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American Journal of Physiology. Heart and Circulatory Physiology

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https://www.readbyqxmd.com/read/28733452/chronic-hypertension-increases-aortic-endothelial-hydraulic-conductivity-by-upregulating-endothelial-aquaporin-1-expres-sion
#1
Jimmy Deon Toussaint, Chirag Bharavi Raval, Tieuvi Nguyen, Hadi Fadaifard, Shripad Joshi, George Wolberg, Steven Quarfordt, Kung-Ming Jan, David S Rumschitzki
Numerous studies examine aquaporins' role in osmotic water transport in various systems but virtually none focus on aquaporins' role in hydrostatically-driven water transport involving mammalian cells save for our laboratory's recent study of aortic endothelial cells. Here we inves-tigate aquaporin-1 expression and function in the aortic endothelium in two high-renin rat mod-els of hypertension, the spontaneously hypertensive genetically altered Wystar-Kyoto rat variant and Sprague-Dawley rats made hypertensive by two kidney, one clip Goldblatt surgery...
July 21, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28733451/prolonged-sitting-leg-vasculopathy-contributing-factors-and-clinical-implications
#2
Jaume Padilla, Paul J Fadel
Atherosclerotic peripheral artery disease primarily manifests in the medium-to large-sized conduit arteries of the lower extremities. However, the factors underlying this increased vulnerability of leg macrovasculature to disease are largely unidentified. On the basis of recent studies, we propose that excessive time spent in the sitting position and the ensuing reduction in leg blood flow-induced shear stress causes endothelial cell dysfunction, a key predisposing factor to peripheral artery disease. In particular, this review summarizes the findings from laboratory-based sitting studies revealing acute leg vascular dysfunction with prolonged sitting in young healthy subjects, discusses the primary physiological mechanisms and the potential long-term implications of such leg vasculopathy with repeated exposure to prolonged sitting, as well as identifies strategies that may be effective at evading it...
July 21, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28733450/muscle-sympathetic-nerve-activity-and-volume-regulating-factors-in-healthy-pregnant-and-non-pregnant-women
#3
Nisha Charkoudian, Charlotte W Usselman, Rachel J Skow, Jeffery S Staab, Colleen Glyde Julian, Michael K Stickland, Radha S Chari, Rshmi Khurana, Sandra T Davidge, Margie H Davenport, Craig D Steinback
Healthy, normotensive human pregnancies are associated with striking increases in both plasma volume and vascular sympathetic nerve activity (SNA). In non-pregnant humans, volume regulatory factors including plasma osmolality, vasopressin and the renin-angiotensin-aldosterone system have important modulatory effects on control of sympathetic outflow. We hypothesized that pregnancy would be associated with changes in the relationships between SNA (measured as muscle SNA) and volume regulating factors, including plasma osmolality, plasma renin activity and arginine vasopressin (AVP)...
July 21, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28733449/mitochondrial-function-in-engineered-cardiac-tissues-is-co-regulated-by-extracellular-matrix-elasticity-and-tissue-alignment
#4
Davi Marco Lyra-Leite, Allen Mariano Andres, Andrew Patrick Petersen, Nethika Ruvini Ariyasinghe, Nathan Cho, Jezell Athena Lee, Roberta A Gottlieb, Megan L McCain
Mitochondria in cardiac myocytes are critical for generating ATP to meet the high metabolic demands associated with sarcomere shortening. Distinct remodeling of mitochondrial structure and function occur in cardiac myocytes in both developmental and pathological settings. However, the factors that underlie these changes are poorly understood. Because remodeling of tissue architecture and extracellular matrix (ECM) elasticity are also hallmarks of ventricular development and disease, we hypothesize that these environmental factors regulate mitochondrial function in cardiac myocytes...
July 21, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28733448/pathophysiology-of-cardiorenal-syndrome-in-patients-with-heart-failure-potential-therapeutic-targets
#5
Hiroyuki Takahama, Masafumi Kitakaze
Despite the development of pharmacological inventions and new non-pharamacological techniques to prevent and treat HF, the mortality rate in patients with symptomatic HF remains high. To conquer these difficulties, the pathophysiology of HF should be considered within a wide range of views. Given the diverse mechanisms of HF pathophysiology, renal and cardiac functions have close and complementary interconnections. Recent studies suggest that communication between kidney and heart through bidirectional pathways causes significant pathological changes...
July 21, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28733447/mineralocorticoid-receptor-antagonists-attenuate-exaggerated-exercise-pressor-reflex-responses-in-hypertensive-rats
#6
Ryan M Downey, Masaki Mizuno, Jere Holloway Mitchell, Wanpen Vongpatanasin, Scott A Smith
Exaggerated heart rate (HR) and blood pressure responses to exercise in hypertension are mediated, in part, by overactivity of the exercise pressor reflex (EPR). The mechanisms underlying this EPR dysfunction have not been fully elucidated. Previous studies have shown that stimulation of mineralocorticoid receptors (MR) with exogenous administration of aldosterone in normal, healthy rats reproduces the EPR overactivity characteristic of hypertensive animals. Conversely, the purpose of this study was to examine whether antagonizing MR with spironolactone (SPIR) or eplerenone (EPL) in decerebrated hypertensive rats ameliorates abnormal EPR function...
July 21, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28733446/how-does-pressure-overload-cause-cardiac-hypertrophy-and-dysfunction-high-ouabain-affinity-cardiac-na-pumps-are-crucial
#7
Mordecai P Blaustein
Left ventricular hypertrophy is frequently observed in hypertensive patients, and is believed to be due to the pressure overload and cardiomyocyte stretch. Three recent reports on mice with genetically-engineered Na(+) pumps, however, demonstrate that cardiac ouabain-sensitive α2 Na(+) pumps play a key role in the pathogenesis of trans-aortic constriction (TAC)-induced hypertrophy. Hypertrophy was delayed/attenuated in mice with mutant, ouabain-resistant α2 Na(+) pumps and in mice with cardiac-selective knockout (KO) or transgenic overexpression (TG) of α2 Na(+) pumps...
July 21, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28733445/enhanced-no-dependent-pulmonary-vasodilation-limits-increased-vasoconstrictor-sensitivity-in-neonatal-chronic-hypoxia
#8
Joshua R Sheak, Laura Weise-Cross, Ray J deKay, Benjimen R Walker, Nikki L Jernigan, Thomas C Resta
Augmented vasoconstrictor reactivity is thought to play an important role in the development of chronic hypoxia (CH)-induced neonatal pulmonary hypertension (pHTN). However, whether this response to CH results from pulmonary endothelial dysfunction and reduced NO-mediated vasodilation is not well understood. We hypothesized that neonatal CH enhances basal tone and pulmonary vasoconstrictor sensitivity by limiting NO-dependent pulmonary vasodilation. To test this hypothesis, we assessed effects of the NO synthase (NOS) inhibitor N(w)-nitro-L-arginine (L-NNA) on baseline pulmonary vascular resistance (PVR) and vasoconstrictor sensitivity to the thromboxane mimetic U-46619 in saline-perfused lungs (in situ) from 2-wk-old control and CH (12 day exposure, 0...
July 21, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28710072/circulating-acylcarnitine-profile-in-human-heart-failure-a-surrogate-of-fatty-acid-metabolic-dysregulation-in-mitochondria-and-beyond
#9
Matthieu Ruiz, Francois Labarthe, Annik Fortier, Bertrand Bouchard, Julie Thompson Legault, Virginie Bolduc, Odile Rigal, Jane Chen, Anique Ducharme, Peter A Crawford, Jean-Claude Tardif, Christine Des Rosiers
Heart failure (HF) is associated with metabolic perturbations, particularly of fatty acids (FA), which remain to be better understood in humans. This study aimed at testing the hypothesis that HF patients with reduced ejection fraction, display systemic perturbations in levels of energy-related metabolites, especially those reflecting dysregulation of FA metabolism, namely acylcarnitines (ACs). Circulating metabolites were assessed using mass spectrometry (MS)-based methods in two cohorts. The main cohort consisted of 72 controls and 68 HF patients, exhibiting depressed left ventricular ejection fraction (25...
July 14, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28710071/editorial-focus-on-ms-h-00207-2017r2-uncovering-novel-roles-for-matrix-metalloproteinases-in-preeclampsia
#10
Christopher A Foote, Luis A Martinez-Lemus
Matrix metalloproteinases role in preeclampsia.
July 14, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28710070/tnf-%C3%AE-receptor-1-knockdown-in-subfornical-organ-ameliorates-sympathetic-excitation-and-cardiac-hemodynamics-in-heart-failure-rats
#11
Yang Yu, Shun-Guang Wei, Robert M Weiss, Robert B Felder
In systolic heart failure (HF), circulating proinflammatory cytokines upregulate inflammation and renin-angiotensin system (RAS) activity in cardiovascular regions of the brain, contributing to sympathetic excitation and cardiac dysfunction. Important among these is the subfornical organ (SFO), a forebrain circumventricular organ that lacks an effective blood-brain barrier and senses circulating humors. We hypothesized that the tumor necrosis factor-α (TNF-α) receptor 1 (TNFR1) in the SFO contributes to sympathetic excitation and cardiac dysfunction in HF rats...
July 14, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28710069/vitamin-c-mitigates-oxidative-nitrosative-stress-and-inflammation-in-doxorubicin-induced-cardiomyopathy
#12
Gauri Akolkar, Danielle da Silva Dias, Prathapan Ayyappan, Ashim K Bagchi, Davinder S Jassal, Vera Mc Salemi, Maria Claudia Irigoyen, Katia De Angelis, Pawan K Singal
Increase in oxidative/nitrosative stress is one of the mechanisms associated with the development of cardiotoxicity due to Doxorubicin (Dox), a potent chemotherapy drug. Previously, we reported mitigation of Dox-induced oxidative/nitrosative stress and apoptosis by Vitamin C (Vit C) in isolated cardiomyocytes. In the present in vivo study in rats, we investigated the effect of prophylactic treatment with Vit C on Dox-induced apoptosis, inflammation, oxidative/nitrosative stress, cardiac dysfunction and Vit C transporter proteins...
July 14, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28710068/gq-activated-fibroblasts-induce-cardiomyocyte-action-potential-prolongation-and-automaticity-in-a-3d-microtissue-environment
#13
Celinda M Kofron, Tae Yun Kim, Michelle E King, An Xie, Feng Feng, Elizabeth Park, Zhilin Qu, Bum-Rak Choi, Ulrike Mende
Cardiac fibroblasts (CFs) are known to regulate cardiomyocyte (CM) function in vivo and in 2D in vitro cultures. This study examined the effect of CF activation on the regulation of CM electrical activity in a 3D microtissue environment. Using a scaffold-free 3D platform with interspersed neonatal rat ventricular CMs and CFs, Gq-mediated signaling was selectively enhanced in CFs by Gαq adenoviral infection prior to co-seeding with CMs in non-adhesive hydrogels. After 3 days, the microtissues were analyzed by signaling assay, histological staining, quantitative PCR, Western blots, optical mapping with voltage- or calcium-sensitive dyes, and microelectrode recordings of CF resting membrane potential (RMPCF)...
July 14, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28710067/a-comparison-of-passive-hind-limb-cycling-and-active-upper-limb-exercise-provides-new-insights-into-systolic-dysfunction-following-spinal-cord-injury
#14
Kathryn M DeVeau, Kathryn A Harman, Jordan W Squair, Andrei V Krassioukov, David Magnuson, Christopher R West
BACKGROUND: Active upper-limb and passive lower-limb exercise are two interventions used in the spinal cord injury (SCI) population. While the global cardiac responses have been previously studied, it is unclear how either exercise influences contractile cardiac function. Here, the cardiac contractile and volumetric responses to upper-limb (swim) and passive lower-limb exercise are investigated in rodents with a severe high-thoracic SCI. METHODS: Animals were divided into a control (CON), SCI no exercise (NO-EX), SCI passive hind-limb cycling (PHLC) or SCI swim (SWIM) group...
July 14, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28687588/the-carotid-baroreflex-modifies-the-pressor-threshold-of-the-muscle-metaboreflex-in-humans
#15
Masashi Ichinose, Tomoko K Ichinose-Kuwahara, Kazuhito Watanabe, Narihiko Kondo, Takeshi Nishiyasu
The purpose of present study was to test our hypothesis that unloading the carotid baroreceptors alters the threshold and gain of the muscle metaboreflex in humans. Ten healthy subjects performed a static handgrip exercise at 50% of maximum voluntary contraction. Contraction was sustained for 15, 30, 45 and 60 s, and was followed by 3 min of forearm circulatory arrest, during which forearm muscular pH is known to decrease linearly with increasing contraction time. The carotid baroreceptors were unloaded by applying 0...
July 7, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28687587/foxo1-regulates-myocardial-glucose-oxidation-rates-via-transcriptional-control-of-pyruvate-dehydrogenase-kinase-4-expression
#16
Keshav Gopal, Bruno Saleme, Rami Al Batran, Hanin Aburasayn, Amina Eshreif, Kim L Ho, Wayne K Ma, Malak Almutairi, Farah Eaton, Manoj Gandhi, Edwards A Park, Gopinath Sutendra, John R Ussher
Pyruvate dehydrogenase (PDH) is the rate-limiting enzyme for glucose oxidation and a critical regulator of metabolic flexibility during the fasting to feeding transition. PDH is regulated via both PDH kinases (PDHK), and PDH phosphatases, which phosphorylate/inactivate and dephosphorylate/activate PDH, respectively. Our goal was to determine whether the transcription factor, forkhead box O1 (FoxO1) regulates PDH activity and glucose oxidation in the heart via increasing expression of Pdk4, the gene encoding PDHK4...
July 7, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28667055/increased-activity-of-the-orexin-system-in-the-paraventricular-nucleus-contributes-to-salt-sensitive-hypertension
#17
Michael J Huber, Yuanyuan Fan, Enshe Jiang, Fengli Zhu, Robert A Larson, Jianqun Yan, Ningjun Li, Qing-Hui Chen, Zhiying Shan
The orexin system is involved in vasopressin (AVP) regulation and its over activation has been implicated in hypertension. However, its role in salt-sensitive hypertension (SSHTN) is unknown. Here we test the hypothesis that hyperactivity of the orexin system in the paraventricular nucleus (PVN) contributes to SSHTN via enhancing AVP signaling. Eight-week-old male Dahl salt sensitive (Dahl S) and age and sex matched Sprague Dawley (SD) rats were placed on a high salt (HS, 8% NaCl) or normal salt (NS, 0.4% NaCl) diet for 4 weeks...
June 30, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28667054/analysis-of-decreases-in-systemic-arterial-pressure-and-heart-rate-in-response-to-the-hydrogen-sulfide-donor-sodium-sulfide
#18
Kevin W Swan, Bryant Minkyu Song, Allen L Chen, Travis J Chen, Ryan A Chan, Bradley T Guidry, Prasad V G Katakam, Edmund K Kerut, Thomas D Giles, Philip Kadowitz
The actions of hydrogen sulfide (H2S) on the heart and vasculature have been extensively reported. However, the mechanisms underlying the effects of H2S are unclear in the anesthetized rat. The objective of the current study is to investigate the effect of H2S on the electrocardiogram and examine the relationship between H2S-induced changes in heart rate (HR), mean arterial pressure (MAP), and respiratory function. Intravenous (iv) administration of the H2S donor sodium sulfide (Na2S) in the anesthetized Sprague-Dawley (SD) rat decreased MAP and HR and produced changes in respiratory function...
June 30, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28667053/microrna-124-control-human-vascular-smooth-muscle-cell-phenotypic-switch-via-sp1
#19
Yangfeng Tang, Shangyi Yu, Yang Liu, Jiajun Zhang, Lin Han, Zhiyun Xu
Phenotypic switch of vascular smooth muscle cells (VSMCs) plays an important role in the pathogenesis of atherosclerosis and aortic dissection. However, the mechanisms of phenotypic modulation are still unclear. MicroRNAs have emerged as important regulators of VSMC function. We recently found that MicroRNA-124(miR-124) was down-regulated in proliferative vascular diseases. The purpose of this study was to investigate the critical role played by the aberrant expression of miR-124 in human aortic VSMC phenotypic switch and to unravel the signal transduction pathways...
June 30, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28667052/hearts-lacking-plasma-membrane-katp-channels-display-changes-in-basal-aerobic-metabolic-substrate-preference-and-ampk-activity
#20
Nermeen Youssef, Scott Campbell, Amy Barr, Manoj Gandhi, Beth Hunter, Vernon Dolinksy, Jason R B Dyck, Alexander S Clanachan, Peter E Light
Cardiac ATP-sensitive potassium (KATP) channels couple changes in cellular metabolism to membrane excitability and are activated during metabolic stress. Although under basal aerobic conditions, KATP channels are thought to be predominately closed. Despite intense research into the roles of KATP channels during metabolic stress, their contribution to aerobic basal cardiac metabolism has not been investigated previously. METHODS: Hearts from Kir6.2+/+ and Kir6.2 -/- mice were perfused in working mode and rates of glycolysis, fatty acid oxidation and glucose oxidation were measured...
June 30, 2017: American Journal of Physiology. Heart and Circulatory Physiology
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