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PubMed Journal Database | American journal of physiology. Heart and circulatory physiology RSS

18:29 EST 22nd November 2019 | BioPortfolio

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Showing PubMed Articles 1–25 of 501 from American journal of physiology. Heart and circulatory physiology

Bimodal Right Ventricular Dysfunction After Postnatal Hyperoxia Exposure: Implications for the Preterm Heart.

Rats exposed to postnatal hyperoxia develop right ventricular (RV) dysfunction, mild pulmonary hypertension, and dysregulated cardiac mitochondrial biogenesis when aged to 1 year, with the degree of cardiac dysfunction and pulmonary hypertension similar to that previously described in young adults born preterm. Here, we sought to understand the impact of postnatal hyperoxia exposure on RV hemodynamic and mitochondrial function across the lifespan.

Clinical safety of blood flow restricted training? A comprehensive review of altered muscle metaboreflex in cardiovascular disease during ischemic exercise.

Blood flow restriction training (BFRT) is an increasingly widespread method of exercise that involves imposed restriction of blood flow to the exercising muscle. Blood flow restriction is achieved by inflating a pneumatic pressure cuff (or a tourniquet) positioned proximal to the exercising muscle prior to, and during, the bout of exercise (i.e., ischemic exercise). Low-intensity BFRT with resistance training promotes comparable increases in muscle mass and strength observed during high-intensity exercise w...

A Novel Methodology for Rat Aortic Pulse Wave Velocity Assessment by Doppler Ultrasound: Validation against Invasive Measurements.

There is still lack of a simple, accurate and noninvasive method for rat aortic pulse wave velocity (PWV) measurement, especially the transit distance cannot be accurately measured. Thus we aimed to derive an equation for aortic transit distance as a function of the nose-to-rump length (L), and to test the hypothesis that aortic PWV measured by new equation combined with Doppler ultrasound (the "equation method") may have stronger correlation with invasive measurements than traditional "body surface method"...

Adaptive Immunity Driven Inflammation and Cardiovascular Disease.

The adaptive immune response has recently emerged as an important factor in a wide variety of cardiovascular disorders including atherosclerosis, hypertension, cardiac remodeling, and heart failure; however, its role is not fully understood. Since an assortment of innate responsive cells (e.g. neutrophils, monocytes/macrophages) coordinate with adaptive immunity (e.g. T-cells, dendritic cells, B-cells), the temporal response and descriptions pertinent to the cellular phenotype, and inflammation processes in...

Disentangling the Gordian knot of local metabolic control of coronary blood flow.

Recognition that coronary blood flow is tightly coupled with myocardial metabolism has been appreciated for well over half a century. However, exactly how coronary microvascular resistance is tightly coupled with myocardial oxygen consumption (MVO) remains one of (if not) the most highly contested mysteries of the coronary circulation to this day. Understanding the mechanisms responsible for local metabolic control of coronary blood flow has been confounded by continued debate regarding both anticipated exp...

Computational quantification of patient specific changes in ventricular dynamics associated with pulmonary hypertension.

Pulmonary arterial hypertension causes an increase in the mechanical loading imposed on the right ventricle that results in progressive changes to its mechanics and function. Here, we quantify the mechanical changes associated with PAH by assimiliating clinical data consisting of reconstructed 3D geometry, pressure and volume waveforms as well as regional strains measured in PAH patients (n = 12) and controls (n = 6) within a computational modeling framework of the ventricles. Modeling parameters reflecting...

Acute reduction in cerebral blood velocity on supine-to-stand transition increases postural instability in young adults.

We tested the hypothesis that transient deficits in cerebral blood flow are associated with postural sway. In 19 young healthy adults, we examined the association between the drop in cerebral blood flow during supine-to-stand transitions (indexed by transcranial Doppler ultrasound (middle cerebral artery blood velocity at diastole; MCAdv) and near-infrared spectroscopy (tissue saturation index; TSI)) and the center of pressure displacement while standing. Participants performed transitions under 3 condition...

Cardiac ischemia/reperfusion injury induces ROS-dependent loss of PKA regulatory subunit RIα.

Type I PKA regulatory subunit alpha (RIα; encoded by the Prkar1a gene) serves as the predominant inhibitor protein of the catalytic subunit of cAMP-dependent protein kinase (PKAc). However, recent evidence suggests that PKA signaling can be initiated by cAMP-independent events, especially within the context of cellular oxidative stress such as ischemia/reperfusion (I/R) injury. We determined whether RIα is actively involved in the regulation of PKA activity via Reactive Oxygen Species (ROS) dependent mech...

Hemodynamic effects of myocardial bridging in patients with hypertrophic cardiomyopathy.

Myocardial bridging (MB) is linked to angina and myocardial ischemia and may lead to sudden cardiac death in patients with hypertrophic cardiomyopathy (HCM). However, it remains unclear how MB affect the coronary blood flow in HCM patients. The aim of this study was to assess the effects of MB on coronary hemodynamics in HCM patients. Fifteen patients with MB (7 HCM and 8 non-HCM controls) in their left anterior descending (LAD) coronary artery were chosen. Transient computational fluid dynamics (CFD) simul...

Using velocity-pressure loops in the operating room: a new approach of arterial mechanics for cardiac afterload monitoring under general anesthesia.

Cardiac afterload is usually assessed in the ascending aorta and can be defined by the association of peripheral vascular resistance (PVR), total arterial compliance (Ctot) and aortic wave reflection (WR). We recently proposed the global afterload angle (GALA) and beta angle derived from the aortic velocity-pressure loop (VP loop) as continuous cardiac afterload monitoring in the descending thoracic aorta. The aim of this study was: (1) to describe the arterial mechanic properties by studying the velocity-p...

ASIC1a plays a key role in evoking the metabolic component of the exercise pressor reflex in rats.

The role of the acid-sensing ion channel 1a (ASIC1a) in evoking the exercise pressor reflex is unknown despite the fact that ASIC1a is opened by decreases in pH in the physiological range. This fact prompted us to test the hypothesis that ASIC1a plays an important role in evoking the exercise pressor reflex in decerebrated rats with freely perfused hindlimb muscles. To test this hypothesis, we measured the effect of injecting two ASIC1a blockers into the arterial supply of the triceps surae muscles on the r...

Caspase Lesions of PVN-Projecting MnPO Neurons Blocks the Sustained Component of CIH-Induced Hypertension in Adult Male Rats.

Obstructive Sleep Apnea is characterized by interrupted breathing that leads to cardiovascular sequelae including chronic hypertension that can persist into waking hours. Chronic intermittent hypoxia, which models the hypoxemia associated with sleep apnea, is sufficient to cause a sustained increase in blood pressure that involves the central nervous system. The median preoptic nucleus (MnPO) is an integrative forebrain region that contributes to blood pressure regulation and neurogenic hypertension. The Mn...

SYMPATHETIC BAROREFLEX SENSITIVITY IS INVERSELY RELATED TO VASCULAR TRANSDUCTION IN MALES BUT NOT FEMALES.

Sympathetic baroreflex sensitivity (BRS) is a measure of how effectively the baroreflex buffers beat-to-beat changes in blood pressure through the modulation of muscle sympathetic nerve activity (MSNA). However, current methods of assessment do not take into account the transduction of sympathetic nerve activity at the level of the vasculature, which is known to vary between individuals. In this study we tested the hypothesis that there is an inverse relationship between sympathetic BRS and vascular transdu...

Maternal microbiome and the hypertensive disorder of pregnancy, preeclampsia.

Preeclampsia (PE) is a pregnancy specific disorder that can be life threatening for both mother and baby. It is characterized by new onset hypertension during the second half of pregnancy and affects approximately 300,000 women in the United States every year. There is no cure for PE and the only effective treatment is delivery of the placenta and the fetus, which is often preterm. PE is believed to be a severe manifestation of placental dysfunction due to early angiogenic imbalances and inflammatory distur...

A Critical Appraisal of the Tafazzin Knockdown Mouse Model of Barth Syndrome: What Have We Learned About Pathogenesis and Potential Treatments?

Pediatric heart failure remains poorly understood, distinct in many aspects from adult heart failure. Limited data point to roles of altered mitochondrial functioning and in particular, changes in mitochondrial lipids, especially cardiolipin. Barth syndrome is a mitochondrial disorder caused by tafazzin mutations that lead to abnormal cardiolipin profiles. Patients are afflicted by cardiomyopathy, skeletal myopathy, neutropenia, and growth delay. A mouse model of Barth syndrome was developed a decade ago, w...

SUMO2 regulates vascular endothelial function and oxidative stress in mice.

SUMOylation is a post-translational modification of lysine residues. Modification of proteins by SUMO1, 2, and 3 can achieve varied, and often unique, physiological and pathological effects. We looked for SUMO2-specific effects on vascular endothelial function. SUMO2 expression was upregulated in the aortic endothelium of hypercholesterolemic LDLr mice and was responsible for impairment of endothelium-dependent vasorelaxation in these mice. Moreover, overexpression of SUMO2 in aortas , in cultured endotheli...

Salt restriction lowers blood pressure at rest and during exercise without altering peripheral hemodynamics in hypertensive individuals.

Dietary salt restriction is a well-established approach to lower blood pressure and reduce cardiovascular disease risk in hypertensive individuals. However, little is currently known regarding the effects of salt restriction on central and peripheral hemodynamic responses to exercise in those with hypertension. Therefore, this study sought to determine the impact of salt restriction on the central and peripheral hemodynamic responses to static-intermittent handgrip (HG) and dynamic single-leg knee extension...

A 4D Flow MRI Evaluation of the Impact of Shear-Dependent Fluid Viscosity on in vitro Fontan Circulation Flow.

The Fontan procedure for univentricular heart defects creates a non-physiologic circulation where systemic venous blood drains directly into the pulmonary arteries, leading to multiorgan dysfunction secondary to chronic low-shear non-pulsatile pulmonary blood flow and central venous hypertension. Although blood viscosity increases exponentially in this low-shear environment, the role of shear-dependent ("non-Newtonian") blood viscosity in this pathophysiology is unclear. We studied 3D-printed Fontan models ...

Sodium, Hypertension, and the Gut: Does the Gut Microbiota Go Salty?

Recent evidence suggests the gut microbiota contributes to the pathogenesis of hypertension (HTN). The gut microbiota is a highly dynamic organ mediating numerous physiological functions, which can be influenced by external factors such as diet. In particular, a major modifiable risk factor for HTN is dietary sodium intake. Sodium consumption in the United States is significantly greater than recommended by the federal government and organizations such as the American Heart Association. Due to the emerging ...

Gravin Gravitates Atherogenesis to Atheroprogression in the Obesogenic Setting.

PAPP-A and the IGF system in Atherosclerosis - What's Up, What's Down?

Pregnancy-associated plasma protein-A (PAPP-A) is a metalloproteinase with a well-established role in releasing bioactive insulin-like growth factor 1 (IGF1) from IGF binding protein 2, -4 and -5 by proteolytic processing of these. The IGF system has repeatedly been suggested to be involved in the pathology of atherosclerosis, and both PAPP-A and IGF1 are proposed biomarkers and therapeutic targets for this disease. Several experimental approaches based on atherosclerosis mouse models have been undertaken t...

Venous return and the physical connection between distribution of segmental pressures and volumes.

More than sixty years ago, Guyton and co-workers related their observations of venous return to a mathematical model. Showing steady state flow (F) as proportional to the difference between mean systemic pressure, (Pms), and right atrial pressure, (Pra), the model fit their data. The parameter defined by the ratio (Pms - Pra)/F, first called an "impedance", came to be called the "resistance to venous return." The interpretation, that Pra opposes Pms and that, to increase output, the heart must act to reduce...

Impaired function of aorta and perivascular adipose tissue in IL-18-deficient mice.

Interleukin-18 (IL-18) is ubiquitously produced by both hematopoietic and non-hematopoietic cells, but the central biological role of IL-18 in non-hematopoietic cells has not been sufficiently elucidated. In the present study, we examined the thoracic aorta, including perivascular adipose tissue (PVAT) of the IL-18 knockout (KO) mice in terms of functional and histological aspects. IL-18KO mice exhibited significantly higher blood pressure compared with wild-type (WT) mice. Echocardiographic examination s...

Thymine DNA Glycosylase (TDG) is a Key Regulator of CaMKIIγ Expression and Vascular Smooth Muscle Phenotype.

Multifunctional Ca/calmodulin-dependent protein kinase II (CaMKII) is a multi-gene family with isoform-specific regulation of vascular smooth muscle (VSM) functions. In previous studies we found that vascular injury resulted in VSM de-differentiation and reduced expression of the CaMKIIg isoform in medial wall VSM. Smooth muscle knockout of CaMKIIg enhanced injury-induced VSM neointimal hyperplasia whereas CaMKIIg over-expression inhibited VSM proliferation and neointimal formation. In this study, we evalua...

Modelling arterial pulse waves in healthy ageing: a database for in silico evaluation of haemodynamics and pulse wave indices.

The arterial pulse wave (PW) is a rich source of information on cardiovascular (CV) health. It is widely measured by both consumer and clinical devices. However, the physical determinants of the PW are not yet fully understood, and the development of PW analysis algorithms is limited by a lack of PW datasets containing reference CV measurements. Our aim was to create a database of PWs simulated by a computer to span a range of CV conditions, representative of a sample of healthy adults. The typical CV prope...


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