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American Journal of Physiology. Heart and Circulatory Physiology

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https://www.readbyqxmd.com/read/28526710/gbt1118-a-potent-allosteric-modifier-of-hemoglobin-oxygen-affinity-increases-tolerance-to-severe-hypoxia-in-mice
#1
Kobina Dufu, Ozlem Yalcin, Eilleen Sy Ao-Ieong, Athiwat Hutchaleelala, Qing Xu, Zhe Li, Nicholas Vlahakis, Donna Oksenberg, Josh Lehrer-Graiwer, Pedro Cabrales
Adaptation to hypoxia requires compensatory mechanisms that affect oxygen (O2) transport and utilization. Decreased hemoglobin (Hb)-O2 affinity is considered part of the physiological adaptive process to chronic hypoxia. This manuscript explores the hypothesis that increased Hb-O2 affinity can complement acute physiological responses to hypoxia by increasing O2 uptake and delivery when compared to normal Hb-O2 affinity during acute severe hypoxia. To test this hypothesis, mice Hb-O2 affinity was increased via oral administration of 70 or 140 mg/kg GBT1118...
May 19, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28526709/acetylation-of-mitochondrial-proteins-by-gcn5l1-promotes-enhanced-fatty-acid-oxidation-in-the-heart
#2
Dharendra Thapa, Manling Zhang, Janet R Manning, Danielle Guimarães, Michael Stoner, Robert M O'Doherty, Sruti Shiva, Iain Scott
Lysine acetylation is a reversible post-translational modification, and is particularly important in the regulation of mitochondrial metabolic enzymes. Acetylation uses acetyl-CoA derived from fuel metabolism as a co-factor, thereby linking nutrition to metabolic activity. In this study, we investigated how mitochondrial acetylation status in the heart is controlled by food intake, and how these changes affect mitochondrial metabolism. We found that there was a significant increase in cardiac mitochondrial protein acetylation in mice fed a long-term high fat diet, and that this change correlated with an increase in the abundance of the mitochondrial acetyltransferase-related protein GCN5L1...
May 19, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28526708/vegf-b-friend-or-foe-to-the-heart-in-times-of-nutrient-excess
#3
Glenn C Rowe, Martin E Young
N/A.
May 19, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28526707/s-nitrosylation-of-vasp-at-cysteine-64-mediates-inflammation-stimulated-increase-in-microvascular-permeability
#4
Patricia Zamorano, Natalie Marin, Francisco Córdova, Alejandra Aguilar, Cynthia J Meininger, Mauricio P Boric, Nikola Golenhofen, Jorge Contreras, José Sarmiento, Walter N Duran, Fabiola A Sánchez
We tested the hypothesis that platelet-activating factor (PAF) induces S-nitrosylation of vasodilator-stimulated phosphoprotein (VASP) as a mechanism to reduce microvascular endothelial barrier integrity and stimulate hyperpermeability. PAF elevated S-nitrosylation of VASP above baseline levels in different endothelial cells and caused hyperpermeability. To ascertain the importance of eNOS subcellular location in this process, we used ECV-304 cells transfected with cytosolic eNOS (GFPeNOSG2A) and plasma membrane eNOS (GFPeNOSCAAX)...
May 19, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28526706/cardiac-hyporesponsiveness-in-severe-sepsis-is-associated-with-nitric-oxide-dependent-activation-of-g-protein-receptor-kinase
#5
Daniela Dal-Secco, Silvia DalBó, Natalia E S Lautherbach, Fábio N Gava, Mara Rubia Nunes Celes, Patricia Oliveira Benedet, Adriana H Souza, Juliana Akinaga, Vanessa Lima, Katiussia P Silva, Luiz Ricardo A Kiguti, Marcos A Rossi, Isis do Carmo Kettelhut, André Sampaio Pupo, Fernando Queiroz Cunha, Jamil Assreuy
G protein-coupled receptor kinase isoform 2 (GRK2) has a critical role in physiological and pharmacological responses to endogenous and exogenous substances. Sepsis causes an important cardiovascular dysfunction in which nitric oxide (NO) has a relevant role. The present study aimed to assess the putative effect of inducible NO synthase (NOS-2)-derived NO on the activity of GRK2 in the context of septic cardiac dysfunction. C57BL/6 mice were submitted to severe septic injury by cecal ligation and puncture (CLP)...
May 19, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28476925/detachable-glass-microelectrodes-for-recording-action-potentials-in-active-moving-organs
#6
Mladen Barbic, Angel Moreno, Timothy D Harris, Matthew W Kay
We describe new detachable floating glass micropipette electrode devices that provide targeted action potential recordings in active moving organs without requiring constant mechanical constraint or pharmacological inhibition of tissue motion. The technology is based on the concept of a glass micropipette electrode that is held firmly during cell targeting and intracellular insertion, after which a 100µg glass microelectrode, a "microdevice", is gently released to remain within the moving organ. The microdevices provide long-term recordings of action potentials, even during millimeter-scale movement of tissue in which the device is embedded...
May 5, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28476924/molecular-effects-of-exercise-training-in-patients-with-cardiovascular-disease-focus-on-skeletal-muscle-endothelium-and-myocardium
#7
Volker Adams, Bernhard Reich, Madlen Uhlemann, Josef Niebauer
For decades we know that exercise training exerts beneficial effects to the human body and clear evidence is available that a higher fitness level is associated with a lower incidence of suffering premature cardiovascular death. Despite this knowledge it took some time also to incorporate physical exercise training into the treatment plan for patients with cardiovascular disease (CVD). In recent years, in addition to continuous exercise training further training modalities like high intensity interval training (HIIT) and pyramid training have been introduced for CAD patients...
May 5, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28476923/acute-beetroot-juice-supplementation-on-sympathetic-nerve-activity-a-randomized-double-blind-placebo-controlled-proof-of-concept-study
#8
Karambir Notay, Anthony V Incognito, Philip J Millar
Acute dietary nitrate supplementation reduces resting blood pressure in healthy normotensives. This response is attributed to increased nitric oxide bioavailability and peripheral vasodilation, though nitric oxide also tonically inhibits central sympathetic outflow. We hypothesized that acute dietary nitrate (NO3(-)) supplementation using beetroot (BR) juice would reduce blood pressure and muscle sympathetic nerve activity (MSNA) at rest and during exercise. Fourteen participants (7 men, 25±10 years) underwent blood pressure and MSNA measurements before and after (165-180 minutes) ingestion of 70ml high-nitrate (~6...
May 5, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28476922/sarcolemmal-distribution-of-ica-and-incx-and-ca-autoregulation-in-mouse-ventricular-myocytes
#9
Hanne C Gadeberg, Cherrie H T Kong, Simon M Bryant, Andrew F James, Clive H Orchard
The balance of Ca influx and efflux regulates the Ca load of cardiac myocytes, a process known as autoregulation. Previous work has shown that Ca influx, via L-type Ca current (ICa), and efflux, via Na-Ca exchange (NCX), occur predominantly at t-tubules; however the role of t-tubules in autoregulation is unknown. We therefore investigated the sarcolemmal distribution of ICa and INCX, and autoregulation, in mouse ventricular myocytes using whole cell voltage-clamp and simultaneous Ca measurement in intact and detubulated (DT) cells...
May 5, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28476921/non-invasive-evaluation-of-left-ventricular-elastance-according-to-pressure-volume-curves-modeling-in-arterial-hypertension
#10
Benjamin Bonnet, Franck Jourdan, Guilhem du Cailar, Pierre Fesler
Background- End systolic left ventricular (LV) elastance (Ees) has been previously calculated and validated invasively using LV pressure-volume (PV) loops. Non invasive methods have been proposed, but clinical application remains complex. The aim of the present study was to 1) estimate Ees according to modeling of LV PV curve during ejection ("Ejection PV Curve" method) and validate our method with existing published LV PV loops data. 2) test clinical applicability to detect non invasively a difference in Ees between normotensive and hypertensive subjects...
May 5, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28476920/clinically-styled-vagus-nerve-stimulation-augments-spontaneous-discharge-in-second-and-higher-order-sensory-neurons-in-rat-nucleus-of-the-solitary-tract
#11
Eric Beaumont, Regenia B Phillips Campbell, Michael C Andresen, Stephanie Lc Scofield, Krishna Singh, Imad Libbus, Bruce H KenKnight, Logan Snyder, Nathan Cantrell
Vagus nerve stimulation (VNS) currently treats patients with drug resistant epilepsy, depression and heart failure. The mild intensities used in chronic VNS suggest that primary visceral afferents and central nervous system activation are involved. Here we measured the activity of neurons in the nucleus of the solitary tract (NTS) in anesthetized rats using clinically-styled VNS. Our chief findings indicate that VNS at threshold bradycardic intensity activated NTS neuron discharge in one third of NTS neurons...
May 5, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28476919/v%C3%AC-o2-kinetics-associated-with-moderate-intensity-exercise-in-heart-failure-impact-of-intrathecal-fentanyl-inhibition-of-group-iii-iv-locomotor-muscle-afferents
#12
Erik H Van Iterson, Bruce D Johnson, Michael J Joyner, Timothy B Curry, Thomas P Olson
Heart failure (HF) patients demonstrate impaired pulmonary, circulatory, and nervous system responses to exercise. While HF demonstrate prolonged (time-constant, τ) pulmonary oxygen uptake (V̇O2) on-kinetics contributing to exercise intolerance, it is unknown if abnormal V̇O2 kinetics couple with ventilatory and circulatory dysfunction secondary to impaired group III/IV afferents in HF. Because lower-lumbar intrathecal fentanyl inhibits locomotor muscle afferents resulting in improved exercise ventilation and hemodynamics, we tested the hypotheses, HF will demonstrate: 1) rapid V̇O2 on-kinetics, and 2) attenuated steady-state V̇O2 amplitude and oxygen deficit (O2def) during exercise with fentanyl versus placebo...
May 5, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28476918/endothelial-camp-deactivates-ischemia-reperfusion-induced-microvascular-hyperpermeability-via-rap1-mediated-mechanisms
#13
Adam H Korayem, Patricio E Mujica, Haruo Aramoto, Ricardo G Durán, Prerna R Nepali, David D Kim, Andrew L Harris, Fabiola A Sánchez, Walter N Duran
Approaches to reduce excessive edema due to the microvascular hyperpermeability that occurs during ischemia-reperfusion (I/R) are needed to prevent muscle compartment syndrome. We tested the hypothesis that cAMP-activated mechanisms actively restore barrier integrity in postischemic striated muscle. We found, using I/R in intact muscles and hypoxia-reoxygenation (H/R, an I/R mimic) in human microvascular endothelial cells (HMVEC), that hyperpermeability can be deactivated by increasing cAMP levels through application of forskolin...
May 5, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28455290/quantitative-cardiac-phosphoproteomics-profiling-during-ischemic-reperfusion-in-an-immature-swine-model
#14
Dolena R Ledee, MinA Kang, Masaki Kajimoto, Samuel Purvine, Heather Brewer, Ljiljana Pasa-Tolic, Michael A Portman
Ischemia/Reperfusion (I/R) results in altered metabolic and molecular responses; and phosphorylation is one of the most noted regulatory mechanisms mediating signaling mechanisms during physiological stresses. To expand our knowledge of the potential phosphoproteomic changes in the myocardium during I/R, we utilized iTRAQ-based analyses in left ventricular samples obtained from porcine hearts under control or I/R conditions. The data are available via ProteomeXchange with identifier PXD006066. We identified 1896 phosphopeptides within left ventricular control and I/R porcine samples...
April 28, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28455289/diminished-responsiveness-to-dobutamine-as-an-inotrope-in-mice-with-cecal-ligation-and-puncture-induced-sepsis-attribution-to-phosphodiesterase-4-upregulation
#15
Mari Sakai, Tokiko Suzuki, Kengo Tomita, Shigeyuki Yamashita, Sailesh Palikhe, Kohshi Hattori, Naoki Yoshimura, Naoyuki Matsuda, Yuichi Hattori
Dobutamine has been used in septic shock for many years as an only inotrope, but its benefit has been questioned. We weighed the effects of dobutamine and milrinone as inotropes in BALB/c mice with cecal ligation and puncture (CLP)-induced sepsis. CLP-induced septic mice exhibited significant cardiac inflammation, as indicated by greatly increased mRNAs of pro-inflammatory cytokines and robust infiltration of inflammatory cells in ventricular myocardium. Elevations of plasma cardiac troponin-I showed cardiac injury in CLP mice...
April 28, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28455288/cardiac-myofibrillar-contractile-properties-during-the-progression-from-hypertension-to-decompensated-heart-failure
#16
Laurin M Hanft, Craig A Emter, Kerry S McDonald
Heart failure arises, in part, from a constellation of changes in cardiac myocytes including remodeling, energetics, calcium handling, and myofibrillar function. However, little is known about the changes in myofibrillar contractile properties during the progression from hypertension to decompensated heart failure. The aim of this study was to provide a comprehensive assessment of myofibrillar functional properties from health to heart disease. A rodent model of uncontrolled hypertension was used to test the hypothesis that myocytes in compensated hearts exhibit increased force, higher rates of force development, faster loaded shortening, and greater power output; however, with progression to overt heart failure we predicted marked depression in these contractile properties...
April 28, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28455287/desmin-loss-and-mitochondrial-damage-precede-left-ventricular-systolic-failure-in-volume-overload-heart-failure
#17
Jason Guichard, Michael Paul Rogowski, Giulio Agnetti, Lianwu Fu, Pamela Powell, Chih-Chang Wei, James F Collawn, Louis J Dell'Italia
BACKGROUND: Heart failure due to chronic volume overload (VO) in the rat and human is characterized by disorganization of cardiomyocyte desmin/mitochondrial network. Here we test the hypothesis that desmin breakdown is an early and continuous process throughout VO. METHODS: Male Sprague-Dawley rats had aortocaval fistula (ACF) or sham surgery for 24 hours, 4 weeks or 12 weeks (wk). Desmin/mitochondrial ultrastructure was examined by transmission electron microscopy (TEM) and immunohistochemistry (IHC)...
April 28, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28455286/ultrasound-biomicroscopy-validation-of-a-murine-model-of-cardiac-hypertrophic-preconditioning-comparison-with-a-hemodynamic-assessment
#18
Jiayuan Huang, Jian Wu, Shijun Wang, Jieyun You, Yong Ye, Zhiwen Ding, Fenghua Yang, Xingxu Wang, Junjie Guo, Leilei Ma, Jie Yuan, Yunli Shen, Xiangdong Yang, Aijun Sun, Hong Jiang, Liping Bu, Peter H Backx, Junbo Ge, Yunzeng Zou
In mice, myocardial hypertrophic preconditioning (HP), which is produced by the removal of short-term transverse aortic constriction (TAC), was recently reported to render the heart resistant to hypertrophic responses induced by subsequent re-constriction (Re-TAC). However, there is no efficient non-invasive method for ensuring that the repeated aortic manipulations were successfully performed. We previously demonstrated that ultrasound biomicroscopy (UBM) is a non-invasive and effective approach for predicting TAC success...
April 28, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28432060/toll-like-receptor-2-tlr2-dominance-over-tlr4-in-stressful-conditions-for-its-detrimental-role-in-the-heart
#19
Ashim K Bagchi, Gauri Akolkar, Soma Mandal, Prathapan Ayyappan, Xi Yang, Pawan K Singal
It has been suggested that toll-like receptor 4 (TLR4) promotes interleukin-10 (IL-10)-mediated cardiac cell survival while another receptor, TLR2, from the same family is detrimental. Here we examined the interactive role of these two innate signaling molecules under stressful conditions including interleukin-10 knockout (IL-10(-/-)) mice, global ischemia/reperfusion (I/R) injury in rat hearts and in-vitro shRNA experimental models in presence or absence of IL-10 (10ng/ml). Circulating and myocardial levels of tumor necrosis factor-α (TNF-α) as well as apoptosis and fibrosis were higher in IL-10(-/-) mice...
April 21, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28432059/increased-amplitude-of-inward-rectifier-k-currents-with-advanced-age-in-smooth-muscle-cells-of-murine-superior-epigastric-arteries
#20
Sebastien Hayoz, Jessica Pettis, Vanessa Bradley, Steven S Segal, William F Jackson
Inward rectifier K(+) channels (KIR) may contribute to skeletal muscle blood flow regulation and adapt to advanced age. Using mouse abdominal wall superior epigastric arteries (SEAs) from either young (3-6 months) or old (24-26 months) male C57BL/6 mice, we investigated whether SEA smooth muscle cells (SMCs) express functional KIR, and how aging may affect KIR function. Freshly dissected SEAs were either enzymatically dissociated to isolate SMCs for electrophysiological recording (perforated patch) and mRNA expression, or used intact for pressure myography...
April 21, 2017: American Journal of Physiology. Heart and Circulatory Physiology
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