature, constriction or a combination of these. This study investigates the effects of these measures on tracheal flow mechanics, using compressive goitre (a thyroid gland enlargement) as an example...
September 9, 2016: Respiratory Physiology & Neurobiology
D H McFarland, B Martin-Harris, A-J Fortin, K Humphries, E Hill, K Armeson
This study was designed to investigate the significance of bolus types and volumes, delivery methods and swallowing instructions on lung volume at swallowing initiation in normal subjects in a single experiment using a multifactorial approach. Our broad range goal was to determine optimal lung volume range associated with swallowing initiation to provide training targets for dysphagic patients with disordered respiratory-swallow coordination. Our hypothesis was that swallows would be initiated within a limited range of quiet breathing lung volumes regardless of bolus volume, consistency or task...
September 6, 2016: Respiratory Physiology & Neurobiology
Matteo Pecchiari, Dejan Radovanovic, Pierachille Santus, Edgardo D'Angelo
PURPOSE: To determine whether the analysis of the slow expiratory transpulmonary pressure-volume (PL-V) curve provides an alternative to the single-breath nitrogen test (SBN) for the assessment of the closing volume (CV). METHODS: SBN test and slow deflation PL-V curve were simultaneously recorded in 40 healthy subjects and 43 COPD patients. Onset of phase IV identified CV in SBN test (CVSBN), whereas in the PL-V curve CV was identified by: a) deviation from the exponential fit (CVexp), and b) inflection point of the interpolating sigmoid function (CVsig)...
September 6, 2016: Respiratory Physiology & Neurobiology
Jason M Bourke, Lawrence M Witmer
We tested the aerodynamic function of nasal conchae in birds using CT data from an adult male wild turkey (Meleagris gallopavo) to construct 3D models of its nasal passage. A series of digital "turbinectomies" were performed on these models and computational fluid dynamic analyses were performed to simulate resting inspiration. Models with turbinates removed were compared to the original, unmodified control airway. Results revealed that the four conchae found in turkeys, along with the crista nasalis, alter the flow of inspired air in ways that can be considered baffle-like...
September 6, 2016: Respiratory Physiology & Neurobiology
Egidio Beretta, Francesca Lanfranconi, Simone Grasso Gabriele, Manuela Bartesaghi, Alemayehu Hailu Kinfu, Giuseppe Miserocchi
DLCO measured in hypoxia must be corrected due to the higher affinity (increase in coefficient θ) of CO with Hb. We propose an adjustment accounting for individual changes in the equation relating DLCO to subcomponents Dm (membrane diffusive capacity) and Vc (lung capillary volume): 1/DLCO=1/Dm+1/θVc. We adjusted the individual DLCO measured in hypoxia (HA, 3269m) by interpolating the 1/DLCO to the sea level (SL) 1/θ value. Nineteen healthy subjects were studied at SL and HA. Based on the proposed adjustment, DLCO increased in HA in 53% of subjects, reflecting the increase in Dm that largely overruled the decrease in Vc...
September 2, 2016: Respiratory Physiology & Neurobiology
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)...
September 2, 2016: Respiratory Physiology & Neurobiology
Dale R Bergren, Jimmie L Valentine
Therapeutic natural products and medicinal herbs has gained popularity. The anti-antigenic action of the plant alkaloid nordihydroguaiaretic acid (NDGA) was studied in ovalbumin (OA)-sensitized guinea pigs. In one series of experiments conscious, non-sedated guinea pigs were challenged with OA aerosol. Specific airway resistance (SRAW) was monitored using a two-chambered whole-body plethysmograph. OA aerosol increased SRAW above that produced by vehicle administration. Prior NDGA administration by a 1min 0...
September 2, 2016: Respiratory Physiology & Neurobiology
Steffen Wirth, Lisa Artner, Tobias Broß, Sara Lozano-Zahonero, Johannes Spaeth, Stefan Schumann
In paediatric patients positive end-expiratory pressure (PEEP) is traditionally set lower than in adults. We investigated whether moderately higher PEEP improves respiratory mechanics and regional ventilation. Therefore, 40 children were mechanically ventilated with PEEP 2 and 5 cmH2O. Volume-dependent compliance profiles were analysed as a measure of intratidal recruitment/derecruitment. Regional ventilation was assessed using electrical impedance tomography. Mean compliance was 17.9±9.9 mL·cmH2O(-1) (PEEP 2 cmH2O), and 19...
August 29, 2016: Respiratory Physiology & Neurobiology
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