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Respiratory Physiology & Neurobiology

Ryan W Bavis, Alexandra H Millström, Song M Kim, Carolyn A MacDonald, Caitlin A O'Toole, Kendra Asklof, Amy B McDonough
Chronic exposure to intermittent hyperoxia causes abnormal carotid body development and attenuates the hypoxic ventilatory response (HVR) in neonatal rats. We hypothesized that concurrent exposure to intermittent hypercapnic hypoxia would influence this plasticity. Newborn rats were exposed to alternating bouts of hypercapnic hypoxia (10% O2 /6% CO2 ) and hyperoxia (30-40% O2 ) (5 cycles h-1 , 24 h d-1 ) through 13-14 days of age; the experiment was run twice, once in a background of 21% O2 and once in a background of 30% O2 (i...
November 12, 2018: Respiratory Physiology & Neurobiology
Seham Mustafa
Asthmatic patients often suffer from bronchoconstriction or asthma following breathing hot air or exposure to exercise due to raises the core body temperature. However, the direct effect of heating airways has not been studied yet. The aim of this study is to investigate the effect of heating on tracheal and bronchiolar smooth muscles. Isolated ovine tracheal strips and bronchiolar segments preparations were suspended in organ baths containing Krebs' solution for isometric tension recording. Tissues responses were examined during decreasing and elevating baths temperature (20 °C, 40 °C- 45 °C and 50 °C)...
November 6, 2018: Respiratory Physiology & Neurobiology
Michal G Fortuna, Sebastian Kügler, Swen Hülsmann
Glycine is a primary inhibitory transmitter in the ventral medullary respiratory network, but the functional role of glycinergic neurons for breathing remains a matter of debate. We applied optogenetics to selectively modulate glycinergic neuron activity within regions of the rostral ventral respiratory column (VRC). Responses of the phrenic nerve activity to the light-driven stimulation were studied in the working heart-brainstem preparation from adult glycine transporter 2 Cre mice (GlyT2-Cre), which received a unilateral injection of a Cre-dependent AAV virus into Bötzinger and preBötzinger Complex...
November 2, 2018: Respiratory Physiology & Neurobiology
Andreas Fahlman, Alexandra Epple, Daniel Garcia-Párraga, Todd Robeck, Martin Haulena, Marina Piscitelli-Doshkov, Micah Brodsky
We measured respiratory flow, breath duration, and calculated tidal volume (VT ) in nine belugas (Delphinapterus leucas, mean measured body mass: 628 ± 151 kg, n = 5) housed in managed care facilities. Both spontaneous (resting at station) and trained maximal respirations (chuffs) were measured. The mean (±s.d.) inspiratory VT for spontaneous breaths (16.7 ± 4.7 l, range: 7.518.7 l) was larger than those predicted based on respiratory scaling equations from terrestrial mammals and was 32 ± 10% of estimated total lung capacity (TLCest ) based on an equation from static measurements made on a range of cetaceans and pinniped lungs, and 52 ± 18% of estimated vital capacities (VC , mean: 27...
October 31, 2018: Respiratory Physiology & Neurobiology
Peadar B O'Donohoe, Philip J Turner, Nicky Huskens, Keith J Buckler, Jaideep J Pandit
In humans the intravenous anaesthetic propofol depresses ventilatory responses to hypoxia and CO2 . Animal studies suggest that this may in part be due to inhibition of synaptic transmission between chemoreceptor glomus cells of the carotid body and the afferent carotid sinus nerve. It is however unknown if propofol can also act directly on the glomus cell. Here we report that propofol can indeed inhibit intracellular Ca2+ responses to hypoxia and hypercapnia in isolated rat glomus cells. Neither this propofol effect, nor the glomus cell response to hypoxia in the absence of propofol, were influenced by GABA receptor activation (using GABA, muscimol and baclofen) or inhibition (using bicuculline and 5-aminovaleric acid)...
October 30, 2018: Respiratory Physiology & Neurobiology
Gergely H Fodor, Adam L Balogh, Roberta Sudy, Orsolya Ivankovits-Kiss, Barna Babik, Ferenc Petak
To clarify the potential of dopamine to alter airway tone in the presence of different bronchoconstrictor stimuli, changes in airway function following dopamine administrations were characterized when the bronchial tone was elevated by stimulating the histaminic or cholinergic pathway. Airway resistance, tissue damping and tissue elastance were measured in anesthetized mechanically ventilated rabbits under baseline conditions, during steady-state bronchoconstriction induced by methacholine or histamine, and following intravenous dopamine (5 and 15 μg/kg/min)...
October 24, 2018: Respiratory Physiology & Neurobiology
Qiuli Liu, Margaret T T Wong-Riley
The pituitary adenylate cyclase-activating polypeptide (PACAP) plays an important role in anterior pituitary hormone secretion, neurotransmission, and the control of breathing. Mice lacking PACAP die suddenly mainly in the 2nd postnatal week, coinciding temporally with a critical period of respiratory development uncovered by our laboratory in the rat. The goal of the current study was to test our hypothesis that PACAP expression is reduced during the critical period in normal rats. We undertook immunohistochemistry and optical densitometry of PACAP (specifically PACAP38) in several brain stem respiratory-related nuclei of postnatal days P2-21 rats, and found that PACAP immunoreactivity was significantly reduced at P12 in the pre-Bötzinger complex, nucleus ambiguus, hypoglossal nucleus, and the ventrolateral subnucleus of the nucleus tractus solitarius...
October 22, 2018: Respiratory Physiology & Neurobiology
Caroline A Rickards
Prolonging the therapeutic window for treatment is imperative for survival from a multitude of life-threatening events such as hemorrhage, cardiac arrest, and stroke. Inspiratory resistance breathing is a therapeutic approach that augments the reduction in intrathoracic and intracranial pressure during inspiration, facilitating improvements in vital organ perfusion under conditions of ischemia, such as blood loss and cardiac arrest. In this review a series of studies will be presented assessing the role of inspiratory resistance breathing on responses of cerebral blood flow and cerebral tissue oxygenation under conditions of cardiac arrest and blood loss in animal models, and simulated hemorrhage in humans...
October 16, 2018: Respiratory Physiology & Neurobiology
Tuhin K Roy, Timothy W Secomb
Under resting normoxic conditions, the healthy lung has ample oxygen uptake capacity relative to oxygen demand, but during exercise, increased oxygen demand and utilization become increasingly dependent on ventilation-perfusion matching. A mathematical model is used to investigate the effect of pulmonary flow heterogeneity, as characterized by the coefficient of variation (CV) of capillary blood flow, on pulmonary oxygen uptake in exercise. The model reveals that any level of heterogeneity up to a CV of 3 is consistent with the observed level of arterial oxygen tension under resting conditions, but that such high levels of heterogeneity are incompatible with the levels of oxygen uptake observed during exercise...
October 12, 2018: Respiratory Physiology & Neurobiology
Michael George Zaki Ghali, Gavin Britz, Kun-Ze Lee
The phrenic motor system receives excitatory inspiratory bulbospinal drive from inspiratory pre-motor neurons in the rostral ventral respiratory group and descending inhibition from bulbospinal Bötzinger complex units in the brainstem. While phrenic motoneurons have been extensively studied, a thorough understanding of the role of pre-phrenic interneurons is only beginning to emerge. Pre-phrenic interneurons are located at upper cervical spinal cord levels, as well as within and around the phrenic nucleus at mid-cervical levels...
October 10, 2018: Respiratory Physiology & Neurobiology
Guilherme F Speretta, Eduardo Vieira Lemes, Regina C Vendramini, José V Menani, Daniel B Zoccal, Eduardo Colombari, Débora S A Colombari, Mirian Bassi
Breathing disorders are commonly observed in association with obesity. Here we tested whether high-fat diet (HFD) impairs the chemoreflex ventilatory response. Male Holtzman rats (300-320 g) were fed with standard chow diet (SD) or HFD for 12 weeks. Then, tidal volume (VT ), respiratory frequency (fR ) and pulmonary ventilation (VE ) were determined in conscious rats during basal condition, hypercapnia (7% or 10% CO2 ) or hypoxia (7% O2 ). The mean arterial pressure (MAP), heart rate (HR) and baroreflex sensitivity were also evaluated in conscious rats...
October 9, 2018: Respiratory Physiology & Neurobiology
Mauricio Vallejo, Joseph M Santin, Lynn K Hartzler
Among vertebrate ectotherms, air breathing frequency is generally constrained across warmer temperatures, but decreases during cooling. The brainstem mechanisms that give rise to this ventilatory strategy are unclear. Neuromodulation has recently been shown to stabilize motor circuit output across temperatures. Therefore, we tested the hypothesis that an important neuromodulatory system in respiratory control network, norepinephrine, produces this pattern of respiratory motor activity across temperatures. To this end, we used in vitro brainstem-spinal cord preparations from adult bullfrogs, Lithobates catesbeianus, to assess the role of noradrenergic signaling in shaping the frequency response of the respiratory network during temperature changes...
October 4, 2018: Respiratory Physiology & Neurobiology
Arata Oda, Vilhelmiina Parikka, Liisa Lehtonen, Hanna Soukka
OBJECTIVE: To investigate breathing patterns during respiratory adaptation in preterm infants using the electrical activity of the diaphragm (EAdi) signal. PATIENTS: Infants born between 28 + 0 and 31 + 6 gestational weeks and supported by early nasal continuous positive airway pressure (nCPAP) were studied. The EAdi signal was recorded for 120 min after birth. RESULTS: Eight preterm infants were evaluated. The median EAdi peak value of 19...
September 28, 2018: Respiratory Physiology & Neurobiology
Titto Mathew, S K S Sarada
BACKGROUND: Pulmonary surfactant oxidation leads to alveolar collapse- a condition often noticed in high altitude pulmonary edema (HAPE). The present study was aimed to determine the effect of curcumin prophylaxis in augmenting the phase II antioxidant enzymes and surfactant proteins expression in enabling the pulmonary surfactant homeostasis under hypoxia. METHODS: A549 cells were exposed to 3% hypoxia for different time durations (1 h, 3 h, 6 h, 12 h and 24 h)...
September 27, 2018: Respiratory Physiology & Neurobiology
Sylvia Verbanck, Manuel Paiva
Experimental studies of acinar ventilation heterogeneity (Sacin ) derived from the multiple breath washout have shown the potential of Sacin to pick up structural change in lung disease. Recent Sacin data suggest that even when intra-acinar structure is unaltered, the combination of convection, diffusion and number of acini fed by patent terminal bronchioles can modify Sacin . We show here how Sacin is affected by structural features such as the secondary alveolar septa, intra-acinar ramification and number of ventilated acini...
September 27, 2018: Respiratory Physiology & Neurobiology
S Karrasch, T Radtke, M Simon, A Kronseder, H Dressel, R A Jörres, U Ochmann
We investigated acute effects of inhalation of hypertonic saline solution (HSS) and oxygen (O2 , control exposure) on pulmonary diffusing capacity for nitric oxide (DLNO) and carbon monoxide (DLCO). In a randomized crossover study, 20 healthy, non-smoking subjects were allocated to short-term inhalation of HSS or O2 . Spirometry [(forced expiratory volume in 1 s (FEV1 ) and forced vital capacity (FVC)] and combined single-breath DLNO-DLCO measurements were performed before and immediately after inhalation of either HSS or O2 ...
September 24, 2018: Respiratory Physiology & Neurobiology
A Mark Evans
Regulation of breathing is critical to our capacity to accommodate deficits in oxygen availability and demand during, for example, sleep and ascent to altitude. Key to this are two reflex responses, hypoxic pulmonary vasoconstriction (HPV), which aids ventilation-perfusion matching at the lungs, and the hypoxic ventilatory response (HVR) which accelerates ventilation. In 2004 I proposed that HPV might be mediated by the AMP-activated protein kinase, which governs cell autonomous metabolic homeostasis. Pharmacological evidence was presented in support of this view, and the hypothesis extended to incorporate a role for AMPK in regulating carotid body afferent input responses during hypoxia and thus the HVR...
September 19, 2018: Respiratory Physiology & Neurobiology
Giuseppe Piccione, Elisabetta Giudice, Claudia Giannetto, Jacopo P Mortola
Heart rate (FH) accelerates in inspiration and decelerates in expiration, a phenomenon known as Respiratory Sinus Arrhythmia (RSA). Although the presence of RSA has been documented in many species, how its magnitude compares among species is unknown. We asked whether the magnitude of RSA in a large mammal, the horse, differed from that of previously measured humans. From electrocardiogram and pneumography, the peaks and troughs of FH were identified breath-by-breath in four horses (Italian Saddlebred geldings) during resting wakefulness...
September 18, 2018: Respiratory Physiology & Neurobiology
Sevda C Aslan, William B McKay, Goutam Singh, Alexander V Ovechkin
Maximum inspiratory and expiratory pressure values (PImax and PEmax ) are indirect measures of respiratory muscle strength that, in healthy adults, are known to be significantly lower in women compared to men. In part, sex differences in breathing kinematics, lung size, body composition, muscle mass, and muscle fiber composition are thought to be responsible for these effects. However, it is not known whether respiratory muscle activation during maximum respiratory efforts is also sex-specific. In this study, we addressed whether respiratory multi-muscle activation patterns during PImax and PEmax efforts are different between healthy women and men...
September 15, 2018: Respiratory Physiology & Neurobiology
Ömer Faruk Yilmaz, Mustafa Özdal
The combined effects of swimming on the inspiratory muscles and pulmonary functions are not well known. The aim of the present study was to determine the acute, chronic, and combined effects of swimming on the pulmonary functions and respiratory muscles of competitive swimmers. Thirty males (15 in the experimental group [EG] and 15 in the control group [CG]) participated in this study. The EG subjects participated in an 8-week swim training program and performed 1 day before and after an 8-week 100-m swimming event...
September 11, 2018: Respiratory Physiology & Neurobiology
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