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American Journal of Physiology. Heart and Circulatory Physiology

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https://www.readbyqxmd.com/read/28213406/mitochondria-regulated-formation-of-endothelial-extracellular-vesicles-shifts-the-mediator-of-flow-induced-vasodilation
#1
Julie K Freed, Matthew J Durand, Brian Robert Hoffmann, John C Densmore, Andrew S Greene, David D Gutterman
In order to examine the effect of endothelial-derived extracellular vesicles (eEVs) on the mechanism of flow-induced dilation (FID) composition, formation, and functional effects on the mechanism of FID were examined from two different eEV subtypes, one produced from ceramide, the other from plasminogen-activator inhibitor 1 (PAI-1). Using videomicroscopy, internal diameter changes in response to increases in flow were measured in human adipose resistance arteries acutely exposed (30min) to eEVs derived from cultured endothelial cells exposed to ceramide or PAI-1...
February 17, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28213405/inhibition-of-the-mtor-pathway-in-abdominal-aortic-aneurysm-implication-of-smooth-muscle-cell-contractile-phenotype-inflammation-and-aneurysm-expansion
#2
Guangxin Li, Lingfeng Qin, Lei Wang, Xuan Li, Alexander W Caulk, Jian Zhang, Pei-Yu Chen, Shijie Xin
The development of effective pharmacological treatment of abdominal aortic aneurysm (AAA) potentially offers great benefit to patients with pre-aneurysmal aortic dilation by slowing the expansion of aneurysms and reducing the need for surgery. To date, therapeutic targets for slowing aortic dilation have had low efficacy. Thus, in this study, we aim to elucidate possible mechanisms driving aneurysm progression in order to identify potential targets for pharmacological intervention. We demonstrate that mTOR signaling is over activated in aortic smooth muscle cells (SMCs) which contributes to murine AAA...
February 17, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28213404/hydrogen-sulfide-alleviates-hypertensive-kidney-dysfunction-through-an-epigenetic-mechanism
#3
Gregory Weber, Sathnur Pushpakumar, Utpal Sen
Hypertension is a major risk factor for chronic kidney disease (CKD) and renal inflammation is an integral part in this pathology. Hydrogen sulfide (H2S) has been shown to mitigate renal damage through reduction in blood pressure and reactive oxygen species; however, the exact mechanisms are not clear. While several studies have underlined the role of epigenetics in renal inflammation and dysfunction, the mechanisms through which epigenetic regulators play role in hypertension are not well defined. In this study, we sought to identify if microRNAs are dysregulated in response to angiotensin-II (Ang-II) induced hypertension in the kidney and whether H2S donor, GYY 4137, could reverse the microRNA alteration and kidney function...
February 17, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28213403/temporal-dissociation-between-minimal-distal-to-aortic-pressure-ratio-and-peak-hyperemia-during-intravenous-adenosine-infusion
#4
Lorena Casadonte, Koen M Marques, Jos Ae Spaan, Maria Siebes
The present study sought to compare the temporal relation between maximal coronary flow (peak hyperemia) and minimal coronary/aortic (Pd/Pa) pressure ratio for intracoronary (IC) and intravenous (IV) adenosine administration. Peak hyperemia is assumed to coincide with the minimal Pd/Pa value. However, this has not been confirmed for systemic hemodynamic variations during IV adenosine infusion. Hemodynamic responses to IV and IC adenosine administration were obtained in 12 patients (14 lesions) using combined intracoronary pressure and flow velocity measurements...
February 17, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28213402/a-novel-method-of-standardized-myocardial-infarction-in-aged-rabbits
#5
Patrick J Morrissey, Kevin R Murphy, Jean M Daley, Lorraine Schofield, Nilufer N Turan, Karuppiah Arunachalam, J Dawn Abbott, Gideon Koren
The incidence of myocardial infarction (MI) and sudden cardiac death increases with age. Here we describe the development of a minimally invasive large animal model of MI that can be applied to young or aged animals. We demonstrate that rabbit coronary anatomy is highly variable, more so than described in previous literature. In this work we categorize the coronary pattern of 37 young and 63 aged rabbits. Aged rabbits had a higher degree of branching from the left main coronary artery. Standardizing the model across age cohorts required a new approach, targeting an area of myocardium rather than a specific vessel...
February 17, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28188215/cystathionine-gamma-lyase-protects-vascular-endothelium-a-role-for-inhibition-of-histone-deacetylase-6
#6
Thorsten Martin Leucker, Yohei Nomura, Jae Hyung Kim, Anil Bhatta, Victor Wang, Andrea Wecker, Sandeep S Jandu, Lakshmi Santhanam, Dan E Berkowitz, Lewis Romer, Deepesh Pandey
Endothelial cystathionine -lyase (CSE) contributes to cardiovascular homeostasis, mainly through production of hydrogen sulfide. However, the molecular mechanisms that control CSE gene expression in endothelium during cardiovascular diseases are unclear. The aim of the current study is to determine the role of specific histone deacetylases (HDAC) in the regulation of endothelial CSE. Reduced CSE mRNA expression and protein abundance were observed in human aortic endothelial cells (HAEC) exposed to OxLDL and in aortas from atherogenic ApoE-/- mice fed a high-fat diet as compared with controls...
February 10, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28188214/transcranial-doppler-determined-change-in-posterior-cerebral-artery-blood-flow-velocity-does-not-reflect-vertebral-artery-blood-flow-during-exercise
#7
Takuro Washio, Hiroyuki Sasaki, Shigehiko Ogoh
We examined whether a change in posterior cerebral artery flow velocity (PCAv) reflected the posterior cerebral blood flow, in healthy subjects, during both static and dynamic exercise. PCAv and vertebral artery (VA) blood flow, as an index of posterior blood flow, were continuously measured during an exercise trial, using transcranial Doppler (TCD) ultrasonography and Doppler ultrasound, respectively. Static handgrip exercise significantly increased both PCAv and VA blood flow. Increasing intensity of dynamic exercise further increased VA blood flow from moderate exercise, while PCAv decreased to almost resting level...
February 10, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28188213/non-invasive-stratification-of-postinfarction-rats-based-on-degree-of-cardiac-dysfunction-using-magnetic-resonance-imaging-and-echocardiography
#8
Jan Magnus Aronsen, Emil Knut Stenersen Espe, Kristine Skårdal, Almira Hasic, Lili Zhang, Ivar Sjaastad
The myocardial infarction (MI) rat model plays a crucial role in modern cardiovascular research, but the inherent heterogeneity of this model represents a challenge. We sought to identify subgroups among the post-MI rats, and establish simple non-invasive stratification protocols for such subgroups. Six weeks after induction of MI, 49 rats underwent non-invasive examinations using magnetic resonance imaging (MRI) and echocardiography. 12 sham-operated rats served as controls. Increased end-diastolic left ventricular (LV) pressure and lung weight served as indicators for congestive heart failure (CHF)...
February 10, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28188212/ventricular-tachycardia-in-ischemic-heart-disease-the-sympathetic-heart-and-its-scars
#9
Christian Meyer, Katharina Scherschel
N/A.
February 10, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28159812/right-ventricular-metabolism-during-veno-arterial-extracorporeal-membrane-oxygenation-in-immature-swine-heart-in-vivo
#10
Masaki Kajimoto, Dolena R Ledee, Nancy G Isern, Michael A Portman
Veno-arterial extracorporeal membrane oxygenation (VA-ECMO) provides hemodynamic rescue for patients encountering right or left ventricular (RV or LV) decompensation, particularly after surgery for congenital heart defects. ECMO, supported metabolically by parenteral nutrition, provides reductions in myocardial work and energy demand and therefore enhances functional recovery. The RV must often assume systemic ventricular pressures and function upon weaning from VA-ECMO. However the substrate utilization responses of the RV to VA-ECMO or stimulation are unknown...
February 3, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28159811/using-heat-as-a-therapeutic-tool-for-the-aging-vascular-tree
#11
Ryan McGinn, Martin P Poirier, Glen P Kenny
Healthy aging in humans is associated with progressive deterioration of various organ systems, the cardiovascular system being one of the most notable. Young arteries have a pronounced ability to dilate and constrict to mediate changes in blood flow in response to various stimuli (e.g. exposure to a cold or hot environment). With increasing age, complex structural and functional changes to the blood vessels occur which are further exacerbated by common comorbidities including hypertension, diabetes mellitus and hypercholesterolemia...
February 3, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28159810/impaired-peripheral-vasodilation-during-graded-systemic-hypoxia-in-healthy-older-adults-role-of-the-sympathoadrenal-system
#12
Jennifer C Richards, Anne R Crecelius, Dennis G Larson, Gary J Luckasen, Frank A Dinenno
Systemic hypoxia is a physiological and pathophysiological stress that activates the sympathoadrenal system and, in young adults, leads to peripheral vasodilation. We tested the hypothesis that peripheral vasodilation to graded systemic hypoxia is impaired in older healthy adults and that this age-associated impairment is due to attenuated β-adrenergic mediated vasodilation and elevated α-adrenergic vasoconstriction. Forearm blood flow was measured (Doppler ultrasound) and vascular conductance (FVC) was calculated in 12 young (24±1 yrs) and 10 older (63±2 yrs) adults to determine the local dilatory responses to graded hypoxia (90, 85, and 80% O2 saturations) in control conditions, following local intra-arterial blockade of β-receptors (propranolol), and combined blockade of α+β receptors (phentolamine + propranolol)...
February 3, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28159809/cardiac-med1-deletion-promotes-early-lethality-cardiac-remodeling-and-transcriptional-reprogramming
#13
Kathryn M Spitler, Jessica M Ponce, Gavin Y Oudit, Duane D Hall, Chad E Grueter
The Mediator complex, a multisubunit nuclear complex, plays an integral role in regulating gene expression by acting as a bridge between transcription factors and RNA polymerase II. Genetic deletion of mediator subunit 1 (Med1) results in embryonic lethality, due in large part to impaired cardiac development. We first established that Med1 is dynamically expressed in cardiac development and disease, with marked upregulation of Med1 in both human and murine failing hearts. To determine if Med1 deficiency protects against cardiac stress, we generated two cardiac-specific Med1 knockout mouse models in which Med1 is conditionally deleted (Med1cKO mice) or inducibly deleted in adult mice (Med1cKO-MCM mice)...
February 3, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28159808/optogenetic-identification-of-hypothalamic-orexin-neuron-projections-to-paraventricular-spinally-projecting-neurons
#14
Olga Dergacheva, Akihiro Yamanaka, Alan R Schwartz, Vsevolod Y Polotsky, David Mendelowitz
Orexin neurons, and activation of orexin receptors, are generally thought to be sympathoexcitatory; however, the functional connectivity between orexin neurons and a likely sympathetic target, the hypothalamic spinally-projecting neurons (SPNs) in the paraventricular nucleus of the hypothalamus (PVN), has not been established. To test the hypothesis that orexin neurons project directly to SPNs in the PVN, channelrhodopsin-2 (ChR2) was selectively expressed in orexin neurons to enable photoactivation of ChR2-expressing fibers while examining evoked postsynaptic currents in SPNs in rat hypothalamic slices...
February 3, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28159807/resveratrol-improves-exercise-performance-and-skeletal-muscle-oxidative-capacity-in-heart-failure
#15
Miranda M Sung, Nikole J Byrne, Ian M Robertson, Ty T Kim, Victor Samokhvalov, Jody Levasseur, Carrie-Lynn M Soltys, David Fung, Neil Tyreman, Emmanuel Denou, Kelvin Jones, John M Seubert, Jonathan D Schertzer, Jason R B Dyck
We investigated whether treatment of mice with established pressure overload-induced heart failure (HF) with the naturally occurring polyphenol resveratrol could improve functional symptoms of clinical HF such as fatigue and exercise intolerance. C57Bl/6N mice were subjected to either sham or transverse aortic constriction surgery to induce HF. Three weeks post-surgery, a cohort of mice with established HF (% ejection fraction; %EF<45) was administered resveratrol (~450 mg/kg/d) or vehicle for 2 weeks. Although %EF was similar between both groups of HF mice, those mice treated with resveratrol had increased total physical activity levels and exercise capacity...
February 3, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28159806/oscillatory-lower-body-negative-pressure-impairs-working-memory-task-related-functional-hyperemia-in-healthy-volunteers
#16
Sana Merchant, Marvin S Medow, Paul Visintainer, Courtney Terilli, Julian M Stewart
Neurovascular coupling (NVC) describes the link between an increase in task related neural activity and increased cerebral blood flow denoted "functional hyperemia". We previously showed induced cerebral blood flow oscillations suppressed functional hyperemia; conversely functional hyperemia also suppressed cerebral blood flow oscillations. We used lower body negative pressure (OLBNP) oscillations to force oscillations in middle cerebral artery cerebral blood flow velocity (CBFv). Here, we used N-Back testing, an intellectual memory challenge as a neural activation task, to test the hypothesis that OLBNP-induced oscillatory cerebral blood flow (OCBF) can reduce functional hyperemia and NVC produced by a working memory task, and can interfere with working memory...
February 3, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28130342/nfat-regulation-of-cystathionine-gamma-lyase-expression-in-endothelial-cells-is-impaired-in-rats-exposed-to-intermittent-hypoxia
#17
Laura V Gonzalez Bosc, Jessica M Osmond, Wieslawa Giermakowska, Carolyn E Pace, Jennifer L Riggs, Olan Jackson-Weaver, Nancy L Kanagy
Sleep apnea is a risk factor for cardiovascular disease, and intermittent hypoxia (IH, 20 episodes/hr of 5% O2/5% CO2 for 7 hr/day) to mimic sleep apnea increases blood pressure and impairs H2S-induced vasodilation in rats. The enzyme that produces H2S, cystathionine gamma lyase (CSE), is decreased in rat mesenteric artery endothelial cells (EC) following in vivo IH exposure. In silico analysis identified putative NFAT binding sites in the CSE promoter. Therefore, we hypothesized that IH exposure reduces [Ca(2+)] activation of calcineurin/NFAT to lower CSE expression and impairs vasodilation...
January 27, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28130341/the-history-of-the-microsphere-method-for-measuring-blood-flows-with-special-reference-to-myocardial-blood-flow-a-personal-memoir
#18
Julien I E Hoffman
We use many types of equipment and technologies to make our measurements, but give little thought to how they developed. Evolution was once described as a series of recoils from blind alleys, and this is exemplified by the gradual development of the microsphere method of measuring blood flows. The microsphere method is one of the most frequently used methods for measuring blood flow to organs and portions of organs. The method can measure myocardial blood flow with reasonable accuracy (within 10%) down to samples weighing >50mg but probably will not do so for samples weighing 1-10 mg...
January 27, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28130340/influence-of-sex-on-microvascular-and-macrovascular-responses-to-prolonged-sitting
#19
Jennifer R Vranish, Benjamin E Young, Jasdeep Kaur, Jordan C Patik, Jaume Padilla, Paul J Fadel
Increased daily sitting time is associated with greater cardiovascular risk, and on average women are more sedentary than men. Recent reports have demonstrated that prolonged sitting reduces lower leg microvascular (reactive hyperemia) and macrovascular (flow-mediated dilation, FMD) vasodilator function. However, these studies have predominately included men, and the effects of sitting in young women are largely unexplored. This becomes important given known sex differences in vascular function. Thus herein, we assessed popliteal artery reactive hyperemia and FMD, before and after a 3hr sitting period, in healthy young women (n=12) and men (n=8)...
January 27, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28130339/evidence-for-hysteresis-in-the-cerebral-pressure-flow-relationship-in-healthy-men
#20
Patrice Brassard, Hélène Ferland-Dutil, Jonathan David Smirl, Myriam Paquette, Olivier Le Blanc, Simon Malenfant, Philip N Ainslie
The cerebrovasculature is more efficient at compensating for pharmacologically induced transient hypertension versus transient hypotension. Whether this phenomenon exists during non-pharmacologically hypertension and hypotension is currently unknown. We compared the % change in mean velocity in the middle cerebral artery (MCAvmean), per % change in mean arterial pressure (MAP) (%MCAVmean/%MAP) during transient hypertension and hypotension induced during squat-stand manoeuvres performed at 0.05 (20 second cycles) and 0...
January 27, 2017: American Journal of Physiology. Heart and Circulatory Physiology
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