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American Journal of Physiology. Regulatory, Integrative and Comparative Physiology

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https://www.readbyqxmd.com/read/27903516/metabolic-abnormalities-and-obesity-s-impact-on-the-risk-for-developing-preeclampsia
#1
Frank T Spradley
Preeclampsia (PE), a hypertensive disorder of pregnancy, is increasing as a major contributor to perinatal and long-term morbidity of mother and offspring. PE is thought to originate from ischemic insults in the placenta driving the release of pro-hypertensive anti-angiogenic (sFlt-1) and pro-inflammatory (TNFα) factors into the maternal circulation. While the increased incidence of PE is hypothesized to be largely due to the obesity pandemic, the mechanisms whereby obesity increases this risk are unknown...
November 30, 2016: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/27903515/passive-heat-acclimation-improves-skeletal-muscle-contractility-in-humans
#2
Sebastien Racinais, Mathew G Wilson, Julien D Périard
The aim of this study was to investigate the effect of repeated passive heat exposure (i.e. acclimation) on muscle contractility in humans. Fourteen non-heat acclimated males completed two trials including electrically evoked twitches and voluntary contractions in thermoneutral conditions (COOL: 24ºC, 40% RH) and hot ambient conditions in the hyperthermic state (HOT: 44-50ºC, 50% RH) on consecutive days in a counterbalanced order. Rectal temperature was ~36.5ºC in COOL and was maintained at ~39ºC throughout HOT...
November 30, 2016: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/27903514/do-high-salt-microenvironments-drive-hypertensive-inflammation
#3
Jason D Foss, Annet Kirabo, David G Harrison
Hypertension is a global epidemic affecting over one billion people worldwide. Despite this, the etiology of most cases of human hypertension remains obscure and treatment remains suboptimal. Excessive dietary salt and inflammation are known contributors to the pathogenesis of this disease. Recently, it has been recognized that salt can accumulate in the skin and skeletal muscle producing concentrations of sodium greater than the plasma in hypertensive animals and humans. Such elevated levels of sodium have been shown to alter immune cell function...
November 30, 2016: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/27903513/the-maximum-heart-rate-in-brown-trout-salmo-trutta-fario-is-not-limited-by-firing-rate-of-pacemaker-cells
#4
Jaakko Haverinen, Denis V Abramochkin, Andre Kamkin, Matti Vornanen
Temperature-induced changes in cardiac output (Q) in fish are largely dependent on thermal modulation of heart rate (fH) and at high temperatures Q collapses due to heat-dependent depression of fH This study tests the hypothesis that firing rate of sinoatrial pacemaker cells sets the upper thermal limit of fH in vivo. To this end temperature-dependence of action potential (AP) frequency of enzymatically isolated pacemaker cells (pacemaker rate, fPM), spontaneous beating rate of isolated sinoatrial preparations (fSA) and in vivo heart rate (fH) of the cold-acclimated (4°C) brown trout (Salmo trutta fario) were compared under acute thermal challenges...
November 30, 2016: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/27903512/thyroid-hormone-stimulated-increases-in-pgc-1%C3%AE-and-ucp2-promote-life-history-specific-endocrine-changes-and-maintain-a-lipid-based-metabolism
#5
Bridget Martinez, José G Soñanez-Organis, Jose A Godoy-Lugo, Lillian Horin, Daniel E Crocker, Rudy M Ortiz
Thyroid hormones (TH) regulate metabolism, but are typically suppressed during times of stressful physiological conditions, including fasting. Interestingly, prolonged fasting in northern elephant seal pups is associated with reliance on a lipid-based metabolism and increased levels of circulating thyroid hormones that are partially attributed to active secretion as opposed to reduced clearance. This apparent paradox is coupled with complementary increases in cellular TH-mediated activity suggesting that in mammals naturally adapted to prolonged fasting TH are necessary to support metabolism...
November 30, 2016: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/27903511/cardiac-remodeling-and-increased-central-venous-pressure-underlie-elevated-stroke-volume-and-cardiac-output-of-seawater-acclimated-rainbow-trout
#6
Jeroen Brijs, Erik Sandblom, Esmée Dekens, Joacim Näslund, Andreas Ekström, Michael Axelsson
Substantial increases in cardiac output (CO), stroke volume (SV) and gastrointestinal blood flow are essential for euryhaline rainbow trout (Oncorhyncus mykiss) osmoregulating in seawater. However, the underlying hemodynamic mechanisms responsible for these changes are unknown. By examining a range of circulatory and cardiac morphological variables of seawater- and freshwater-acclimated rainbow trout, the present study revealed a significantly higher central venous pressure (CVP) in seawater-acclimated trout (~0...
November 30, 2016: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/27903510/vitamin-d-supplementation-reduces-some-at1-aa-induced-downstream-targets-implicated-in-preeclampsia-including-hypertension
#7
Jessica L Faulkner, Lorena M Amaral, Denise C Cornelius, Mark W Cunningham, Tarek Ibrahim, Autumn Heep, Nathan Campbell, Nathan Usry, Kedra Wallace, Florian Herse, Ralf Dechend, Babbette D LaMarca
Autoantibodies to the angiotensin II (ANGII) type I receptor (AT1-AA) are associated with preeclampsia (PE). We found that Vitamin D supplementation reduced AT1-AA and blood pressure (MAP) in the RUPP rat model of PE. However, it was undetermined if the decrease in AT1-AA was the mechanism whereby Vitamin D lowered MAP or if it was through factors downstream of AT1-AA. Uterine artery resistance index, placental ET-1 and sFlt-1 are increased with AT1-AA induced hypertension and considered markers of PE in pregnant women...
November 30, 2016: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/27881400/loss-of-ucp1-exacerbates-western-diet-induced-glycemic-dysregulation-independent-of-changes-in-body-weight-in-female-mice
#8
Nathan C Winn, Victoria J Vieira-Potter, Michelle L Gastecki, Rebecca J Welly, Rebecca J Scroggins, Terese M Zidon, T'Keaya L Gaines, Makenzie L Woodford, Natalia G Karasseva, Jill A Kanaley, Harold S Sacks, Jaume Padilla
We tested the hypothesis that female mice null for UCP1 would have increased susceptibility to Western diet-induced "whitening" of brown adipose tissue (AT) and glucose intolerance. Six-week old C57BL/6J wild-type (WT) and UCP1 knockout (UCP1(-/-)) mice, housed at 25°C, were randomized to either a control diet (10% kcal from fat) or Western diet (45% kcal from fat and 1% cholesterol) for 28 weeks. Loss of UCP1 had no effect on energy intake, energy expenditure, spontaneous physical activity, weight gain, or visceral white AT mass...
November 23, 2016: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/27881399/intradermal-administration-of-endothelin-1-attenuates-endothelium-dependent-and-independent-cutaneous-vasodilation-via-rho-kinase-in-young-adults
#9
Naoto Fujii, Tatsuro Amano, Lyra Halili, Jeffrey C Louie, Sarah Yan Zhang, Brendan D McNeely, Glen P Kenny
We recently showed that intradermal administration of endothelin-1 diminished endothelium-dependent and -independent cutaneous vasodilation. We evaluated the hypothesis that Rho kinase may be a mediator of this response. We also sought to evaluate if endothelin-1 increases sweating. In twelve adults (25±6 years), we measured cutaneous vascular conductance (CVC) and sweating during 1) endothelium-dependent vasodilation induced via administration of incremental doses of methacholine (0.25, 5, 100, 2000mM each for 25 min) and 2) endothelium-independent vasodilation induced via administration of 50mM sodium nitroprusside (20-25 min)...
November 23, 2016: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/27881398/separate-and-shared-sympathetic-outflow-to-white-and-brown-fat-coordinately-regulate-thermoregulation-and-beige-adipocyte-recruitment
#10
Ngoc Ly T Nguyen, Candace L Barr, Vitaly Ryu, Qiang Cao, Bingzhong Xue, Timothy J Bartness
White adipose tissue (WAT) and brown adipose tissue (BAT) are innervated and regulated by the sympathetic nervous system (SNS). It is not clear, however, whether there are shared or separate central SNS outflows to WAT and BAT that regulate their function. We injected two isogenic strains of pseudorabies virus, a retrograde transneuronal viral tract tracer, with unique fluorescent reporters into interscapular BAT (IBAT) and inguinal WAT (IWAT) of the same Siberian hamsters to define SNS pathways to both. To test the functional importance of SNS coordinated control of BAT and WAT, we exposed hamsters with denervated SNS nerves to IBAT to 4°C for 16-24 hours, and measured core and fat temperatures, and norepinephrine turnover (NETO) and uncoupling protein 1 (UCP1) expression in fat tissues...
November 23, 2016: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/27856415/aerobic-system-analysis-based-on-oxygen-uptake-and-hip-acceleration-during-random-over-ground-walking-activities
#11
Thomas Beltrame, Richard L Hughson
Deteriorated aerobic response to moderate exercise might precede the manifestation of clinical symptoms of non-communicable diseases. The purpose of the current study was to verify that the use of current wearable technologies for analysis of pulmonary oxygen uptake (VO2) dynamics during a pseudorandom ternary sequence (PRTS) over-ground walking protocol is a suitable procedure for the investigation of the aerobic response in more realistic settings. A wearable accelerometer assessed the input changes delivered to the aerobic system...
November 16, 2016: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/27856414/neurovascular-control-of-blood-pressure-is-influenced-by-aging-sex-and-sex-hormones
#12
Sarah Elizabeth Baker, Jacqueline K Limberg, Sushant M Ranadive, Michael J Joyner
In this review, we highlight that the relationship between muscle sympathetic nerve activity (MSNA) and mean arterial pressure is complex, differs by sex, and changes with age. In young men there is an inverse relationship between MSNA and cardiac output where high MSNA is compensated for by low cardiac output. This inverse relationship is not seen in older men. In young women sympathetic vasoconstriction is offset by β-adrenoreceptor mediated vasodilation, limiting the ability of young women to maintain blood pressure in response to orthostatic stress...
November 16, 2016: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/27834292/mesenteric-vascular-dysregulation-and-intestinal-inflammation-accompanies-experimental-spinal-cord-injury
#13
Emily M Besecker, Gina M Deiter, Nicole Pironi, Timothy K Cooper, Gregory Michael Holmes
Cervical and high thoracic spinal cord injury (SCI) drastically impairs autonomic nervous system function. Individuals with SCI at thoracic spinal-level 5 (T5) or higher often present cardiovascular disorders that include resting systemic arterial hypotension. Gastrointestinal (GI) tissues are critically dependent upon adequate blood flow and even brief periods of visceral hypoxia triggers GI dysmotility. The aim of this study was to test the hypothesis that T3-SCI induces visceral hypoperfusion, diminished postprandial vascular reflexes and concomitant visceral inflammation...
November 9, 2016: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/27834291/sex-differences-in-the-metabolic-dysfunction-and-insulin-resistance-of-skeletal-muscle-glucose-transport-following-high-fructose-ingestion
#14
Yupaporn Rattanavichit, Natsasi Chukijrungroat, Vitoon Saengsirisuwan
The role of high fructose ingestion (HFI) in the development of conditions mimicking human metabolic syndrome has mostly been demonstrated in male animals; however, the extent of HFI-induced metabolic alterations in females remains unclear. The present study investigated whether HFI-induced metabolic perturbations differ between sexes and whether HFI aggravates the metabolic disturbances under ovarian hormone deprivation. Male, female and ovariectomized (OVX) Sprague-Dawley rats were given either water or liquid fructose (10% w/v) for 6 weeks...
November 9, 2016: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/27834290/altered-muscle-satellite-cell-activation-following-16-weeks-of-resistance-training-in-young-men
#15
Joshua P Nederveen, Tim Snijders, Sophie Joanisse, Christopher G Wavell, Cameron J Mitchell, Leeann M Johnston, Steven K Baker, Stuart M Phillips, Gianni Parise
Skeletal muscle satellite cells (SC) play an important role in muscle adaptation. In untrained individuals, SC content and activation status has been observed to increase in response to a single bout of exercise. Muscle fiber characteristics change considerably when resistance exercise is performed chronically, but whether training status affects the activity of SC in response to a single bout of exercise remains unknown. We examined the changes in SC content and activation status following a single bout of resistance exercise, prior to and following a 16wk progressive resistance training (RT) program in fourteen young (25±3yr) men...
November 9, 2016: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/27834289/the-metabolic-effects-of-prazosin-on-skeletal-muscle-insulin-resistance-in-glucocorticoid-treated-male-rats
#16
Emily C Dunford, Erin R Mandel, Sepideh Mohajeri, Tara L Haas, Michael C Riddell
High dose glucocorticoids (GC) induce skeletal muscle atrophy, insulin resistance and reduced muscle capillarization. Identification of treatments to prevent or reverse capillary rarefaction and metabolic deterioration caused by prolonged elevations in GCs would be therapeutically beneficial. Chronic administration of prazosin, α1-adrenergic antagonist, increases skeletal muscle capillarization, in healthy rodents and recently, a rodent model of elevated GCs and hyperglycemia. The purpose of this study was to determine whether prazosin administration would improve glucose tolerance and insulin sensitivity, through prazosin mediated sparing of capillary rarefaction, in this rodent model of increased GC exposure...
November 9, 2016: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/27806985/high-fat-diet-induced-glucose-dysregulation-is-independent-of-changes-in-islet-ace2-in-mice
#17
Harshita Chodavarapu, Kavaljit H Chhabra, Huijing Xia, Vinayak Shenoy, Xinping Yue, Eric Lazartigues
While restoration of ACE2 activity in the pancreas leads to improvement of glycemia in experimental models of type 2 diabetes, global deficiency in ACE2 disrupts β-cell function and impairs glucose tolerance in mice, demonstrating the physiological role of ACE2 in glucose homeostasis. Although the contribution of pancreatic ACE2 to glucose regulation has been demonstrated in genetic models of diabetes and in models with overexpression of the renin-angiotensin system (RAS), it is unclear whether islet ACE2 is involved in glycemic control in common models of human type 2 diabetes...
November 2, 2016: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/27806984/dietary-%C3%AE-linolenic-acid-supplementation-alters-skeletal-muscle-plasma-membrane-lipid-composition-sarcolemmal-fat-cd36-abundance-and-palmitate-transport-rates
#18
Zane Chorner, Pierre-Andre Barbeau, Laura Castellani, David C Wright, Adrian Chabowski, Graham P Holloway
The cellular processes influenced by consuming polyunsaturated fatty acids remains poorly defined. Within skeletal muscle, a rate-limiting step in fatty acid oxidation is the of movement lipids across the sarcolemmal membrane, and therefore we aimed to determine the effects of consuming Flaxseed oil high in α-linolenic acid (ALA), on plasma membrane lipid composition and the capacity to transport palmitate. Rats fed a diet supplemented with ALA (10%) displayed marked increases in n-3 PUFAs within whole muscle and sarcolemmal membranes (~5-fold), at the apparent expense of arachidonic acid (-50%)...
November 2, 2016: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/27806983/the-protective-effect-of-apolipoprotein-in-models-of-trophoblast-invasion-and-preeclampsia
#19
Francesca Charlton, Gabriele Bobek, Tim Stait-Gardner, William S Price, Katrina Maree Mirabito Colafella, Bei Xu, Angela Makris, Kerry-Anne Rye, Annemarie Hennessy
Preeclampsia is a hypertensive disorder of pregnancy. Abnormal placentation associated with poor placental invasion of the uterine vasculature by trophoblast cells, leading to poor placental perfusion, oxidative stress and inflammation, is implicated in its pathogenesis. A dyslipidemia characterised by low plasma levels of high density lipoproteins (HDL) and elevated triglycerides has been described in preeclampsia. Apolipoprotein A-I (apoA-I), a constituent of HDL is an anti-inflammatory agent. This study investigated whether apoA-I protects against hypertension and adverse placental changes in a pro-inflammatory cytokine (TNF-α) induced model of preeclampsia...
November 2, 2016: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/27806982/coupling-between-arterial-and-venous-cerebral-blood-flow-during-postural-change
#20
Shigehiko Ogoh, Takuro Washio, Hiroyuki Sasaki, Lonnie Grove Petersen, Niels H Secher, Kohei Sato
In supine humans the main drainage from the brain is through the internal jugular vein (IJV) but the vertebral veins (VV) become important during orthostatic stress because the IJV is partially collapsed. To identify the effect of this shift in venous drainage from the brain on the cerebral circulation, this study addressed both arterial and venous flow responses in the "anterior" and "posterior" parts of the brain when 9 healthy subjects (5 men) were seated and flow was manipulated by hyperventilation and inhalation of 6% carbon dioxide (CO2)...
November 2, 2016: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
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