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    9817 results match your criteria American Journal of Physiology - Heart and Circulatory Physiology[Journal]

    1 OF 197

    Lower Resting and Exercise-Induced Circulating Angiogenic Progenitors and Angiogenic T-Cells in Older Men.
    Am J Physiol Heart Circ Physiol 2017 Nov 22:ajpheart.00592.2017. Epub 2017 Nov 22.
    Edinburgh Napier University.
    Ageing is associated with a dysfunctional endothelial phenotype, as well as reduced angiogenic capabilities. Exercise exerts beneficial effects on the cardiovascular system, possibly by increasing/maintaining the number and/or function of circulating angiogenic cells (CACs) that are known to decline with age. However, the relationship between cardiorespiratory fitness (CRF) and age related changes in frequency of CACs, as well as the exercise-induced responsiveness of CACs in older individuals has not yet been determined. Read More

    Burst Patterning of Hypothalamic Paraventricular Nucleus-Driven Sympathetic Nerve Activity in Angiotensin II-Salt Hypertension.
    Am J Physiol Heart Circ Physiol 2017 Nov 22:ajpheart.00560.2017. Epub 2017 Nov 22.
    University of Texas Health Sciences Center at San Antonio
    Angiotensin II-salt hypertension (AngII-salt HTN) selectively increases splanchnic sympathetic nerve activity (sSNA), but the extent to which this reflects increased respiratory versus cardiac rhythmic bursting is unknown. Here, integrated sSNA was elevated in AngII infused rats fed a high salt (2% NaCl) diet (AngII-HSD) compared to vehicle infused rats fed a normal salt (0.4% NaCl) diet (Veh-NSD) (P<0. Read More

    Flow-mediated dilation stimulated by sustained increases in shear stress: A useful tool for assessing endothelial function in humans?
    Am J Physiol Heart Circ Physiol 2017 Nov 22:ajpheart.00534.2017. Epub 2017 Nov 22.
    Queen's University
    Investigations of human conduit artery endothelial function via flow-mediated vasodilation (FMD) have largely been restricted to the reactive hyperemia (RH) technique, wherein a transient increase in shear stress following the release of limb occlusion stimulates upstream conduit artery vasodilation (RH-FMD). FMD can also be assessed in response to sustained increases in shear stress (sustained stimulus (SS)-FMD), most often created with limb heating or exercise. Exercise in particular creates a physiologically-relevant stimulus because shear stress increases, and FMD occurs, during typical day-to-day activity. Read More

    Acute lysyl oxidase inhibition alters microvascular function in normotensive, but not hypertensive, men and women.
    Am J Physiol Heart Circ Physiol 2017 Nov 22:ajpheart.00521.2017. Epub 2017 Nov 22.
    The Pennsylvania State University
    The Lysyl oxidase (LOX) family of enzymes regulates collagen cross-linking. LOX is upregulated in hypertension, increasing vascular stiffness. In vivo human research is sparse as long-term LOX inhibition in animals causes vascular instability. Read More

    Revisiting the Physiological Effects of Exercise Training on Autonomic Regulation and Chemoreflex Control in Heart Failure: Does Ejection Fraction Matter?
    Am J Physiol Heart Circ Physiol 2017 Nov 22:ajpheart.00407.2017. Epub 2017 Nov 22.
    Pontificia Universidad Católica de Chile
    Heart failure (HF) is a global public health problem that, independent of its etiology (reduced (HFrEF) or preserved ejection fraction (HFpEF)), is characterized by functional impairments of cardiac function, chemoreflex hypersensitivity, baroreflex sensitivity (BRS) impairment, and abnormal autonomic regulation, all of which contribute to increased morbidity and mortality. Exercise training (ExT) has been identified as a nonpharmacological therapy capable of restoring normal autonomic function and improving survival in patients with HFrEF. Improvements in autonomic function after ExT are correlated with restoration of normal peripheral chemoreflex sensitivity and BRS in HFrEF. Read More

    Exercise Facilitates Early Recognition of Cardiac and Vascular Remodeling in Chronic Thrombo-Embolic Pulmonary Hypertension in a Novel CTEPH Swine Model.
    Am J Physiol Heart Circ Physiol 2017 Nov 22:ajpheart.00380.2017. Epub 2017 Nov 22.
    Erasmus MC
    Chronic thrombo-embolic pulmonary hypertension (CTEPH) develops in 4% of patients after pulmonary embolism and is accompanied by an impaired exercise tolerance, which is ascribed to the increased right ventricular (RV) afterload and a ventilation/perfusion (V/Q) mismatch in the lungs. This study investigated changes in arterial PO2 and hemodynamics in response to graded treadmill exercise during development and progression of CTEPH in a swine model. Swine were chronically instrumented and received multiple pulmonary embolisms by (i) microsphere infusion (Spheres) over five weeks, (ii) endothelial dysfunction by administration of eNOS inhibitor L-N(ω)-Nitroarginine methyl ester (LNAME) during seven weeks, (iii) combined pulmonary embolisms and endothelial dysfunction (LNAME+Spheres), or (iv) served as sham-operated controls (Sham). Read More

    Effect of 6 weeks of high-intensity one-legged cycling on functional sympatholysis and ATP signaling in patients with heart failure.
    Am J Physiol Heart Circ Physiol 2017 Nov 22:ajpheart.00379.2017. Epub 2017 Nov 22.
    University of Southern Denmark.
    Breathlessness during daily activities is the primary symptom in patients with heart failure (HF). Poor correlation between the hemodynamic parameters of left ventricular performance and perceived symptoms suggests that other factors such as skeletal muscle function plays a role in determining exercise capacity. We investigated the effect of six weeks of high-intensity one-legged cycling (HIC; 8x4 at 90% one-legged cycling max) on: 1) the ability to override sympathetic vasoconstriction (arterial infusion of tyramine) during one-legged knee-extensor exercise (KEE); 2) vascular function (arterial infusion of ACh, SNP, tyramine and ATP); 3) exercise capacity in HF patients with reduced ejection fraction (n=8) compared with healthy individuals (n=6). Read More

    HEART RATE REDUCTION IMPROVES BIVENTRICULAR FUNCTION AND INTERACTIONS IN EXPERIMENTAL PULMONARY HYPERTENSION.
    Am J Physiol Heart Circ Physiol 2017 Nov 16:ajpheart.00493.2017. Epub 2017 Nov 16.
    Hospital for Sick Children
    Objectives: To investigate mechanisms of heart rate (HR) reduction on biventricular function and interactions in experimental pulmonary arterial hypertension (PAH).

    Methods: We compared cardiac-cycle mechanics and interventricular interactions in 15 sham, 8 monocrotaline-PAH, 9 PAH+carvedilol and 8 PAH+ivabradine rats. We used echocardiography to assess biventricular function, timing of cardiac- cycle events and septal position in PAH rats; and related HR reduction effect on biventricular function measured by echocardiography and conductance catheter. Read More

    A Novel Method for Quantitative Myocardial Contrast Echocardiography in Mice.
    Am J Physiol Heart Circ Physiol 2017 Nov 10:ajpheart.00568.2017. Epub 2017 Nov 10.
    UCSD
    The small size of the mouse heart frequently imparts technical challenges when applying conventional in vivo imaging methods for assessing heart function. Here we describe the use of high frequency ultrasound imaging in conjunction with a size-tuned blood pool contrast agent for quantitatively assessing myocardial perfusion in living mice. A perflurocarbon microbubble formulation exhibiting a narrow size distribution was developed, and echogenicity assessed at 18 MHz in vitro. Read More

    Protective Effects of the Mechanistic Target of Rapamycin against Excess Iron and Ferroptosis in Cardiomyocytes.
    Am J Physiol Heart Circ Physiol 2017 Nov 10:ajpheart.00452.2017. Epub 2017 Nov 10.
    University of Hawai'i
    Clinical studies suggest that myocardial iron is a risk factor for left ventricular remodeling in patients after myocardial infarction (MI). Ferroptosis was recently reported as a mechanism of iron-dependent non-apoptotic cell death. However, ferroptosis in the heart is not well understood. Read More

    Metaboreflex-mediated hemodynamic abnormalities in individuals with coronary artery disease without overt signs or symptoms of heart failure.
    Am J Physiol Heart Circ Physiol 2017 Nov 10:ajpheart.00436.2017. Epub 2017 Nov 10.
    University of Cagliari
    This study was devised to investigate the effect of coronary artery disease (CAD) without overt signs of heart failure on the cardiovascular responses to muscle metaboreflex activation. We hypothesized that any CAD-induced pre-clinical systolic and/or diastolic dysfunction could impair hemodynamic response to the metaboreflex test. Twelve males diagnosed with CAD without any sign or symptoms of heart failure and 11 age-matched healthy controls (CTL) participated in the study. Read More

    Structural and functional changes of the pulmonary vasculature after hypoxia exposure in the neonatal period - a new swine model of pulmonary vascular disease.
    Am J Physiol Heart Circ Physiol 2017 Nov 10:ajpheart.00362.2017. Epub 2017 Nov 10.
    Erasmus MC
    Pulmonary vascular disease (PVD) represents an underestimated and increasing clinical burden in the neonatal period, but also later in life, when exercise-tolerance is decreased. Animal models performing long-term follow-up after a perinatal insult are lacking. This study aimed to develop and characterize a neonatal swine model with hypoxia-induced PVD, during long-term follow-up after re-exposure to normoxia, and to investigate the exercise response in this model. Read More

    Cardiac performance is limited by oxygen delivery to the mitochondria in the crystalloid-perfused working heart.
    Am J Physiol Heart Circ Physiol 2017 Nov 10:ajpheart.00321.2017. Epub 2017 Nov 10.
    George Washington University.
    The left ventricular (LV) working, crystalloid-perfused heart is used extensively to evaluate basic cardiac function, pathophysiology, and pharmacology. Crystalloid-perfused hearts may be limited by oxygen delivery, as adding oxygen carriers increases myoglobin oxygenation and improves myocardial function. However, whether decreased myoglobin oxygen saturation impacts oxidative phosphorylation (OxPhos) is unresolved since myoglobin has a much lower affinity for oxygen than cytochrome c oxidase (COX). Read More

    PPARα agonists acutely inhibit calcium-independent PLA2 to reduce H2O2-induced contractions in aortae of spontaneously hypertensive rats.
    Am J Physiol Heart Circ Physiol 2017 Nov 10:ajpheart.00314.2017. Epub 2017 Nov 10.
    The University of Hong Kong
    Hypertension is associated with endothelial dysfunction, which favors the release of endothelium-derived contracting factors, including vasoconstrictor prostanoids and reactive oxygen species. Peroxisome proliferator-activated receptor α (PPARα) agonists, clinically used as lipid lowering drugs, possess antioxidant properties and exert beneficial effects in the vascular system. The present study aimed to identify the mechanism(s) underlying the acute effects of the PPARα agonists, Wy14643 and fenofibate, on endothelium-dependent contractions, in particular, those related to oxidative stress, in the aorta of the spontaneously hypertensive rat (SHR). Read More

    Vascular endothelial function masks increased sympathetic vasopressor activity in rats with metabolic syndrome.
    Am J Physiol Heart Circ Physiol 2017 Nov 10:ajpheart.00217.2017. Epub 2017 Nov 10.
    EA-4278 Dpt of Sciences, technologies and health
    Objective: Sympathetic hyperactivation, a common feature of obesity and metabolic syndrome, is a key trigger of hypertension. However, some obese subjects with autonomic unbalance present a dissociation between sympathetic activity mediated vasoconstriction and increased blood pressure. Here, we aimed to determine in a rat model of metabolic syndrome, whether the endothelium eNOS-NO pathway contribute to counteract the vasopressor effect of the sympathetic system. Read More

    Advanced oxidation protein products aggravate cardiac remodeling via cardiomyocyte apoptosis in chronic kidney disease.
    Am J Physiol Heart Circ Physiol 2017 Nov 3:ajpheart.00628.2016. Epub 2017 Nov 3.
    Sun Yat-sen Memorial Hospital of Sun Yat-sen University
    Advanced oxidation protein products (AOPPs) are independent risk factor for various cardiovascular diseases. Cardiomyocyte apoptosis has been implicated as an important mechanism in cardiac remodeling in chronic kidney disease (CKD). However, whether AOPPs affect cardiomyocyte apoptosis and subsequent cardiac remodeling in CKD is still not very clear. Read More

    Mechanism Underlying Heart Rate Dependency of Wave Reflection in the Aorta: A Numerical Simulation.
    Am J Physiol Heart Circ Physiol 2017 Nov 3:ajpheart.00559.2017. Epub 2017 Nov 3.
    Macquarie University
    Arterial wave reflection has been shown to have a significant dependence on heart rate (HR). However, the underlying mechanisms inherent in the HR dependency of wave reflection have not been well established. This study aimed to investigate the potential mechanisms and the role of arterial viscoelasticity using a 55-segment transmission line model (TLM) of the human arterial tree combined with a fractional viscoelastic model (FVM). Read More

    ENDOTHELIAL DYSFUNCTION IS A SUPER-INDUCER OF SYNDECAN 4: fibrogenic role of its ectodomain.
    Am J Physiol Heart Circ Physiol 2017 Nov 3:ajpheart.00548.2017. Epub 2017 Nov 3.
    New York Medical College.
    Syndecan 4 (Synd4) is a member of membrane-spanning, glycocalyx-forming proteoglycan family. It has been suggested that Synd4 participates in renal fibrosis. We compared wild type and fibrosis-prone endothelial sirtuin1-deficient (Sirt1(endo)-/-) mice, the latter being a model of global endothelial dysfunction. Read More

    Reduced Longitudinal Contraction is Associated with Ischemic Mitral Regurgitation after Posterior MI.
    Am J Physiol Heart Circ Physiol 2017 Nov 3:ajpheart.00546.2017. Epub 2017 Nov 3.
    Mount Sinai School of Medicine.
    Background: The role of left ventricular (LV) longitudinal contraction in ischemic mitral regurgitation (MR) remains unclear. We hypothesized that reduced longitudinal contraction disrupts normal mitral valve plane displacement during systole and leads to mitral valve tethering, thereby inducing ischemic MR.

    Methods: Twenty-three Yorkshire pigs underwent induction of different-sized posterior myocardial infarction (MI) using a percutaneous approach. Read More

    Reduced Membrane Cholesterol Following Chronic Hypoxia Limits Orai1-Mediated Pulmonary Endothelial Ca(2+) Entry.
    Am J Physiol Heart Circ Physiol 2017 Nov 3:ajpheart.00540.2017. Epub 2017 Nov 3.
    University of New Mexico Health Sciences Center
    Endothelial dysfunction in chronic hypoxia (CH)-induced pulmonary hypertension is characterized by reduced store-operated Ca(2+) entry (SOCE) and diminished Ca(2+)-dependent production of endothelium-derived vasodilators. We recently reported that SOCE in pulmonary arterial endothelial cells (PAEC) is tightly regulated by membrane cholesterol, and that decreased membrane cholesterol is responsible for impaired SOCE following CH. However, the ion channels involved in cholesterol-sensitive SOCE are unknown. Read More

    Heart Functional and Structural Compendium of Cardiosplenic and Cardiorenal Networks in Acute and Chronic Heart Failure Pathology.
    Am J Physiol Heart Circ Physiol 2017 Nov 3:ajpheart.00528.2017. Epub 2017 Nov 3.
    University of Alabama at Birmingham
    Heart failure (HF) secondary to myocardial infarction (MI) is linked to kidney complications that comprise cellular, structural, functional, and survival indicators. However, the HF research is focused on left ventricle (LV) pathology. Here, we determined the comprehensive functional analysis of LV using echocardiography in transition from acute HF (AHF) to progressive CHF pathology and develop a histological compendium of the cardiosplenic and cardiorenal networks in pathological remodeling. Read More

    A Novel Mitochondrial DNA Repair Enzyme Attenuates Maladaptive Remodeling and Preserves Cardiac Function in Heart Failure.
    Am J Physiol Heart Circ Physiol 2017 Nov 3:ajpheart.00515.2017. Epub 2017 Nov 3.
    LSU Health Sciences Center
    Background: Oxidative stress results in mitochondrial DNA (mtDNA) damage and contributes to myocardial cell death. mtDNA repair enzymes are crucial for mtDNA repair and cell survival. We investigated a novel, mitochondrial-targeted fusion protein (Exscien1-III) containing endonuclease III in myocardial ischemia/reperfusion (MI/Rep) injury and transverse aortic constriction (TAC) induced heart failure. Read More

    VEGF Nanoparticles Repair Heart after Myocardial Infarction.
    Am J Physiol Heart Circ Physiol 2017 Nov 3:ajpheart.00471.2017. Epub 2017 Nov 3.
    UAB
    Vascular endothelial growth factor (VEGF) is a well characterized pro-angiogenic cytokine that has been shown to promote neovascularization in the hearts of patients with ischemic heart disease but can also lead to adverse effects, depending on the dose and mode of delivery. We investigated whether prolonged exposure to a low dose of VEGF could be achieved by encapsulating the VEGF in polylactic-co-glycolic acid (PLGA) nanoparticles and whether treatment with VEGF-containing nanoparticles improved cardiac function and protected against left ventricular (LV) remodeling in the hearts of mice with experimentally induced myocardial infarction (MI). PLGA nanoparticles with a mean diameter of ~113 nm were generated via double emulsion and loaded with VEGF; the encapsulation efficiency was 53. Read More

    Loss of caveolin-3-dependent regulation of ICa in rat ventricular myocytes in heart failure.
    Am J Physiol Heart Circ Physiol 2017 Nov 3:ajpheart.00458.2017. Epub 2017 Nov 3.
    University of Bristol
    β2-adrenoceptors and the L-type Ca current (ICa) redistribute from the t-tubules to the surface membrane of ventricular myocytes from failing hearts. The present study investigated the role of changes in caveolin-3 (Cav-3) and protein kinase A (PKA) signaling, both of which have previously been implicated in this redistribution. ICa was recorded using the whole cell patch clamp technique from ventricular myocytes isolated from the hearts of rats that had undergone either coronary artery ligation (CAL) or equivalent Sham operation 18 weeks earlier. Read More

    Dietary Nitrate supplementation in Cardiovascular Health: An ergogenic aid or exercise therapeutic?
    Am J Physiol Heart Circ Physiol 2017 Nov 3:ajpheart.00414.2017. Epub 2017 Nov 3.
    Victoria University
    Oral consumption of inorganic nitrate, which is abundant in green leafy vegetables and roots, has been shown to increase circulating plasma nitrite concentration, which can be converted to NO in low oxygen conditions. The associated beneficial physiological effects include a reduction in blood pressure, modification of platelet aggregation and increases in limb blood flow. There have been numerous studies of nitrate supplementation in healthy recreational and competitive athletes, however, the ergogenic benefits are currently unclear due to a variety of factors including small sample sizes, different dosing regimens, variable nitrate conversion rates, the heterogeneity of participants' initial fitness levels and the types of exercise tests employed. Read More

    PH RECOVERY FROM A PROTON LOAD IN RAT CARDIOMYOCYTES: EFFECTS OF CHRONIC EXERCISE.
    Am J Physiol Heart Circ Physiol 2017 Nov 3:ajpheart.00405.2017. Epub 2017 Nov 3.
    Simon Fraser University
    The ability of cardiomyocytes to recover from a proton load was examined in the hearts of exercise-trained (T) and sedentary control (C) rats in CO2/HCO3--free media. Acidosis was created by the NH4Cl pre-pulse technique and pHi was determined using fluorescence microscopy on carboxy-SNARF-1 AM loaded isolated cardiomyocytes. CO2-independent intracellular pH buffering capacity (βi) was measured by incrementally reducing the [NH4Cl]o in steps of 50% from 20 to 1. Read More

    Flaxseed: Its Bioactive Components and their Cardiovascular Benefits.
    Am J Physiol Heart Circ Physiol 2017 Nov 3:ajpheart.00400.2017. Epub 2017 Nov 3.
    St. Boniface Hospital Research Centre
    Cardiovascular disease remains the leading cause of mortality and morbidity world-wide. The inclusion of functional foods and natural health products in the diet are gaining increasing recognition as integral components of lifestyle changes in the fight against cardiovascular disease. Several preclinical and clinical studies have shown the beneficial cardiovascular effects of dietary supplementation with flaxseed. Read More

    High-Intensity Interval Exercise Attenuates, but does not Eliminate, Endothelial Dysfunction after a Fast-Food Meal.
    Am J Physiol Heart Circ Physiol 2017 Nov 3:ajpheart.00384.2017. Epub 2017 Nov 3.
    Arizona State University
    We investigated whether two different bouts of high-intensity interval exercise (HIIE) could attenuate postprandial endothelial dysfunction. Thirteen young (27 ± 1 yr), non-exercise-trained men underwent 3 randomized conditions: (1) HIIE 4x4: four 4-min intervals at 85-95% of maximum heart rate (HRmax) separated by 3 min active recovery, (2) HIIE 16x1: 16 1-min intervals at 85%-95% of HRmax separated by 1 min active recovery, and (3) sedentary control. HIIE was performed in the afternoon, ~18 h prior to the morning fast-food meal (1250 kcal, 63g fat). Read More

    The Prorenin Receptor in the Cardiovascular System and Beyond.
    Am J Physiol Heart Circ Physiol 2017 Nov 3:ajpheart.00373.2017. Epub 2017 Nov 3.
    Tulane University, SOM
    Since the prorenin receptor (PRR) was first reported, investigations into its role in many cellular processes have been underway. Renin and prorenin binding to PRR and its soluble form (sPRR) increases angiotensin I formation and intracellular pathways resulting in induction of profibrotic factors. The PRR has supplementary roles as a vital accessory protein of the vacuolar-type H+-ATPase and also as an intermediate in Wnt signaling. Read More

    Voluntary apnea during dynamic exercise activates the muscle metaboreflex in humans.
    Am J Physiol Heart Circ Physiol 2017 Nov 3:ajpheart.00367.2017. Epub 2017 Nov 3.
    University of Tsukuba, Faculty of Health and Sport Sciences
    Voluntary apnea during dynamic exercise evokes marked bradycardia, peripheral vasoconstriction and pressor responses. However, the mechanism(s) underlying the cardiovascular responses seen during apnea in exercising humans is unknown. We therefore tested the hypothesis that the muscle metaboreflex contributes to the apnea-induced pressor response during dynamic exercise. Read More

    GENETICALLY INCREASED ANGIOTENSIN-I CONVERTING ENZYME ALTERS PERIPHERAL AND RENAL VASCULAR REACTIVITY TO ANGIOTENSIN II AND BRADYKININ IN MICE.
    Am J Physiol Heart Circ Physiol 2017 Nov 3:ajpheart.00356.2017. Epub 2017 Nov 3.
    INSERM U1138
    Angiotensin 1-converting enzyme (ACE) levels in man are under strong genetic influence. Genetic variation in ACE has been linked to risk for, and progression of, cardiovascular and renal diseases. Causality has been documented in genetically modified mice but mechanisms underlying causality are not completely elucidated. Read More

    Transient denervation of viable myocardium after myocardial infarction does not alter arrhythmia susceptibility.
    Am J Physiol Heart Circ Physiol 2017 Nov 3:ajpheart.00300.2017. Epub 2017 Nov 3.
    Oregon Health & Science University
    Cardiac sympathetic nerves stimulate heart rate and force of contraction. Myocardial infarction (MI) leads to the loss of sympathetic nerves within the heart, and clinical studies indicate that sympathetic denervation is a risk factor for arrhythmias and cardiac arrest. Two distinct types of denervation have been identified in the mouse heart after MI caused by ischemia-reperfusion: transient denervation of peri-infarct myocardium, and sustained denervation of the infarct. Read More

    Transcription factor ΔFosB acts within the nucleus of the solitary tract to increase mean arterial pressure during exposures to intermittent hypoxia.
    Am J Physiol Heart Circ Physiol 2017 Nov 3:ajpheart.00268.2017. Epub 2017 Nov 3.
    University of North Texas Health Science Center
    ΔFosB is a member of the AP-1 family of transcription factors. ΔFosB has low constitutive expression in the central nervous system and is induced following exposure of rodents to intermittent hypoxia (IH), a model of the arterial hypoxemia that accompanies sleep apnea. We hypothesize ΔFosB in the nucleus of solitary tract (NTS) contributes to increased mean arterial pressure (MAP) during IH. Read More

    Myocardial contrast echocardiography in mice: Technical and physiological aspects.
    Am J Physiol Heart Circ Physiol 2017 Nov 3:ajpheart.00242.2017. Epub 2017 Nov 3.
    VU University medical center
    Myocardial contrast echocardiography (MCE) offers the opportunity to study myocardial perfusion defects in mice in detail. The value of MCE compared to SPECT, PET and CT consists of high spatial resolution, the possibility of quantification of blood volume and relatively low costs. Nevertheless, a number of technical and physiological aspects should be considered to ensure reproducibility among research groups. Read More

    Mathematical Modeling Physiological Effects of the Overexpression of β2-Adrenoceptors in Mouse Ventricular Myocytes.
    Am J Physiol Heart Circ Physiol 2017 Nov 3:ajpheart.00160.2017. Epub 2017 Nov 3.
    Georgia State University
    Transgenic (TG) mice overexpressing β2-adrenergic receptors (β2-ARs) demonstrate enhanced myocardial function, which manifests in increased basal adenylyl cyclase activity, enhanced atrial contractility, and increased left ventricular function in vivo. To gain insights into the mechanisms of these effects, we developed a comprehensive mathematical model of the mouse ventricular myocyte overexpressing β2-ARs. We found that most of the β2-ARs are active in control conditions in TG mice. Read More

    Chronic femoral artery ligation exaggerates the pressor and sympathetic nerve responses during dynamic skeletal muscle stretch in decerebrate rats.
    Am J Physiol Heart Circ Physiol 2017 Oct 20:ajpheart.00498.2017. Epub 2017 Oct 20.
    Kansas State University
    Mechanical and metabolic signals arising during skeletal muscle contraction reflexly increase sympathetic nerve activity and blood pressure (i.e., the exercise pressor reflex). Read More

    Endothelial function is impaired in the cutaneous microcirculation of adults with psoriasis through reductions in nitric oxide-dependent vasodilation.
    Am J Physiol Heart Circ Physiol 2017 Oct 20:ajpheart.00446.2017. Epub 2017 Oct 20.
    The Pennsylvania State University.
    Psoriasis is an independent risk factor for cardiovascular disease, however the underlying mechanisms are not fully understood. Deficits in conduit arterial function are evident in psoriatics, but potential impairments in microcirculatory endothelial function remain unclear. We hypothesized that cutaneous microvascular dysfunction would be detectable in otherwise healthy psoriatics. Read More

    Carbohydrate-restriction with Postmeal Walking Effectively Mitigates Postprandial Hyperglycemia and Improves Endothelial Function in Type 2 Diabetes.
    Am J Physiol Heart Circ Physiol 2017 Oct 13:ajpheart.00524.2017. Epub 2017 Oct 13.
    University of British Columbia Okanagan
    Postprandial hyperglycemia has deleterious effects on endothelial function. Restricting carbohydrate intake and postmeal walking have each been shown to reduce postprandial hyperglycemia but their combination and subsequent effects on endothelial function have not been investigated. Here, we sought to examine the effect of blunting postprandial hyperglycemia by following a low-carbohydrate diet, with or without postmeal walking exercise, on markers of vascular health in type 2 diabetes (T2D). Read More

    The Sex-Specific Impact of Aging on the Blood Pressure Response to Exercise.
    Am J Physiol Heart Circ Physiol 2017 Oct 13:ajpheart.00505.2017. Epub 2017 Oct 13.
    University of Utah.
    An exaggerated blood pressure (BP) response to exercise has been linked to cardiovascular disease (CVD), but little is known about the impact of age and sex on this response. Therefore, this study examined the hemodynamic and skeletal muscle metabolic response to dynamic plantar flexion exercise, at 40% of WRmax, in 40 physical activity-matched young (n=20, 23±1 yr) and old (n=20, 73±2 yr), equally distributed, male and female subjects. Central hemodynamics and BP (finometer), popliteal artery (PA) blood flow (Doppler ultrasound), and skeletal muscle metabolism (phosphorous magnetic resonance spectroscopy, (31)P-MRS) were measured during 5 mins of plantar flexion exercise. Read More

    Macrophage overexpression of matrix metalloproteinase-9 in aged mice improves diastolic physiology and cardiac wound healing following myocardial infarction.
    Am J Physiol Heart Circ Physiol 2017 Oct 13:ajpheart.00453.2017. Epub 2017 Oct 13.
    University of Mississippi Medical Center
    Matrix metalloproteinase (MMP)-9 increases in the myocardium with advanced age and after MI. Because young transgenic (TG) mice overexpressing human MMP-9 only in macrophages mice show better outcomes post-MI, while aged TG mice show a worse aging phenotype, we wanted to evaluate the combination effect to see if the detrimental effect of aging counteracted the benefits of macrophage MMP-9 overexpression. We used 17-28 month old male and female C57BL/6J wild type (WT) mice and TG mice (n = 10-21/group) to evaluate the effects of aging superimposed on MI. Read More

    microRNA-206 correlates with left ventricular function after transcatheter aortic valve implantation (TAVI).
    Am J Physiol Heart Circ Physiol 2017 Oct 13:ajpheart.00432.2017. Epub 2017 Oct 13.
    Hannover Medical School
    Transcatheter aortic valve implantation (TAVI) is the method of choice in patients with high risk or contraindications for conventional aortic valve replacement. However, it is not well understood which parameters predict the overall cardiac function post- procedurally. MicroRNAs (miRNA/ miR) are small non-coding RNA molecules that repress gene expression by different mechanisms and can also be detected in the blood. Read More

    Muscle α-adrenergic responsiveness during exercise and ATP-induced vasodilation in chronic obstructive pulmonary disease patients.
    Am J Physiol Heart Circ Physiol 2017 Oct 13:ajpheart.00398.2017. Epub 2017 Oct 13.
    University of Southern Denmark.
    Sympathetic vasoconstriction is blunted in exercising muscle (functional sympatholysis) but becomes attenuated with age. We tested the hypothesis that functional sympatholysis is further impaired in chronic obstructive pulmonary disease (COPD) patients. We determined leg blood flow (LBF) and calculated leg vascular conductance (LVC) during 1) femoral-arterial Tyramine infusion (evokes endogenous norepinephrine release; 1 µmol min(-1) kg leg mass(-1)); 2) one-legged knee-extensor exercise with and without Tyramine infusion (10 W and 20% of maximal workload (WLmax)); 3) ATP (0. Read More

    Estrogen replacement attenuates stress-induced pressor responses through vasorelaxation via β2-adrenoceptor in peripheral arteries of ovariectomized rats.
    Am J Physiol Heart Circ Physiol 2017 Oct 13:ajpheart.00148.2017. Epub 2017 Oct 13.
    Faculty of Human Life and Environment, Nara Women's University
    We examined whether chronic estrogen replacement has an inhibitory effect on stress-induced pressor responses via activation of β2-adrenoceptor (AR) in peripheral arteries of ovariectomized rats. Female Wistar rats aged 9 weeks were ovariectomized. After 4 weeks, pellets containing either 17β-estradiol (E2) or placebo (Pla) were subcutaneously implanted into the rats. Read More

    HDL protects against doxorubicin induced cardiotoxicity in a scavenger receptor class B type 1, PI3K, and AKT dependent manner.
    Am J Physiol Heart Circ Physiol 2017 Oct 6:ajpheart.00521.2016. Epub 2017 Oct 6.
    McMaster University
    Doxorubicin is a widely used chemotherapeutic with deleterious cardiotoxic side effects. HDL has been shown to protect cardiomyocytes in vitro against doxorubicin-induced apoptosis. The scavenger receptor class B type I (SR-B1), a high affinity HDL receptor, mediates cytoprotective signaling by HDL through AKT. Read More

    Regulating MicroRNA Expression: At the Heart of Diabetes Mellitus and the Mitochondrion.
    Am J Physiol Heart Circ Physiol 2017 Oct 6:ajpheart.00520.2017. Epub 2017 Oct 6.
    West Virginia University School of Medicine
    Type 2 diabetes mellitus is a major risk factor for cardiovascular disease and mortality. Uncontrolled type 2 diabetes mellitus results in a systemic milieu of increased circulating glucose and fatty acids. The development of insulin resistance in cardiac tissue decreases cellular glucose import and enhances mitochondrial fatty acid uptake. Read More

    Exaggerated cardiovascular responses to treadmill running in rats with peripheral arterial insufficiency.
    Am J Physiol Heart Circ Physiol 2017 Oct 6:ajpheart.00401.2017. Epub 2017 Oct 6.
    Penn State College of Medicine
    Patients with atherosclerotic peripheral artery disease (PAD) have an augmented pressor response to treadmill walking, but the underlying mechanisms remain poorly understood and difficult to isolate due to the confounding presence of numerous cardiovascular risk factors. In this study, we tested the hypothesis that a chronic deficit in muscle blood flow capacity would be sufficient to trigger an exaggerated pressor response to dynamic exercise. Sprague Dawley rats (5 male, 5 female) were instrumented with radiotelemetery devices in order to measure the cardiovascular responses to treadmill running before and after bilateral femoral artery ligation, which has been shown previously to reduce the blood flow capacity of the distal hindlimb muscles by >60%. Read More

    Dual effects of hyperglycemia on endothelial cells and cardiomyocytes to enhance coronary LPL activity.
    Am J Physiol Heart Circ Physiol 2017 Oct 6:ajpheart.00372.2017. Epub 2017 Oct 6.
    University of British Columbia
    In the diabetic heart, there is excessive dependence on FA utilization to generate ATP. Lipoprotein lipase (LPL)-mediated hydrolysis of circulating triglyceride (TG) is suggested to be the predominant source of FA for cardiac utilization during diabetes. In the heart, majority of LPL is synthesized in cardiomyocytes, and secreted onto cell surface heparan sulfate proteoglycans (HSPG), where an endothelial cell (EC) releasable β-endoglycosidase, heparanase, cleaves the side chains of HSPG to liberate LPL for its onward movement across the EC. Read More

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