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Experimental Physiology

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https://www.readbyqxmd.com/read/29450933/face-cooling-reveals-a-relative-inability-to-increase-cardiac-parasympathetic-activation-during-passive-heat-stress
#1
Zachary J Schlader, Morgan C O'Leary, James R Sackett, Blair D Johnson
We tested the hypothesis that passive heat stress attenuates the increase in cardiac parasympathetic stimulation, vascular resistance, and blood pressure evoked by face cooling. During normothermia and when intestinal temperature was elevated by 1.0 ± 0.2°C, eleven healthy young adults underwent 3 min of face cooling. Face cooling was accomplished by placing a 2.5 L bag of ice water (0 ± 0°C) over the cheeks, eyes, and forehead. Primary variables included forehead skin temperature, mean arterial pressure, and systemic, forearm and cutaneous vascular resistances...
February 15, 2018: Experimental Physiology
https://www.readbyqxmd.com/read/29441689/inducible-nitric-oxide-synthase-inhibition-by-1400w-limits-pain-hypersensitivity-in-a-neuropathic-pain-rat-model
#2
C A Staunton, R Barrett-Jolley, L Djouhri, T Thippeswamy
Peripheral neuropathic pain (PNP) resulting from injury or dysfunction to a peripheral nerve, is a major health problem affecting 7-8% of the population. It is inadequately controlled by current drugs, and is characterized by pain hypersensitivity which is believed to be due to sensitization of peripheral and CNS neurons by various inflammatory mediators. Here we examined, in a rat model of PNP: a) whether reducing levels of nitric oxide (NO), with 1400 W, a highly selective inhibitor of inducible NO synthase (iNOS), would prevent/attenuate pain hypersensitivity, and b) the effects of 1400 W on plasma levels of several cytokines that are secreted post iNOS upregulation during chronic pain states...
February 13, 2018: Experimental Physiology
https://www.readbyqxmd.com/read/29436736/psychological-stress-induced-cerebrovascular-dysfunction-the-role-of-metabolic-syndrome-and-exercise
#3
Steven Brooks, Kayla Branyan, Evan DeVallance, Roy Skinner, Kent Lemaster, J Whitney Sheets, Christopher R Pitzer, Shinichi Asano, Randall Bryner, I Mark Olfert, Jefferson C Frisbee, Paul D Chantler
Chronic unresolvable stress leads to the development of depression and cardiovascular disease (CVD). There is a high prevalence of depression with the metabolic syndrome (MetS), however, to what extent the MetS concurrent with psychological stress affects cerebrovascular function is unknown. We investigated the differential effect of MetS on cerebrovascular structure/function in rats (16-17-wk-old) following 8 wk of unpredictable chronic mild stress (UCMS), and whether exercise training could limit any cerebrovascular dysfunction...
February 13, 2018: Experimental Physiology
https://www.readbyqxmd.com/read/29427527/ubc-nepal-expedition-the-use-of-oral-antioxidants-does-not-alter-cerebrovascular-function-at-sea-level-or-high-altitude
#4
Alex B Hansen, Ryan L Hoiland, Nia C S Lewis, Michael M Tymko, Joshua C Tremblay, Michael Stembridge, Daniela Nowak-Flück, Howard H Carter, Damian M Bailey, Philip N Ainslie
Hypoxia is associated with an increased systemic and cerebral formation of free radicals and associated reactants that may be linked to impaired cerebral vascular function a neurological sequela. To what extent oral antioxidants prophylaxis impacts cerebrovascular function in humans throughout the course of acclimatization to the hypoxia of terrestrial high-altitude has not been examined. Thus, the purpose of the current study was to examine the influence of orally ingested antioxidants at clinically relevant doses (vitamin C, E, and alpha-lipoic acid) on cerebrovascular regulation at sea-level (344 m; n = 12; female n = 2 participants), and at high altitude (5050 m; n = 9; female n = 2), in a randomized, placebo-controlled, and double-blinded crossover design...
February 10, 2018: Experimental Physiology
https://www.readbyqxmd.com/read/29405505/sympathetic-vasomotor-activity-during-dynamic-exercise-with-resistive-breathing-sex-differences-and-the-nerve-to-show-it
#5
Ken D O'Halloran
Respiratory muscle metaboreflexes exert substantial influence over cardiorespiratory and autonomic control, exemplified during heavy dynamic exercise in health, and in obstructive airways disease even at rest. This article is protected by copyright. All rights reserved.
February 5, 2018: Experimental Physiology
https://www.readbyqxmd.com/read/29380464/hypothalamic-and-liver-transcriptome-from-two-critical-life-history-stages-in-a-migratory-songbird
#6
Aakansha Sharma, Devraj Singh, Subhajit Das, Vinod Kumar
Very little is understood about genetic mechanisms underlying the onset of spring migration in latitudinal avian migrants. To gain insight into genetic architecture of the hypothalamus and liver tissues of a long-distance migrant, we examined and compared the transcriptome profile of captive night-migratory blackheaded buntings (Emberiza melanocephala) between photoperiodically-induced winter non-migratory (WnM) and spring migratory (SM) life-history states (LHSs) under short and long days, respectively. High-throughput 454 pyrosequenced transcripts were mapped initially with reference to the genome of two phylogenetically close species, Taeniopygia guttata and Ficedula albicollis...
January 29, 2018: Experimental Physiology
https://www.readbyqxmd.com/read/29377377/the-hemodynamic-response-to-incremental-increases-in-negative-intrathoracic-pressure-in-healthy-humans
#7
William S Cheyne, Jinelle C Gelinas, Neil D Eves
Negative intrathoracic pressure (nITP) generally augments venous return and left ventricular (LV) stroke volume (LVSV), though large increases in nITP, commonly seen in respiratory disease, attenuate LVSV. Despite this consistent finding, the degree of nITP required to reduce LVSV and the contributions of series and direct ventricular interaction (DVI) in mediating this response remain unclear. We hypothesized that nITP ≤-15 cmH2 0 would augment LVSV, while nITP ≥-20 cmH2 o would reduce LVSV via DVI and increased afterload...
January 27, 2018: Experimental Physiology
https://www.readbyqxmd.com/read/29377392/chronic-intermittent-hypoxia-and-renovascular-hypertension-a-case-of-one-plus-one-equals-one-half
#8
Ken D O'Halloran
The homeostatic regulation of blood pressure depends on an exquisite interplay between multimodal sensors, several brain regions and long-range control systems that serve to maintain and defend cardiovascular constancy. This article is protected by copyright. All rights reserved.
January 26, 2018: Experimental Physiology
https://www.readbyqxmd.com/read/29363193/cell-shortening-and-calcium-dynamics-in-epicardial-and-endocardial-myocytes-from-the-left-ventricle-of-the-goto-kakizaki-type-2-diabetic-rats
#9
Manal Smail, Lina Al Kury, Muhammad Anwar Qureshi, Anatoliy Shmygol, Murat Oz, Jaipaul Singh, Frank Christopher Howarth
Diabetic cardiomyopathy is considered as one of the major diabetes-associated complications and the pathogenesis of cardiac dysfunction is not well understood. The electromechanical properties of cardiac myocytes vary across the walls of the chambers The aim of this study was to investigate shortening and Ca2+ transport in epicardial (EPI) and endocardial (ENDO) left ventricular myocytes in the Goto-Kakizaki (GK) type 2 diabetic rat heart. Shortening and intracellular Ca2+ transients were measured by video edge detection and fluorescence photometry...
January 24, 2018: Experimental Physiology
https://www.readbyqxmd.com/read/29363240/magnesium-attenuates-endothelin-1-induced-vasoreactivity-and-enhances-vasodilation-in-mouse-pulmonary-arteries-modulation-by-chronic-hypoxic-pulmonary-hypertension
#10
Yun-Ping Mu, Qiu-Hong Huang, Jie-Ling Zhu, Si-Yi Zheng, Fu-Rong Yan, Xiao-Ling Zhuang, James S K Sham, Mo-Jun Lin
Pulmonary hypertension (PH) is characterized by enhanced vasoreactivity and sustained pulmonary vasoconstriction, arising from the aberrant Ca2+ homeostasis in pulmonary arterial smooth muscle cells. In addition to Ca2+ , magnesium, the most abundant intracellular divalent cation, also plays critical roles in many cellular processes that regulate cardiovascular functions. Recent findings suggested that magnesium regulates vascular functions by altering the vascular responses to vasodilator and vasoactive agonists, and affects endothelial function by modulating endothelium-dependent vasodilation in hypertension...
January 23, 2018: Experimental Physiology
https://www.readbyqxmd.com/read/29359403/previous-exposure-to-chronic-intermittent-hypoxia-blunts-the-development-of-one-kidney-one-clip-hypertension-in-rats
#11
Raphael R Perim, Mateus R Amorim, Leni G H Bonagamba, Benedito H Machado
Chronic intermittent hypoxia (CIH) and one-kidney one-clip (1K, 1C) experimental models lead to sympathetic overactivity and hypertension. We hypothesized that previous exposure to CIH potentiates the development of 1K, 1C renal hypertension. Male rats were divided into 4 groups: Control-1K, 1C, maintained under normoxia followed by 1K, 1C surgery (n = 19); Control-Sham, maintained under normoxia, followed by Sham surgery (n = 19); CIH-1K, 1C, exposed to CIH (10 days) and 1K, 1C surgery (n = 19); CIH-Sham, exposed to CIH and Sham surgery (n = 18)...
January 23, 2018: Experimental Physiology
https://www.readbyqxmd.com/read/29349832/effects-of-yoga-interventions-practiced-in-heated-and-thermoneutral-conditions-on-endothelium-dependent-vasodilation-the-bikram-yoga-heart-study
#12
Stacy D Hunter, Jitanan Laosiripisan, Ahmed Elmenshawy, Hirofumi Tanaka
We have previously documented improvements in endothelium-dependent vasodilation with a Bikram (hot) yoga intervention in middle-aged adults. Presently, the effect of environmental temperature in hot yoga on endothelial function is unknown. PURPOSE: The purpose of this investigation was to determine the effects of Bikram yoga interventions performed in the heated and thermoneutral conditions on endothelium-dependent vasodilation. METHODS: Fifty-two sedentary but apparently healthy adults aged 40-60 years were randomly assigned to one of three groups: Bikram yoga practiced at 40...
January 18, 2018: Experimental Physiology
https://www.readbyqxmd.com/read/29349831/aortic-dysfunction-in-metabolic-syndrome-mediated-by-perivascular-adipose-tissue-tnf%C3%AE-and-nox2-dependent-pathway
#13
Evan DeVallance, Kayla W Branyan, Kent Lemaster, I Mark Olfert, David M Smith, Emidio E Pistilli, Jefferson C Frisbee, Paul D Chantler
AIMS: Perivascular adipose tissue (PVAT) is recognized for its vaso-active effects, however it's unclear how Metabolic Syndrome impact thoracic-aorta (t)PVAT and the subsequent effect on functional and structural aortic stiffness. METHODS & RESULTS: Thoracic aorta and tPVAT were removed from 16-17 week old lean (LZR, n = 16) and obese Zucker (OZR, n = 16) rats. OZR presented with aortic endothelial dysfunction, assessed by wire-myography, and increased aortic stiffness, assessed by elastic modulus...
January 18, 2018: Experimental Physiology
https://www.readbyqxmd.com/read/29349824/reduced-left-ventricular-filling-following-blood-volume-extraction-does-not-result-in-compensatory-augmentation-of-cardiac-mechanics
#14
Rachel Lord, David MacLeod, Keith George, David Oxborough, Rob Shave, Mike Stembridge
An acute non-invasive reduction in preload has been shown to augment cardiac mechanics to maintain stroke volume and cardiac output. Such interventions induce concomitant changes in heart rate (HR), whereas blood volume extraction reduces preload without HR changes. Therefore, the purpose of this study was to determine whether a preload reduction in isolation resulted in augmented stroke volume achieved via enhanced cardiac mechanics. Nine healthy volunteers (4 female, age 29 ± 11 years) underwent echocardiography for the assessment of left ventricular (LV) volumes and mechanics in a supine position at baseline and end-extraction following the controlled removal of 25% of total blood volume (1062 ± 342 ml)...
January 18, 2018: Experimental Physiology
https://www.readbyqxmd.com/read/29345432/getting-published
#15
EDITORIAL
Mike Tipton
Publications remain an important part of the currency of academia, they are intimately related to your professional standing, advancement and funding. This article is protected by copyright. All rights reserved.
January 18, 2018: Experimental Physiology
https://www.readbyqxmd.com/read/29345019/a-vascular-mechanism-to-explain-thermally-mediated-variations-in-deep-body-cooling-rates-during-the-immersion-of-profoundly-hyperthermic-individuals
#16
Joanne N Caldwell, Anne M J van den Heuvel, Pete Kerry, Mitchell J Clark, Gregory E Peoples, Nigel A S Taylor
Physiologically trivial time differences for cooling the intrathoracic viscera of hyperthermic individuals have been reported between cold- and temperate-water immersion treatments. One explanation for that observation is reduced convective heat delivery to the skin during cold immersion, and this experiment was designed to test both the validity of that observation, and its underlying hypothesis. Eight healthy males participated in four head-out, water immersions: two when normothermic, and two following exercise-induced, moderate-profound hyperthermia...
January 18, 2018: Experimental Physiology
https://www.readbyqxmd.com/read/29336094/sympathetic-neurovascular-regulation-during-pregnancy-a-longitudinal-case-series-study
#17
Laura M Reyes, Charlotte W Usselman, Rachel J Skow, Nisha Charkoudian, Jeffery S Staab, Margie H Davenport, Craig D Steinback
The adaptations of sympathetic nerve activity (SNA) during pregnancy remain poorly understood. An increase in blood volume, cardiac output (Q) and SNA with a concomitant drop in total peripheral resistance (TPR), suggest that during pregnancy there is a reduced transduction of SNA into TPR. Most of these findings have originated from cross-sectional studies, thus, we conducted a longitudinal assessment of SNA and TPR in two participants. Measures were made pre-pregnancy (early follicular phase), four occasions during pregnancy, and at two-months postpartum...
January 16, 2018: Experimental Physiology
https://www.readbyqxmd.com/read/29334157/elevated-sympathetic-vasomotor-outflow-in-response-to-increased-inspiratory-muscle-activity-during-exercise-is-less-in-young-women-compared-with-men
#18
Keisho Katayama, Joshua R Smith, Kanako Goto, Kaori Shimizu, Mitsuru Saito, Koji Ishida, Teruhiko Koike, Satoshi Iwase, Craig A Harms
We compared changes in muscle sympathetic nerve activity (MSNA) and cardiovascular variables during leg cycle exercise with increased inspiratory muscle resistance in men and women. We hypothesized that sympathetic vasomotor outflow during exercise with increased inspiratory resistance would be attenuated in young women compared with age-matched men. Eight women and seven men completed the study. The subjects performed two 10-min exercise bouts at 40% peak oxygen uptake using a cycle ergometer in a semirecumbent position [spontaneous breathing for 5 min and voluntary hyperventilation with or without inspiratory resistive breathing for 5 min (breathing frequency: 50 breaths min-1 with a 50% duty cycle, inspiratory resistance: 30% of maximal inspiratory pressure)]...
January 15, 2018: Experimental Physiology
https://www.readbyqxmd.com/read/29330891/why-do-african-american-have-a-higher-risk-for-cerebral-disease
#19
Shigehiko Ogoh
Clinical and epidemiological studies have reported significant racial differences in cardiovascular (CVD) and metabolic disease including hypertension, stroke, atherosclerosis, and type II diabetes which is most prevalent in the African American population. This article is protected by copyright. All rights reserved.
January 12, 2018: Experimental Physiology
https://www.readbyqxmd.com/read/29327381/oxidative-stress-impairs-myocyte-autophagy-resulting-in-myocyte-hypertrophy
#20
Jia-Pu Wang, Rui-Fang Chi, Ke Wang, Teng Ma, Xiao-Fei Guo, Xiao-Li Zhang, Bao Li, Fu-Zhong Qin, Xue-Bin Han, Bian-Ai Fan
Insufficient or excessive myocyte autophagy is associated with left ventricular (LV) hypertrophy. Reactive oxygen species mediate myocyte hypertrophy in vitro and pressure overload-induced LV hypertrophy in vivo. In the present study, we tested the hypothesis that oxidative stress induces autophagy impairment that results in myocyte hypertrophy. H9C2 cardiomyocytes were exposed to 10 and 50 μm hydrogen peroxide (H2 O2 ) for 48 h pretreated with autophagy inhibitor 3-methyladenine (3-MA). Male Sprague-Dawley rats underwent abdominal aortic constriction (AAC) or sham operation...
January 12, 2018: Experimental Physiology
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