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Journal of Physiology

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https://www.readbyqxmd.com/read/27902842/vagal-denervation-inhibits-the-increase-in-pulmonary-blood-flow-during-partial-lung-aeration-at-birth
#1
Justin A R Lang, James T Pearson, Corinna Binder-Heschl, Megan J Wallace, Melissa L Siew, Marcus J Kitchen, Arjan B Te Pas, Robert A Lewis, Graeme R Polglase, Mikiyasu Shirai, Stuart B Hooper
Air entry into the lungs at birth triggers major cardiovascular changes, including a large increase in pulmonary blood flow (PBF) that is not spatially related to regional lung aeration. To investigate the possible underlying role of a vagally-mediated stimulus, we used simultaneous phase-contrast X-ray imaging and angiography in near-term (30 days of gestation) vagotomised (n = 15) or sham-operated (n = 15) rabbit kittens. Rabbits were imaged before ventilation, when one lung was ventilated (unilateral) with 100% nitrogen (N2 ), air or 100% oxygen (O2 ), before all kittens were switched to unilateral ventilation in air, then ventilation of both lungs using air...
November 30, 2016: Journal of Physiology
https://www.readbyqxmd.com/read/27902841/dynamical-effects-of-calcium-sensitive-potassium-currents-on-voltage-and-calcium-alternans
#2
Matthew Kennedy, Donald M Bers, Nipavan Chiamvimonvat, Daisuke Sato
Cardiac alternans is a precursor to life-threatening arrhythmias. Alternans can be caused by instability of the membrane voltage (Vm ), instability of the intracellular Ca (Cai ) cycling, or both. Vm dynamics and Cai dynamics are coupled via Ca-sensitive currents. In cardiac myocytes, there are several Ca-sensitive potassium (K) currents such as the slowly activating delayed rectifier current (IKs ) and the small conductance Ca-activated potassium (SK) current (ISK ). However, the role of these currents in the development of arrhythmias is not well understood...
November 30, 2016: Journal of Physiology
https://www.readbyqxmd.com/read/27901270/adipose-tissue-inflammation-by-intermittent-hypoxia-mechanistic-link-between-obstructive-sleep-apnoea-and-metabolic-dysfunction
#3
Silke Ryan
Obstructive sleep apnoea (OSA) is a highly prevalent condition and recognized as a major public health burden conveying a significant risk of cardiometabolic diseases and mortality. Type 2 diabetes (T2D), insulin resistance (IR) and glucose tolerance are common in subjects with OSA and this association is at least in part independent of the effects of obesity. Continuous positive airway pressure (CPAP) is the treatment of choice for the majority of patients with OSA but the benefit of CPAP on glycaemic health is uncertain...
November 29, 2016: Journal of Physiology
https://www.readbyqxmd.com/read/27900769/influence-of-menstrual-phase-and-arid-vs-humid-heat-stress-on-autonomic-and-behavioural-thermoregulation-during-exercise-in-trained-but-unacclimated-women
#4
Tze-Huan Lei, Stephen R Stannard, Blake G Perry, Zachary J Schlader, James D Cotter, Toby Mündel
We studied thermoregulatory responses of ten well-trained (VO2 max, 57 (7) mL min(-1) kg(-1) ) eumenorrheic women exercising in dry and humid heat, across their menstrual cycle. They completed four trials, each of resting and cycling at fixed intensities (125 and 150 W), to assess autonomic regulation, then self-paced intensity (30-min work trial), to assess behavioural regulation. Trials were in early-follicular (EF) and mid-luteal (ML) phases in dry (DRY) and humid (HUM) heat matched for wet bulb globe temperature (WBGT, 27°C)...
November 29, 2016: Journal of Physiology
https://www.readbyqxmd.com/read/27896815/how-and-why-are-calcium-currents-curtailed-in-the-skeletal-muscle-voltage-gated-calcium-channels
#5
Bernhard E Flucher, Petronel Tuluc
Voltage-gated calcium channels represent the sole mechanism converting electrical signals of excitable cells into cellular functions such as contraction, secretion, and gene regulation. Specific voltage-sensing domains detect changes in membrane potentials and control channel gating. Calcium ions entering through the channel function as second messengers regulating cell functions; with the exception of skeletal muscle, where CaV 1.1 is essentially not functioning as channel but activates calcium release from intracellular stores...
November 29, 2016: Journal of Physiology
https://www.readbyqxmd.com/read/27891626/does-trans-spinal-and-local-dc-polarization-affect-presynaptic-inhibition-and-post-activation-depression
#6
D Kaczmarek, J Ristikankare, E Jankowska
Direct current (DC) polarization has been demonstrated to alleviate the effects of various deficits in the operation of the central nervous system. However, the effects of trans-spinal DC stimulation (tsDCS) have been investigated less extensively than the effects of transcranial DC stimulation (tDCS), and their cellular mechanisms have not been elucidated. The main objectives of this study were, therefore, to extend our previous analysis of DC effects on the excitability of primary afferents and synaptic transmission by examining the effects of DC on two spinal modulatory feed-back systems, presynaptic inhibition and post-activation depression, in an anaesthetized rat preparation...
November 28, 2016: Journal of Physiology
https://www.readbyqxmd.com/read/27891612/neurovascular-mechanisms-underlying-augmented-cold-induced-reflex-cutaneous-vasoconstriction-in-human-hypertension
#7
Jody L Greaney, W Larry Kenney, Lacy M Alexander
Despite ample evidence of dysregulated sympathetic control of the peripheral vasculature in hypertension, no studies have examined integrated neurovascular function during cold stress in hypertensive adults (HTN). We hypothesized that (1) whole-body cooling would elicit greater cutaneous vasoconstriction and greater increases in skin sympathetic nervous system activity (SSNA) in HTN (n = 14; 56 ± 2 yrs) compared to age-matched normotensive adults (NTN; n = 14; 55 ± 2 yrs) and (2) augmented reflex vasoconstriction in HTN would be mediated by an increase in cutaneous vascular adrenergic sensitivity and a greater contribution of non-adrenergic sympathetic co-transmitters...
November 28, 2016: Journal of Physiology
https://www.readbyqxmd.com/read/27891610/resveratrol-supplementation-to-high-fat-diet-fed-pregnant-mice-promotes-brown-and-beige-adipocyte-development-and-prevents-obesity-in-male-offspring
#8
Tiande Zou, Daiwen Chen, Qiyuan Yang, Bo Wang, Mei-Jun Zhu, Peter W Nathanielsz, Min Du
Promoting beige/brite adipogenesis and thermogenic activity is considered as a promising therapeutic approach to reduce obesity and metabolic syndrome. Maternal obesity impairs offspring brown adipocyte function and correlates with obesity in offspring. We previously found that dietary resveratrol (RES) induces beige adipocyte formation in adult mice. Here we further evaluated the effect of resveratrol supplementation to pregnant mice on offspring thermogenesis and energy expenditure. Female C57BL/6 J mice were fed a control diet (CON) or a high fat diet (HFD) with/without 0...
November 28, 2016: Journal of Physiology
https://www.readbyqxmd.com/read/27891608/compensatory-axon-sprouting-for-very-slow-axonal-die-back-in-a-transgenic-model-of-spinal-muscular-atrophy-type-iii
#9
Esther Udina, Charles Putman, Luke Harris, N Tyreman, Victoria Cook, Tessa Gordon
Spinal muscular atrophy (SMA) is a common autosomal recessive disorder in humans and is the leading genetic cause of infantile death. Patients lack the SMN1 gene with the severity of the disease depending on the number of copies of the highly homologous SMN2 gene. Although motoneuron death in the Smn+/- transgenic mouse model of mildest form of SMA, SMA type III, has been reported, we have used retrograde tracing of sciatic and femoral motoneurons in the hindlimb with recording of muscle and motor unit isometric forces to count the number of motoneurons with intact neuromuscular connections...
November 28, 2016: Journal of Physiology
https://www.readbyqxmd.com/read/27891607/cortical-and-reticular-contributions-to-human-precision-and-power-grip
#10
Toshiki Tazoe, Monica A Perez
It is well accepted that the corticospinal tract contributes to the control of finger muscles during precision and power grip in humans but the neural mechanisms involved remain poorly understood. Here, we examined motor evoked potentials elicited by cortical and subcortical stimulation of corticospinal axons (MEPs and CMEPs, respectively) and the activity in intracortical circuits (suppression of voluntary electromyography) and spinal motoneurons (F-waves) in an intrinsic hand muscle during index finger abduction (control task), precision grip, and power grip...
November 28, 2016: Journal of Physiology
https://www.readbyqxmd.com/read/27891609/role-of-trpm7-in-cerebral-ischaemia-and-hypoxia
#11
Hong-Shuo Sun
Transient receptor potential melastatin 7 (TRPM7) channel, a calcium-permeable non-selective divalent cation channel, is broadly expressed in various cells and tissues, including the brain. TRPM7 is thought to be coupled to the metabolic state and regulate calcium homeostasis in the cell. TRPM7 takes part in a wide range of cell biology processes that affect cell growth and proliferation, as well as in embryonic development and skeleton formation. TRPM7 plays a significant role in ischaemic and hypoxic brain injury and neuronal cell death...
November 27, 2016: Journal of Physiology
https://www.readbyqxmd.com/read/27883179/evidence-that-an-internal-schema-adapts-swallowing-to-upper-airway-requirements
#12
Seng Mun Wong, Rickie J Domangue, Sidney Fels, Christy L Ludlow
Hyoid and laryngeal movements contribute to laryngeal vestibule closure and upper esophageal sphincter opening during swallowing. Evidence of an internal sensorimotor scaling system allowing individuals to achieve these functional goals is lacking. In speech, speakers adjust their articulatory movement magnitude according to the movement distance required to reach an articulatory target for intelligible speech. We investigated if swallowing is similar in that movement amplitude may be scaled by the functional goal for airway protection during swallowing, rather than by head and neck size...
November 24, 2016: Journal of Physiology
https://www.readbyqxmd.com/read/27880004/causal-relationships-among-neurons-of-the-nucleus-incertus-and-the-hippocampal-theta-activity-in-the-rat
#13
Sergio Martínez-Bellver, Ana Cervera-Ferri, Aina Luque-García, Joana Martínez-Ricós, Alfonso Valverde-Navarro, Manuel Bataller, Juan Guerrero, Vicent Teruel-Marti
In recent years, a body of evidence has shown that the nucleus incertus (NI), in the dorsal tegmental pons, is a key node of the brainstem circuitry involved in hippocampal theta rhythmicity. Ascending reticular brainstem system activation evokes hippocampal theta rhythm with coupled neuronal activity in the NI. In a recent paper, we showed three populations of neurons in the NI with differential firings during hippocampal theta activation. The objective of this work is to better evaluate the causal relationship between the activity of NI neurons and the hippocampus during theta activation in order to further understand the role of the NI in the theta network...
November 23, 2016: Journal of Physiology
https://www.readbyqxmd.com/read/27871127/effect-of-maternal-position-on-fetal-behavioural-state-and-heart-rate-variability-in-healthy-late-gestation-pregnancy
#14
Peter Stone, Wendy Burgess, Jordan McIntyre, Alistair Gunn, Christopher Lear, Laura Bennet, Edwin Mitchell, John Thompson
BACKGROUND: Fetal behavioural states (FBS) are measures of fetal wellbeing. In acute hypoxemia, the human fetus adapts to a lower oxygen consuming state with changes in the cardiotocograph and reduced fetal activity. Recent studies of late gestation stillbirth described the importance of sleep position in the risk of intrauterine death. We designed this study to assess the effects of different maternal positions on FBS in healthy late gestation pregnancies under controlled conditions...
November 21, 2016: Journal of Physiology
https://www.readbyqxmd.com/read/27869319/the-ca-2-sensitizer-ck-2066260-increases-myofibrillar-ca-2-sensitivity-and-submaximal-force-selectively-in-fast-skeletal-muscle
#15
Darren T Hwee, Arthur J Cheng, James J Hartman, Aaron C Hinken, Ken Lee, Nickie Durham, Alan J Russell, Fady I Malik, Håkan Westerblad, Jeffrey R Jasper
Skeletal muscle dysfunction occurs in many diseases and can lead to muscle weakness and premature muscle fatigue. Here we show that the fast skeletal troponin activator, CK-2066260, counteracts muscle weakness by increasing troponin Ca(2+) affinity, thereby increasing myofibrillar Ca(2+) sensitivity. Exposure to CK-2066260 resulted in a concentration-dependent increase in the Ca(2+) sensitivity of ATPase activity in isolated myofibrils and reconstituted hybrid sarcomeres containing fast skeletal muscle troponin C...
November 21, 2016: Journal of Physiology
https://www.readbyqxmd.com/read/27868196/differential-regulation-of-blood-flow-induced-neovascularisation-and-mural-cell-recruitment-by-vegf-and-angiopoietin-signalling
#16
Oliver A Stone, James G Carter, P Charles Lin, Ewa Paleolog, Maria J C Machado, David O Bates
Signalling through VEGF receptors and the Tie2 receptor by angiopoietins is required in combination with blood flow for the formation of a functional vascular network. We tested the hypothesis that VEGF and Ang1 contribute differentially to neovascularization induced by nitric oxide (NO) mediated vasodilatation, by comparing the phenotype of new microvessels in the mesentery during induction of vascular remodelling by over-expression of endothelial nitric oxide synthase (eNOS) in the fat pad of the adult rat mesentery during inhibition of Angiopoietin signalling with soluble Tie2 and VEGF signalling with sFlt1...
November 21, 2016: Journal of Physiology
https://www.readbyqxmd.com/read/27859356/posttranslational-cleavage-of-hv1-in-human-sperm-tunes-ph-and-voltage-dependent-gating
#17
Thomas K Berger, David M Fußhöller, Normann Goodwin, Wolfgang Bönigk, Astrid Müller, Nasim Dokani Khesroshahi, Christoph Brenker, Dagmar Wachten, Eberhard Krause, U Benjamin Kaupp, Timo Strünker
In human sperm, the voltage-gated proton channel Hv1 controls the flux of protons across the flagellar membrane. Here, we show that sperm harbor Hv1 and a shorter isoform, termed Hv1Sper. Hv1Sper is generated from Hv1 by removal of 68 amino acids from the N-terminus by posttranslational proteolytic cleavage. The pH-dependent gating of the channel isoforms is distinctly different. In both Hv1 and Hv1Sper, the conductance-voltage relationship is determined by the pH difference across the membrane (∆pH). However, simultaneous changes in intracellular and extracellular pH that leave ΔpH constant strongly shift the activation curve of Hv1Sper, but not that of Hv1, demonstrating that cleavage of the N-terminus tunes pH sensing in Hv1...
November 17, 2016: Journal of Physiology
https://www.readbyqxmd.com/read/27859335/extracellular-protons-enable-activation-of-the-calcium-dependent-chloride-channel-tmem16a-ano1
#18
Silvia Cruz-Rangel, José J De Jesus-Pérez, Iván A Aréchiga-Figueroa, Aldo A Rodríguez-Menchaca, Patricia Pérez-Cornejo, H Criss Hartzell, Jorge Arreola
TMEM16A (ANO1), the pore forming subunit of a Ca(2+) -dependent Cl(-) channel (CaCC), is activated by direct, voltage-dependent, binding of intracellular Ca(2+) . Endogenous CaCCs are regulated by extracellular protons; however, the molecular basis of such regulation remains unidentified. Here, we evaluated the effects of different extracellular proton concentrations ([H(+) ]o ) on mouse TMEM16A expressed in HEK-293 cells using whole-cell and inside-out patch clamp recordings. We found that increasing the [H(+) ]o from 10(-10) to 10(-5...
November 17, 2016: Journal of Physiology
https://www.readbyqxmd.com/read/27859267/human-motoneurone-excitability-is-depressed-by-activation-of-5ht1a-receptors-with-buspirone
#19
Jessica M D'Amico, Annie A Butler, Martin E Héroux, Florence Cotel, Jean-François M Perrier, Jane E Butler, Simon C Gandevia, Janet L Taylor
Intense serotonergic drive in the turtle spinal cord results in serotonin spillover to the axon initial segment of the motoneurones where it activates 5HT1A receptors and inhibits generation of action potentials. We examined whether activation of 5HT1A receptors decreases motoneurone excitability in humans by determining the effects of a 5HT1A receptor partial agonist, buspirone, on F waves and cervicomedullary motor evoked potentials (CMEPs). In a placebo-controlled double-blind study, 10 participants were tested on two occasions where either placebo or 20 mg buspirone was administered orally...
November 17, 2016: Journal of Physiology
https://www.readbyqxmd.com/read/27859266/spatial-ca-2-profiling-decrypting-the-universal-cytosolic-ca-2-oscillation
#20
Krishna Samanta, Anant B Parekh
Stimulation of cell-surface receptors that couple to phospholipase C to generate the second messenger inositol trisphosphate often evoke repetitive oscillations in cytosolic Ca(2+) . Signalling information is encoded in both the amplitude and frequency of the Ca(2+) spikes. Recent studies have revealed that the spatial profile of the oscillation also imparts signalling power; Ca(2+) microdomains near store-operated CRAC channels in the plasma membrane and inositol trisphosphate-gated channels in the endoplasmic reticulum both signal to distinct downstream targets...
November 17, 2016: Journal of Physiology
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