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American Journal of Physiology. Heart and Circulatory Physiology

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https://www.readbyqxmd.com/read/30028204/oxidation-of-ryanodine-receptor-following-ischemia-reperfusion-increases-propensity-of-ca-2-waves-during-%C3%AE-adrenergic-receptor-stimulation
#1
Elisa Bovo, Stefan R Mazurek, Aleksey V Zima
β-Adrenergic receptor (β-AR) activation produces the main positive inotropic response of the heart. During ischemia/reperfusion (I/R), however, β-AR activation can trigger life-threatening arrhythmias. Since I/R is frequently associated with oxidative stress, we investigated whether ryanodine receptor (RyR) oxidation contributes to proarrythmogenic Ca2+ waves during β-AR activation. Measurements of contractile and electrical activity from Langendorff-perfused rabbit hearts revealed that I/R produces tachyarrhythmias...
July 20, 2018: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/30028203/caveolin-3-ko-disrupts-t-tubule-structure-and-decreases-t-tubular-i-ca-density-in-mouse-ventricular-myocytes
#2
Simon M Bryant, Cherrie H T Kong, Judy J Watson, Hanne C Gadeberg, David M Roth, Hemal H Patel, Mark B Cannell, Andrew F James, Clive H Orchard
Caveolin-3 (Cav-3) is a protein that has been implicated in t-tubule formation and function in cardiac ventricular myocytes. In cardiac hypertrophy and failure, Cav-3 expression decreases, t-tubule structure is disrupted and excitation-contraction coupling (ECC) is impaired. However, the extent to which the decrease in Cav-3 expression underlies these changes is unclear. We therefore investigated the structure and function of myocytes isolated from the hearts of Cav-3 KO mice. These mice showed cardiac dilatation and decreased ejection fraction in vivo, compared to WT controls...
July 20, 2018: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/30028202/normal-patterns-of-thoracic-aortic-wall-shear-stress-measured-using-4d-flow-mri-in-a-large-population
#3
Fraser Maurice Callaghan, Stuart Michael Grieve
Wall shear stress (WSS) plays a governing role in vascular remodelling and a pathogenic role in vessel wall diseases. Little however, is known of the normal WSS patterns in the aorta as there is currently no practical means to routinely measure WSS, and no normal ranges derived from population data exist. WSS measurements were made on the aorta of 224 subjects with normal anatomy using 4-dimensional flow MRI (4D-flow) with multiple encoding velocities and an optimized post-processing routine. The spatial and temporal variation in WSS and oscillatory shear index was analyzed using a flat map representation of the unfolded aorta...
July 20, 2018: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/30028201/surgical-reinforcement-alters-collagen-alignment-and-turnover-in-healing-myocardial-infarcts
#4
Laura Rose Caggiano, Jia-Jye Lee, Jeffrey W Holmes
Previous studies suggest that the composition and global mechanical properties of the scar tissue that forms following a myocardial infarction are key determinants of long-term survival, and emerging therapies such as biomaterial injection are designed in part to alter those mechanical properties. However, recent evidence suggests that local mechanics regulate scar formation post-MI, so that perturbing infarct mechanics could have unexpected consequences. We therefore tested the effect of changes in local mechanical environment on scar collagen turnover, accumulation, and alignment in 60 Sprague-Dawley rats at 1, 2, 3 and 6 weeks post-MI by sewing a Dacron patch to the epicardium to eliminate circumferential strain while permitting continued longitudinal stretching with each heartbeat...
July 20, 2018: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/30028200/statistical-considerations-in-reporting-cardiovascular-research
#5
Merry L Lindsey, Gillian A Gray, Susan K Wood, Douglas Curran-Everett
The problem of inadequate statistical reporting is long-standing and widespread in the biomedical literature, including in cardiovascular physiology. Although guidelines for reporting statistics have been available in clinical medicine for some time, there are currently no guidelines specific to cardiovascular physiology. To assess the need for guidelines, we determined the type and frequency of statistical tests and procedures currently used in American Journal of Physiology: Heart and Circulatory Physiology...
July 20, 2018: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/30028199/new-insights-into-arterial-stiffening-does-sex-matter
#6
Benard O Ogola, Margaret A Zimmerman, Gabrielle L Clark, Caleb M Abshire, Kaylee M Gentry, Kristin S Miller, Sarah H Lindsey
This review will discuss sexual dimorphism in arterial stiffening, interactions with disease pathology, and the influence of sex on mechanisms and pathways. Arterial stiffness predicts cardiovascular mortality independent of blood pressure. In fact, patients with increased arterial stiffness have a 48% higher risk for developing cardiovascular disease. Like other cardiovascular pathologies, arterial stiffness is sexually dimorphic. Young women have lower stiffness compared with aged-matched men, but this sex difference reverses during normal aging...
July 20, 2018: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/30028198/astrocyte-produced-carbon-monoxide-co-and-the-co-donor-corm-a1-protect-against-cerebrovascular-dysfunction-caused-by-prolonged-neonatal-asphyxia
#7
Helena Parfenova, Massroor Pourcyrous, Alexander L Fedinec, Jianxiong Liu, Shymali Basuroy, Charles W Leffler
Neonatal asphyxia leads to cerebrovascular disease and neurological complications via a mechanism that may involve oxidative stress. Carbon monoxide (CO) is an antioxidant messenger produced via a heme oxygenase (HO)-catalyzed reaction. Cortical astrocytes are the major cells in the brain that express constitutive HO-2 isoform. We tested the hypothesis that CO, produced by astrocytes, has cerebroprotective properties during neonatal asphyxia. We developed a survival model of prolonged asphyxia in newborn pigs that combines insults of severe hypoxia, hypercapnia, and acidosis while avoiding extreme hypotension and cerebral blood flow reduction...
July 20, 2018: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/30028197/acute-isoproterenol-leads-to-age-dependent-arrhythmogenesis-in-guinea-pigs
#8
Kathleen Camille Woulfe, Cortney E Wilson, Shane Nau, Sarah Chau, Elisabeth K Phillips, Shulun Zang, Christine Tompkins, Carmen C Sucharov, Shelley D Miyamoto, Brian L Stauffer
Sudden cardiac death from ventricular arrhythmias is more common in adults with heart failure compared to pediatric heart failure patients. We identified age-specific differences in arrhythmogenesis using a guinea pig model of acute β-adrenergic stimulation. Young and adult guinea pigs were exposed to a β-adrenergic agonist, isoproterenol (ISO, 0.7mg/kg), for 30 minutes in the absence or presence of flecainide (20mg/kg), an antiarrhythmic that blocks sodium and ryanodine channels. Implanted cardiac monitors (Reveal LINQ{trade mark, serif}, Medtronic) were used to monitor heart rhythm...
July 20, 2018: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/30028196/fgf23-impairs-peripheral-microvascular-function-in-renal-failure
#9
Melissa Verkaik, Rio P Juni, Ellen P M van Loon, Erik van Poelgeest, Rick F J Kwekkeboom, Zeineb Gam, William G Richards, Pieter M Ter Wee, Joost G J Hoenderop, Etto C Eringa, Marc G Vervloet
BACKGROUND: Cardiovascular diseases account for approximately 50% of mortality in patients with chronic kidney disease (CKD). Fibroblast growth factor 23 (FGF23) is independently associated with endothelial dysfunction and cardiovascular mortality. We hypothesized that CKD impairs microvascular endothelial function and that this can be attributed to FGF23. METHODS: Mice were subjected to partial nephrectomy (5/6Nx) or sham-surgery. To evaluate the functional role of FGF23, non-CKD mice received FGF23 injections, and CKD mice received FGF23 blocking antibodies following 5/6Nx surgery...
July 20, 2018: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/30004811/non-invasive-wave-intensity-analysis-predicts-functional-worsening-in-children-with-pulmonary-arterial-hypertension
#10
Michal Schafer, Neil Wilson, D Dunbar Ivy, Richard Ing, Steven H Abman, Lorna Browne, Gareth Morgan, Michael Ross, Daniel McLennan, Alex Barker, Brian Fonseca, Michael Di Maria, Kendall S Hunter, Uyen Truong
The purpose of this study was to characterize the pulmonary vascular stiffness using wave intensity analysis (WIA) in children with pulmonary arterial hypertension (PAH), compare the WIA indices with catheterization and MRI derived hemodynamics, and assess the prognostic ability of WIA derived biomarkers to predict the functional worsening. WIA was performed in children with PAH (n=40) and healthy controls (n=15) from phase-contrast MRI derived flow and area waveforms in the main pulmonary artery. From comprehensive WIA spectra, we collected and compared with healthy controls forward compression waves (FCW), backward compression waves (BCW), forward decompression waves (FDW), and wave propagation speed (c-MPA)...
July 13, 2018: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/30004810/role-of-the-heart-in-blood-pressure-lowering-during-chronic-baroreflex-activation-insight-from-an-in-silico-analysis
#11
John S Clemmer, William Andrew Pruett, Robert L Hester, Radu Iliescu, Thomas E Lohmeier
Electrical stimulation of the baroreflex chronically suppresses sympathetic activity and arterial pressure and is currently being evaluated for the treatment of resistant hypertension. The antihypertensive effects of baroreflex activation are often attributed to renal sympathoinhibition. However, baroreflex activation also decreases heart rate, and robust blood pressure lowering occurs even after renal denervation. Because controlling renal sympathetic nerve activity and cardiac autonomic activity cannot be achieved experimentally, we used an established mathematical model of human physiology (HumMod) to provide mechanistic insight into their relative and combined contributions to the cardiovascular responses during baroreflex activation...
July 13, 2018: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/30004809/hypothermia-elongates-the-contraction-relaxation-cycle-in-explanted-human-failing-heart-decreasing-the-time-for-ventricular-filling-during-diastole
#12
Halvard Gautefall Hiis, Marie Victoire Cosson, Christen P Dahl, Arnt E Fiane, Finn Olav Levy, Geir Øystein Andersen, Kurt Allen Krobert
Targeted temperature management (TTM) is part of the standardized treatment for cardiac arrest patients. Hypothermia decreases cerebral oxygen consumption and induces bradycardia, thus, increasing the heart rate may be considered to maintain cardiac output. We hypothesized that increasing heart rate during hypothermia would impair diastolic function. Human left ventricular trabeculae obtained from explanted hearts of patients with terminal heart failure were stimulated at 0.5 Hz and contraction-relaxation cycles recorded...
July 13, 2018: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/30004258/characterization-of-a-mouse-model-of-obesity-related-fibrotic-cardiomyopathy-that-recapitulates-features-of-human-heart-failure-with-preserved-ejection-fraction
#13
Linda Alex, Ilaria Russo, Volodymir Holoborodko, Nikolaos G Frangogiannis
Heart Failure with preserved Ejection Fraction (HFpEF) is caused, or exacerbated by a wide range of extracardiac conditions. Diabetes, obesity and metabolic dysfunction are associated with a unique HFpEF phenotype, characterized by inflammation, cardiac fibrosis and microvascular dysfunction. Development of new therapies for HFpEF is hampered by the absence of reliable animal models. The leptin resistant db/db mouse has been extensively studied as a model of diabetes-associated cardiomyopathy; however data on the functional and morphological alterations in db/db hearts are conflicting...
July 13, 2018: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/30004252/chronic-treatment-with-the-mitochondrial-peptide-humanin-prevents-age-related-myocardial-fibrosis-in-mice
#14
Qing Qin, Hemal Mehta, Kelvin Yen, Gerardo Navarrete, Sebastian Brandhorst, Junxiang Wan, Silvia Delrio, Lilach O Lerman, Pinchas Cohen, Amir Lerman
AIMS: Cardiac fibrosis is a biological process that increases with age and contributes to myocardial dysfunction. Humanin (HN) is an endogenous mitochondrial derived peptide (MDP) which has cytoprotective effects and reduces oxidative stress. The current study aimed to test the hypothesis that chronic supplementation of exogenous HN in middle-aged mice could prevent and reverse cardiac fibrosis and apoptosis in the aging heart. METHODS AND RESULTS: Female C57BL/6N mice 18 months of age received 14-month intraperitoneal injections of vehicle (Old, n=6), or HN analog HNG (4mg/kg twice per week)(Old+HNG, n=8) were sacrificed at 32 months of age...
July 13, 2018: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/30004243/mitochondria-the-target-of-myocardial-conditioning
#15
Kerstin Boengler, Günter Lochnit, Rainer Schulz
Several interventions such as ischemic preconditioning, remote pre-/perconditioning, or postconditioning are known to decrease lethal myocardial ischemia/reperfusion injury. Whereas several signal transduction pathways become activated by such maneuvers, they all have a common endpoint, namely the mitochondria. The organelles represent an essential target of the cardioprotective strategies and the preservation of mitochondrial function is central for the reduction of ischemia/reperfusion injury. In the present review we address the role of mitochondria in the different conditioning strategies; in particular, we will focus on alterations of mitochondrial function in terms of energy production, formation of reactive oxygen species, opening of the mitochondrial permeability transition pore, and mitochondrial dynamics induced by ischemia/reperfusion...
July 13, 2018: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/30004239/proteomics-reveals-rictor-as-a-non-canonical-tgfb-signaling-target-during-aneurysm-progression-in-marfan-mice
#16
Sarah J Parker, Aleksandr Stotland, Elena MacFarlane, Nicole Wilson, Amanda Orosco, Vidya Venkatraman, Kyle Madrid, Roberta A Gottlieb, Harry C Dietz, Jennifer E Van Eyk
OBJECTIVE: To (1) analyze the ascending aortic proteome within a mouse model of MFS (Fbn1C1041G/+ ) at early and late stages of aneurysm and subsequently to (2) test a novel hypothesis formulated based on this unbiased proteomic screen that links changes in integrin composition to TGFβ-dependent activation of the Rapamycin-Independent Component of TOR (Rictor) signaling pathway. Approach & Results. Ingenuity pathway analysis of over 1000 proteins quantified from in vivo MFS mouse aorta by data independent acquisition mass-spectrometry revealed a predicted upstream regulator, Rictor, that was selectively activated in aged MFS mice...
July 13, 2018: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/30004238/not-all-fiber-is-good-for-you-targeting-fibroblast-activation-to-improve-cardiac-function-in-heart-failure
#17
Kristofer J Haushalter, Hemal H Patel
No abstract text is available yet for this article.
July 13, 2018: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/30004237/proteomic-analysis-of-aortic-smooth-muscle-cell-secretions-reveals-an-association-of-myosin-heavy-chain-11-with-abdominal-aortic-aneurysm
#18
Utako Yokoyama, Noriaki Arakawa, Ryo Ishiwata, Shota Yasuda, Tomoyuki Minami, Motohiko Goda, Keiji Uchida, Shinichi Suzuki, Masataka Matsumoto, Nobusato Koizumi, Masataka Taguri, Hisashi Hirano, Koichi Yoshimura, Hitoshi Ogino, Munetaka Masuda, Yoshihiro Ishikawa
Abdominal aortic aneurysm (AAA) is a life-threatening disease, and no disease-specific circulating biomarkers for AAA screening are currently available. We have identified a smooth muscle cell (SMC)-specific biomarker for AAA. We cultured aneurysmal tunica media that were collected from eight patients undergoing elective open-repair surgeries. Secreted proteins into culture medium were subjected to liquid chromatography/tandem mass spectrometry. Myosin heavy chain 11 (myosin-11) was identified as a SMC-specific protein in the tunica media-derived secretions of all patients...
July 13, 2018: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/30004235/the-piezo1-cation-channel-mediates-uterine-artery-shear-stress-mechanotransduction-and-vasodilation-during-rat-pregnancy
#19
Liam John, Nga Ling Ko, Alexander Gokin, Natalia Gokina, Maurizio Mandala, George Osol
During mammalian pregnancy, the uterine circulation must undergo substantial vasodilation and growth to maintain sufficient uteroplacental perfusion. Although nitric oxide (NO) has been shown to be a key mediator of these processes, the mechanisms that augment uterine artery NO signaling during gestation have not been identified. We hypothesized that Piezo1, a recently-discovered cation channel, may be involved in the process of shear stress mechanotransduction, as other studies have shown that it is both mechanosensitive and linked to NO production...
July 13, 2018: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/30004234/regional-and-temporal-changes-in-left-ventricular-strain-and-stiffness-in-a-porcine-model-of-myocardial-infarction
#20
William M Torres, Julia Jacobs, Heather Doviak, Shayne C Barlow, Michael R Zile, Tarek Shazly, Francis G Spinale
The aim of this study was to quantify regional changes in myocardial biomechanics in a large animal model of MI. Post-MI remodeling has distinct regional effects throughout the LV myocardium. Regional quantification of LV biomechanical behavior could help explain changes in global function and thus advance clinical assessment of post-MI remodeling. The present study is based on a porcine MI model to characterize LV biomechanics over 28 days post-MI via speckle-tracking echocardiography (STE). Regional myocardial strain and strain rate were recorded in the circumferential, radial, and longitudinal directions at baseline and at three, 14, and 28 days post-MI...
July 13, 2018: American Journal of Physiology. Heart and Circulatory Physiology
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