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Experimental Physiology

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https://www.readbyqxmd.com/read/28439921/impact-of-obstructive-sleep-apnoea-and-intermittent-hypoxia-on-cardiovascular-and-cerebrovascular-regulation
#1
Andrew E Beaudin, Xavier Waltz, Patrick J Hanly, Marc J Poulin
Obstructive sleep apnoea (OSA) is associated with increased risk of cardiovascular and cerebrovascular disease, a consequence attributed in part to chronic intermittent hypoxia (IH) resulting from repetitive apnoeas during sleep. Although findings from experimental animal, and human, models have shown that IH is detrimental to vascular regulation, the severity of IH used in many of these animal studies (e.g. inspired fraction of oxygen (FI O2 ) = 2-3%; oxygen desaturation index (ODI) = 120 events h(-1) ) is considerably greater than that observed in the majority of patients with OSA...
April 24, 2017: Experimental Physiology
https://www.readbyqxmd.com/read/28436589/short-chain-fatty-acids-augment-rat-duodenal-mucosal-barrier-function
#2
Wan Salman Wan Saudi, Markus Sjöblom
Short-chain fatty acids (SCFAs) are produced by bacterial fermentation in the large intestine, particularly from diets containing fibres and carbohydrates. The small intestinal epithelium is exposed to SCFAs derived mainly from oral bacteria or food supplementation. Although luminal nutrients are important in regulation of intestinal functions the role of SCFAs in regulation of small intestinal mucosal barrier function and motility has not been fully described. The aim of the present study was to elucidate the effects of acetate and propionate on duodenal mucosal barrier function and motility...
April 24, 2017: Experimental Physiology
https://www.readbyqxmd.com/read/28436207/racial-differences-in-the-association-between-heart-rate-variability-and-left-ventricular-mass
#3
LaBarron K Hill, Lana L Watkins, Alan L Hinderliter, James A Blumenthal, Andrew Sherwood
PURPOSE: Increased left ventricular mass (LVM) is an early precursor of target organ damage due to hypertension. Diminished parasympathetic cardiac control has been linked to both hypertension onset and left ventricular impairment; however, emerging evidence suggests that this pattern may be different in African Americans. The present study sought to determine if race impacts the relationship between parasympathetic cardiac control and LVM. METHODS: LVM was assessed via echocardiography in a sample (N = 148) of African American and White adults (Mean age = 33...
April 24, 2017: Experimental Physiology
https://www.readbyqxmd.com/read/28436171/sex-and-regional-differences-in-rabbit-right-ventricular-l-type-calcium-current-levels-and-mathematical-modeling-of-arrhythmia-vulnerability
#4
Zane M Kalik, Joshua L Mike, Cassandra Slipski, Moriah Wright, Jozsi Z Jalics, Mark D Womble
Previous studies have shown that adult rabbit left ventricular myocytes exhibit sex and regional differences in L-type calcium current (ICa-L ) levels that contribute to increased susceptibility to arrhythmogenic early afterdepolarizations (EADs). We used patch clamp recordings from isolated adult male and female rabbit right ventricular myocytes to determine apex-base differences in ICa-L density, and mathematical modeling to examine ICa-L contribution to EAD formation. Current density measured at 0 mV in female base myocytes was 67% higher than male base myocytes and 55% higher than female apex myocytes...
April 24, 2017: Experimental Physiology
https://www.readbyqxmd.com/read/28436159/the-mechanism-research-of-hypoxia-induced-increased-late-sodium-current-resulting-in-intracellular-ca-2-overload-in-ventricular-myocytes
#5
Chen Fu, Jie Hao, Mengliu Zeng, Yejia Song, Wanzhen Jiang, Peihua Zhang, Antao Luo, Zhenzhen Cao, Luiz Belardinelli, Jihua Ma
Hypoxia leads to augmentation of late sodium current (INa.L ) and cellular Na(+) loading, increased reverse Na(+) -Ca(2+) exchange current (reverse INCX ) and intracellular Ca(2+) loading in rabbit ventricular myocytes. The purpose of this study was to determine the intracellular signal transduction pathways involved in the modulation of INa.L during hypoxia in ventricular myocytes. Whole-cell and cell-attached patch clamp techniques were used to record INa.L , and the whole-cell mode was also used to record reverse INCX and to study intercellular signal transduction mechanisms that mediate the increased INa...
April 24, 2017: Experimental Physiology
https://www.readbyqxmd.com/read/28436061/resistance-exercise-reduces-memory-impairment-induced-by-monosodium-glutamate-in-male-and-female-rats
#6
Paulo Cesar Oliveira Araujo, Caroline Brandão Quines, Natália Silva Jardim, Marlon Regis Leite, Cristina Wayne Nogueira
NEW FINDINGS: Monosodium glutamate causes cognitive impairment. Resistance exercise is effective against monosodium glutamate induced memory impairment in male and female mice. ABSTRACT: Monosodium glutamate (MSG), a flavor enhancer in diets, causes cognitive impairment in humans. Exercise has been reported to protect against impairment of memory in humans. This study investigated if resistance exercise improves the performance of male and female rats treated with MSG in tests of memory and motor coordination...
April 23, 2017: Experimental Physiology
https://www.readbyqxmd.com/read/28397383/passive-heat-stress-reduces-circulating-endothelial-and-platelet-microparticles
#7
Anthony R Bain, Philip N Ainslie, Tyler D Bammert, Jamie G Hijmans, Mypinder Sekhom, Ryan L Hoiland, Daniela Flück, Joseph Donnelly, Christopher A DeSouza
Interest in circulating endothelial- (EMPs) and platelet- (PMPs) derived microparticles has increased due to their potential pathogenic role in vascular disease and as biomarkers for vascular health. Hyperthermia is commonly associated with a proinflammatory stress, but may also provide vascular protection when the temperature elevation is non-pathological. Circulating microparticles may contribute to the cellular adjustments and resultant vascular impacts of hyperthermia. Here, we determined whether circulating concentrations of arterial EMPs and PMPs are altered by passive heat stress (+2°C esophageal temperature)...
April 11, 2017: Experimental Physiology
https://www.readbyqxmd.com/read/28397384/characteristics-and-effectiveness-of-vasodilatory-and-pressor-compensation-for-reduced-relaxation-time-during-rhythmic-forearm-contractions
#8
Robert F Bentley, Veronica J Poitras, Terrence Hong, Michael E Tschakovsky
During muscle contraction in rhythmic exercise muscle blood flow is significantly impeded by microvascular compression. The purpose of this study was to establish the nature and magnitude of vasodilatory and/or pressor compensatory responses during forearm exercise in the face of an increased duration of mechanical microvascular compression, and whether the effectiveness of such compensation was exercise intensity dependent. Seven healthy males (21.0 ± 1.8 yrs) completed progressive forearm exercise (24...
April 10, 2017: Experimental Physiology
https://www.readbyqxmd.com/read/28393420/high-adventure-shunts-old-notions-of-pulmonary-vascular-control-during-hypoxic-exercise-contrasting-views-that-might-just-burst-your-bubble
#9
Ken D O'Halloran
In the absence of intracardiac shunt, the entire cardiac output embraces the lungs through the pulmonary vascular system. This article is protected by copyright. All rights reserved.
April 10, 2017: Experimental Physiology
https://www.readbyqxmd.com/read/28393459/lunhab-interactive-effects-of-a-10-day-sustained-exposure-to-hypoxia-and-bedrest-on-aerobic-exercise-capacity-in-male-lowlanders
#10
Michail E Keramidas, Igor B Mekjavic, Ola Eiken
The study examined the interactive effects of a 10-day exposure to hypoxia and bedrest on the whole body peak oxygen uptake (V˙O2 peak ) during maximal exercise, and on skeletal-muscle and cerebral oxygenation during submaximal exercise. Nine males underwent three 10-day confinements, in a Latin-square order: (i) a normoxic bedrest [NBR; partial pressure of inspired O2 (PI O2 ) = 134.2 ± 0.7 mmHg], (ii) a hypoxic bedrest (HBR; PI O2  = 102.9 ± 0.1 mmHg at day 1, 91.5 ± 1.2 mmHg at days 3-10), and (iii) a hypoxic ambulation (HAMB; PI O2 as in HBR)...
April 9, 2017: Experimental Physiology
https://www.readbyqxmd.com/read/28390080/changes-in-acute-pulmonary-vascular-responsiveness-to-hypoxia-during-a-progressive-ascent-to-high-altitude-5-300%C3%A2-m
#11
Andrew M Luks, Denny Levett, Daniel S Martin, Christopher Goss, Kay Mitchell, Bernadette O Fernandez, Martin Feelisch, Michael P Grocott, Erik R Swenson
We sought to determine whether changes in pulmonary artery pressure responses to hypoxia suggestive of vascular remodeling occur during progressive exposure to high altitude and whether such alterations are related to changes in concentrations of circulating biomarkers with known or suspected actions on the pulmonary vasculature during ascent. We measured tricuspid valve transvalvular pressure gradients (TVPG) in healthy volunteers breathing air at sea level (London, UK) and under hypoxic conditions simulating the PI O2 at two locations in Nepal, Namche Bazaar (NB, elevation 3,500 m) and Everest Base Camp (EBC, elevation 5,300 m)...
April 8, 2017: Experimental Physiology
https://www.readbyqxmd.com/read/28383821/h2-s-induced-gastric-fundus-smooth-muscle-tension-potentiation-is-mediated-by-the-pi3-k-akt-enos-pathway
#12
Xiang-Min Meng, Xu Huang, Hong-Li Lu, Chun-Mei Zhang, Young-Chul Kim, Jie Chen, Wen-Xie Xu
Hydrogen sulfide (H2 S) is considered a new gasotransmitter, along with NO and CO. It was recently confirmed that H2 S and NO play important roles in regulating gastrointestinal smooth muscle tension. The present study was designed to elucidate the interactions between H2 S and NO with respect to gastric fundus smooth muscle tension regulation using western blotting, physiology and electrochemistry techniques. Real-time H2 S and NO generation was detected in gastric smooth muscle tissue. NaHS, an H2 S donor, enhanced fundus smooth muscle tension, while SNP, an NO donor, decreased fundus smooth muscle tension in a dose-dependent manner...
April 6, 2017: Experimental Physiology
https://www.readbyqxmd.com/read/28382753/designing-translationally-relevant-pre-clinical-studies-of-novel-therapeutics
#13
Dominic J Wells
In this issue of Experimental Physiology. This article is protected by copyright. All rights reserved.
April 6, 2017: Experimental Physiology
https://www.readbyqxmd.com/read/28382735/michael-j-rennie-a-perspective-on-a-scientist-who-life-s-work-helped-sculpt-knowledge-about-the-regulation-of-the-muscloskeletal-system-by-nutrition-exercise-and-inactivity
#14
Philip J Atherton, Ken Smith
In 2005, Michael (Mike) J Rennie MSc, PhD, FRSE was awarded the G. L. Brown Prize Lecture. This article is protected by copyright. All rights reserved.
April 6, 2017: Experimental Physiology
https://www.readbyqxmd.com/read/28374427/-sustainable-shear-a-new-approach-for-assessment-of-lower-limb-vascular-function
#15
Walter Wray
Since the development of the flow-mediated vasodilation (FMD) test by Celermajer et al. in 1992, vascular physiologists the world over have sought to develop and refine non-invasive assessments of endothelium-dependent vasodilation in humans This article is protected by copyright. All rights reserved.
April 4, 2017: Experimental Physiology
https://www.readbyqxmd.com/read/28370799/through-modulation-of-cardiac-ca-2-handling-ucp2-affects-cardiac-electrophysiology-and-influences-the-susceptibility-for-ca-2-mediated-arrhythmias
#16
Robert Larbig, Sara Reda, Vera Paar, Andrea Trost, Johannes Leitner, Stephanie Weichselbaumer, Karolina A Motloch, Bernhard Wernly, Andreas Arrer, Benjamin Strauss, Michael Lichtenauer, Herbert A Reitsamer, Lars Eckardt, Guiscard Seebohm, Uta C Hoppe, Lukas J Motloch
Introduction UCP2 belongs to a superfamily of mitochondrial ion transporters. Due to its beneficial influence on production of reactive oxygen species it is suggested to reduce cardiac ischemic reperfusion injury. Recent studies uncovered its ability to regulate mitochondrial Ca(2+) -uptake and therefore to influence cardiac cytosolic Ca(2+) -handling, indicating compensatory pathways to avoid toxic Ca(2+) -overload in UCP2 knock-out mice (UCP2(-/-) ). However, the specific mechanisms and their impact on cardiac electrophysiology remain speculative...
March 31, 2017: Experimental Physiology
https://www.readbyqxmd.com/read/28370674/reduced-blood-flow-through-intrapulmonary-arteriovenous-anastomoses-during-exercise-in-lowlanders-during-acclimatization-to-high-altitude
#17
Lindsey M Boulet, Andrew T Lovering, Michael M Tymko, Trevor A Day, Mike Stembridge, Trang Anh Nguyen, Philip N Ainslie, Glen E Foster
Blood flow through intrapulmonary arteriovenous anastomoses (Q̇IPAVA ) is elevated during exercise at sea level (SL) and at rest in acute normobaric hypoxia. Following high altitude (HA) acclimatization, resting Q̇IPAVA is similar to SL, but it is unknown if this is true during exercise at HA. We reasoned that exercise at HA (5,050 m) would exacerbate Q̇IPAVA due to heightened pulmonary arterial pressure. Using a supine cycle ergometer, seven healthy adults free from intracardiac shunts underwent an incremental exercise test at SL (25, 50, 75% of SL V̇O2peak ) and at HA (25, 50% of SL V̇O2peak )...
March 30, 2017: Experimental Physiology
https://www.readbyqxmd.com/read/28303677/examination-of-crispr-cas9-design-tools-and-the-effect-of-target-site-accessibility-on-cas9-activity
#18
Ciaran M Lee, Timothy H Davis, Gang Bao
The recent adaptation of the CRISPR/Cas9 system for targeted genome engineering has led to its widespread applications in many fields worldwide. In order to better understand the design rules of CRISPR/Cas9 systems, several groups have carried out large library-based screens leading to some insight into sequence preferences among highly active target sites. To facilitate CRISPR/Cas9 design these studies have spawned a plethora of gRNA design tools with algorithms based solely on direct or indirect sequence features...
March 16, 2017: Experimental Physiology
https://www.readbyqxmd.com/read/28294453/a-translational-approach-for-nmda-receptor-profiling-as-a-vulnerability-biomarker-for-depression-and-schizophrenia
#19
Handan Gunduz-Bruce, Joshua Kenney, Suravi Changlani, Aldo Peixoto, Ralitza Gueorguieva, Cheryl Leone, Nina Stachenfeld
Altered N-methyl-D-aspartate (NMDA) receptor activity and glutamate signaling may underlie the pathogenesis of both schizophrenia and depression in subgroups of patients. In schizophrenia, pharmacologic modeling, postmortem and imaging data suggest reduced NMDA signaling. In contrast, recent clinical trials demonstrating the efficacy of the NMDA antagonist ketamine in severely depressed patients suggest increased NMDA receptor signaling. We conducted a proof of concept study to assess whether there is any in vivo evidence for an inverse association in depression and schizophrenia with respect to the NMDA receptor function...
March 13, 2017: Experimental Physiology
https://www.readbyqxmd.com/read/28295786/stat3-potentiates-the-ability-of-airway-smooth-muscle-cells-to-promote-angiogenesis-by-regulating-vegf-signaling
#20
Jing Lv, Baohua Sun, Zhitao Mai, Mingming Jiang, Junfeng Du
Airway angiogenesis indicates the specific vascular structure remodeling that occurs in asthma. Airway smooth muscle (ASM) cells have been reported to be capable of promoting airway angiogenesis; however, the potential mechanism is yet not fully defined. Herein, we investigated the role of signal transducer and activator of transcription 3 (STAT3), in the progress of airway angiogenesis. Western blot analysis showed that STAT3 activation was aberrantly up-regulated in ASM tissues of patients with asthma and ASM cells that were exposed to cytokines to imitate the airway conditions in patients with asthma...
March 10, 2017: Experimental Physiology
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