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PubMed Journal Database | American journal of physiology. Heart and circulatory physiology - Page: 20 RSS

13:36 EST 7th December 2019 | BioPortfolio

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Showing PubMed Articles 476–500 of 509 from American journal of physiology. Heart and circulatory physiology

Acute exposure to progesterone attenuates cardiac contraction by modifying myofilament calcium sensitivity in the female mouse heart.

Acute application of progesterone attenuates cardiac contraction, although the underlying mechanisms are unclear. We investigated whether progesterone modified contraction in isolated ventricular myocytes and identified the Ca(2+) handling mechanisms involved in female C57BL/6 mice (6-9 mos; sodium pentobarbital anesthesia). Cells were field-stimulated (4 Hz; 37°C) and exposed to progesterone (0.001-10.0 μM) or vehicle (35 mins). Ca(2+) transients (fura-2) and cell shortening were recorded simultaneously....

Investigating the extremes of the continuum of paracrine functions in CD34-/CD31+ CACs across diverse populations.

Paracrine function of circulating angiogenic cells (CACs) is thought to contribute to vascular maintenance. We previously identified S100A8 and S100A9 secreted from physically inactive individuals' CD34-/CD31+ CACs as negative regulators of capillary-like network formation. The purpose of this study was to further investigate the extremes of the continuum of CAC paracrine actions using two distinctly different groups representing "healthy" and "impaired" CAC function. We aimed to determine how capillary-lik...

Myocardial interstitial levels of serotonin and its major metabolite 5-hydroxyindole acetic acid during ischemia-reperfusion.

The aim of this study was to examine the accumulation of serotonin (5-HT) and degradation of 5-HT taken up into cells in the ischemic region during myocardial ischemia-reperfusion. Using microdialysis technique in anesthetized rats, we monitored myocardial interstitial levels of 5-HT and its metabolite produced by monoamine oxidase (MAO), 5-hydroxyindole acetic acid (5-HIAA), during 30-min coronary occlusion followed by 45-min reperfusion, and investigated the effects of local administration of the MAO inhi...

Functional Vascular Contributions to Cognitive Impairment and Dementia (VCID): Mechanisms and Consequences of Cerebral Microvascular Dysfunction in Aging.

Increasing evidence from epidemiological, clinical and experimental studies indicate that age-related cerebromicrovascular dysfunction and microcirculatory damage play critical roles in the pathogenesis of many types of dementia in the elderly, including Alzheimer's disease. Understanding and targeting the age-related pathophysiological mechanisms that underlie vascular contributions to cognitive impairment and dementia (VCID) is expected to have a major role in preserving brain health in older individuals....

Prediction of Hemodynamics under Left Ventricular Assist Device.

Left ventricular assist device (LVAD) saves lives in patients with severe left ventricular (LV) failure. However, predicting how much LVAD boosts total cardiac output (CO) remains difficult. This study aimed to develop a framework to quantitatively predict the impact of LVAD on hemodynamics. We adopted the circulatory equilibrium framework and incorporated LVAD into the integrated CO curve to derive the circulatory equilibrium. In anesthetized dogs, we ligated left coronary arteries to create LV failure and...

Parental vitamin D deficiency during pregnancy is associated with increased blood pressure in offspring via Panx1 hypermethylation.

Vitamin D deficiency is one of the most common nutritional deficiencies worldwide. Maternal vitamin D deficiency is associated with increased susceptibility to hypertension in offspring but the reasons for this remain unknown. The aim of this study was to determine if parental vitamin D deficiency leads to altered DNA methylation in offspring that may relate to hypertension. Male and female Sprague-Dawley rats were fed a standard or vitamin D depleted diet. After 10 weeks, non-sibling rats were mated. The c...

Estrogen Receptor Antagonism Exacerbates Cardiac Structural and Functional Remodeling in Female Rats.

We have previously demonstrated the cardioprotective effects of ovarian hormones against adverse ventricular remodeling imposed by chronic volume overload. Here, we assess the estrogen receptor dependence of this cardioprotection. Four groups of female rats were studied: sham-operated (SHAM), volume overloaded (ACF), SHAM treated with estrogen receptor antagonist, ICI 182,780 (SHAM+ICI), and ACF treated with ICI. Cardiac function was assessed temporally using echocardiogram and tissue samples were collected...

Exaggerated coronary vasoconstriction limits muscle metaboreflex-induced increases in ventricular performance in hypertension.

Increases in myocardial oxygen consumption during exercise mainly occur via increases in coronary blood flow (CBF) as cardiac oxygen extraction is high even at rest. However, sympathetic coronary constrictor tone can limit increases in CBF. Increased sympathetic nerve activity (SNA) during exercise is, in part, a function of muscle metaboreflex activation (MMA). As SNA is heightened even at rest in subjects with hypertension (HTN), we tested whether HTN causes exaggerated coronary vasoconstriction during mi...

Toll-like receptor 9 prevents cardiac rupture after myocardial infarction in mice independently of inflammation.

We have reported that the Toll-like receptor 9 (TLR9) signaling pathway plays an important role in the development of pressure overload-induced inflammatory responses and heart failure. However, its role in cardiac remodeling after myocardial infarction has not been elucidated.TLR9-deficient and control C57Bl/6 wild-type mice were subjected to left coronary artery ligation. The survival rate 14 days post-operation was significantly lower in TLR9-deficient mice than that in wild-type mice with evidence of ca...

Cardiomyopathy-related mutation (A30V) in mouse cardiac troponin T divergently alters the magnitude of stretch activation in α- and β-myosin heavy chain fibers.

The present study investigated the functional consequences of the human hypertrophic cardiomyopathy (HCM) mutation, A28V, in cardiac troponin T (TnT). The A28V mutation is located within the N-terminus of TnT, a region known to be important for full activation of cardiac thin filaments. The functional consequences of the A28V mutation in TnT remain unknown. Given how α- and β-myosin heavy chain (MHC) isoforms differently alter the effect of the N-terminus of TnT, we hypothesized that the A28V-induced effe...

Left and right ventricular hemodynamic forces in healthy volunteers and elite athletes assessed with 4D flow magnetic resonance imaging.

Intracardiac blood flow is driven by hemodynamic forces that are exchanged between the blood and myocardium. Previous studies have been limited to 2D measurements or investigated only LV forces. Right ventricular forces and their mechanistic contribution to asymmetric redirection of flow in the RV have not been measured. We therefore aimed to quantify three-dimensional hemodynamic forces in both ventricles in a cohort of healthy subjects, using magnetic resonance imaging 4D flow measurements. 25 controls,14...

Role of MicroRNA in Metabolic Shift During Heart Failure.

Heart failure (HF) is an endpoint resulting from a number of disease states. The prognosis for HF patients is poor with survival rates precipitously low. Energy metabolism is centrally linked to the development of HF and it involves the proteomic remodeling of numerous pathways, many of which are targeted to the mitochondrion. MicroRNA (miRNA) are noncoding RNAs that influence post-transcriptional gene regulation. MiRNA have garnered considerable attention for their ability to orchestrate changes to the tra...

Changes in cardiac NaV1.5 expression, function, and acetylation by pan-histone deacetylase inhibitors.

Histone deacetylase (HDAC) inhibitors are small molecule anti-cancer therapeutics that exhibit limiting cardiotoxicities including QT interval prolongation and life-threatening cardiac arrhythmias. Because the molecular mechanisms for HDAC inhibitor-induced cardiotoxicity are poorly understood, we performed whole cell patch voltage clamp experiments to measure cardiac sodium currents (INa) from wild-type neonatal mouse ventricular or human induced pluripotent stem cell derived cardiomyocytes treated with tr...

GLP-1 inhibits VEGFA-mediated signaling in isolated human endothelial cells and VEGFA-induced dilation of rat mesenteric arteries.

We investigated the acute effects of glucagon-like peptides-1 (GLP-1), GLP-1(1-36) and GLP-1(7-36) on vascular endothelial growth factor-A (VEGFA)-induced endothelium-dependent signaling and vasodilation. Our hypothesis was that GLP-1 released from intestinal L-cells modulates processes related to PLCγ activation, Src and eNOS signaling, thereby controlling endothelial vessel tone. By using RT-PCR we found mRNA for the GLP-1 receptor (GLP-1R) in human dermal microvascular endothelial cells (HDMEC), human r...

Resistance-Based Interval Exercise Acutely Improves Endothelial Function In Type 2 Diabetes.

Different modes of exercise, disease and training status can modify endothelial shear stress and result in distinct effects on endothelial function. To date, no study has examined the influence of type 2 diabetes (T2D) and training status on the acute endothelial response to different modes of interval exercise (INT). We examined the effect of a single session of resistance- and cardio-based INT compared to time-matched control on endothelial function in 12 age-matched T2D participants, 12 untrained and 11 ...

Vascular function assessed by passive leg movement and flow-mediated dilation: Initial evidence of construct validity.

The vasodilatory response to passive leg movement (PLM) appears to provide a novel, non-invasive assessment of vascular function. However, PLM has yet to be compared to the established non-invasive assessment of vascular health, flow mediated dilation (FMD). Therefore, as an initial evaluation of the construct validity of PLM, upright seated and supine PLM as well as brachial (BA) and superficial femoral (SFA) artery FMDs were performed in 10 young (22±1) and 30 old (73±2) subjects. During upright seated ...

HYDROGEN SULFIDE CONCENTRATIONS IN THE HEART FOLLOWING ACUTE H2S ADMINISTRATION: METHODOLOGICAL AND PHYSIOLOGICAL CONSIDERATIONS.

In this study, we have tried to characterize the limits of the approach typically used to determine H2S concentrations in the heart based on the amount of H2S evaporating from heart homogenates - spontaneously, after reaction with a strong reducing agent or in a very acidic solution. Heart homogenates were prepared from male rats in control conditions, following H2S infusion induced a transient cardiogenic shock (CS) or cardiac asystole (CA). Using a method of determination of gaseous H2S with a detection l...

Exercise intensity modulates the appearance of circulating microvesicles with pro-angiogenic potential upon endothelial cells.

The effect of endurance exercise on circulating microvesicle dynamics and their impact upon surrounding endothelial cells is unclear. Here we tested the hypothesis that exercise intensity modulates the time-course of platelet (PMV) and endothelial-derived (EMV) microvesicle appearance in the circulation through haemodynamic and biochemical-related mechanisms, and that microvesicles formed during exercise would stimulate endothelial angiogenesis in vitro. Nine healthy young men had venous blood samples taken...

Mitochondrial tRNA mutation with high salt stimulation on cardiac damage: underlying mechanism associated with change of Bax and VDAC.

Mitochondrial transfer RNA (tRNA) mutation with high salt stimulation can cause high blood pressure. However, the underlying mechanisms remain unclear. In the present study, we examined the potential molecular mechanisms of cardiac damage caused by mitochondrial tRNA mutation with high salt stimulation in spontaneously hypertensive rats (SHR). Unanesthetized, 44-wk old, male, SHR were divided into four groups: SHR, SHR with high salt stimulation for 8 wk (SHR+NaCl), SHR carrying tRNA mutations (SHR+M), and ...

Catalase-Dependent H2O2 Consumption by Cardiac Mitochondria and Redox-Mediated Loss in Insulin Signaling.

We have recently demonstrated that catalase content in mouse cardiac mitochondria is selectively elevated in response to high dietary fat, a nutritional state associated with oxidative stress and loss in insulin signaling. Catalase and various isoforms of glutathione peroxidase and peroxiredoxin each catalyze the consumption of H2O2 Catalase, located primarily within peroxisomes and to a lesser extent mitochondria, has a low binding affinity for H2O2 relative to glutathione peroxidase and peroxiredoxin. As ...

Hyperaldosteronism induces left atrial systolic and diastolic dysfunction.

Patients with hypertension and hyperaldosteronism show an increased risk of stroke compared to patients with essential hypertension. Aim of the study was to assess the effects of aldosterone on left atrial function in rats as a potential contributor to thromboembolism. Osmotic mini-pumps delivering 1.5μg aldosterone/h were implanted in rats subcutaneously (Aldo, n=39, controls n=38). After 8 weeks left ventricular pressure- volume analysis of isolated working hearts was performed and left atrial systolic a...

Traumatic brain injury-induced autoregulatory dysfunction and spreading depression-related neurovascular uncoupling: pathomechanism and therapeutic implications.

Traumatic brain injury (TBI) is a major health problem worldwide. In addition to its high mortality (35-40%) survivors are left with cognitive, behavioral and communicative disabilities. While little can be done to reverse initial, primary brain damage caused by trauma, the secondary injury of cerebral tissue due to cerebromicrovascular alterations and dysregulation of cerebral blood flow (CBF) is potentially preventable. This review focuses on functional, cellular and molecular changes of autoregulatory fu...

Interaction Between the Muscle Metaboreflex and the Arterial Baroreflex in Control of Arterial Pressure and Skeletal Muscle Blood Flow.

The muscle metaboreflex and arterial baroreflex regulate arterial pressure through distinct mechanisms. During submaximal exercise muscle metaboreflex activation (MMA) elicits a pressor response virtually solely by increasing cardiac output (CO) while baroreceptor unloading increases mean arterial pressure (MAP) primarily through peripheral vasoconstriction. The interaction between the two reflexes when activated simultaneously has not been well established. We activated the muscle metaboreflex in chronical...

Reduced mitochondrial respiration in the ischemic as well as in the remote non-ischemic region in post-myocardial infarction remodeling.

Scarring and remodeling of the left ventricle (LV) after myocardial infarction (MI) results in ischemic cardiomyopathy with reduced contractile function. Regional differences related to persisting ischemia may exist. We investigated the hypothesis that mitochondrial function and structure is altered in the myocardium adjacent to MI with reduced perfusion (MIadjacent) and less so in the remote, non-ischemic myocardium (MIremote). We used a pig model of chronic coronary stenosis and MI (N=13). Functional and ...

Pulmonary artery smooth muscle cell hyperproliferation and metabolic shift triggered by pulmonary overcirculation.

Vascular cell hyperproliferation and metabolic reprogramming contribute to the pathophysiology of pulmonary arterial hypertension (PAH) in adults. An important cause of PAH in children with congenital heart disease (CHD) is increased pulmonary blood flow (PBF). In order to better characterize this disease course we studied early changes in pulmonary artery smooth muscle cell (PASMC) proliferation and metabolism using a unique ovine model of pulmonary over-circulation. Consistent with PAH in adults, PASMCs d...


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