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https://www.readbyqxmd.com/read/28226461/role-of-cytosolic-calcium-diffusion-in-cardiac-purkinje-cells
#1
Bijay Limbu, Kushal Shah, Makarand Deo, Bijay Limbu, Kushal Shah, Makarand Deo, Bijay Limbu, Makar Deo, Kushal Shah
The Cardiac Purkinje cells (PCs) exhibit distinct calcium (Ca(2)+) homeostasis than that in ventricular myocytes (VMs). Due to lack of t-tubules in PCs, the Ca(2)+ ions entering the cell have to diffuse through the cytoplasm to reach the sarcoplasmic reticulum (SR) before triggering Ca(2)+-induced-Ca(2)+-release (CICR). In recent experimental studies PCs have been shown to be more susceptible to action potential (AP) abnormalities than the VMs, however the exact mechanisms are poorly understood. In this study, we utilize morphologically realistic detailed biophysical mathematical model of a murine PC to systematically examine the role intracellular Ca(2)+ diffusion in the APs of PCs...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
https://www.readbyqxmd.com/read/28226027/serum-25-hydroxyvitamin-d-levels-are-associated-with-functional-capacity-but-not-with-postural-balance-in-osteoporotic-postmenopausal-women
#2
Guilherme Carlos Brech, Emmanuel Gomes Ciolac, Mark D Peterson, Júlia Maria D'Andréa Greve
OBJECTIVES: In post-menopausal women with osteoporosis, insufficient vitamin D levels decrease calcium fixation in the bones and calcium transport in the sarcoplasmic reticulum, which impairs muscle strength, possibly leading to detrimental consequences for the preservation of functional capacity and postural balance, fall prevention, and fracture risk. The aim of this study was to evaluate the association between vitamin D levels and knee muscle strength, postural balance and functional mobility among postmenopausal women with osteoporosis...
January 1, 2017: Clinics
https://www.readbyqxmd.com/read/28222421/luteolin-enhances-sarcoplasmic-reticulum-ca2-atpase-activity-through-p38-mapk-signaling-thus-improving-rat-cardiac-function-after-ischemia-reperfusion
#3
Shasha Zhu, Tongda Xu, Yuanyuan Luo, Yingying Zhang, Haochen Xuan, Yanfeng Ma, Defeng Pan, Dongye Li, Hong Zhu
BACKGROUND/AIMS: A major challenge for current therapeutic strategies against ischemia/reperfusion (I/R) is the lack of effective drugs. Considering luteolin enhances the activity of sarcoplasmic reticulum Ca2+-ATPase (SERCA2a) to improve the systolic/diastolic function of rat hearts and cardiomyocytes during the I/R process, we studied the regulatory function of the p38 MAPK pathway in this protective mechanism. METHODS: Isolated cardiomyocytes and perfused hearts were separately divided into five groups and used to investigate I/R...
February 21, 2017: Cellular Physiology and Biochemistry
https://www.readbyqxmd.com/read/28218221/gene-expressions-underlying-mishandled-calcium-clearance-and-elevated-generation-of-reactive-oxygen-species-in-the-coronary-artery-smooth-muscle-cells-of-chronic-heart-failure-rats
#4
Liang Ding, Xian-Xiu Su, Wen-Hui Zhang, Yu-Xiang Xu, Xue-Feng Pan
BACKGROUND: The calcium clearance and reactive oxygen species (ROS) generations in the coronary artery smooth muscle cells in chronic heart failure (HF) have not been fully investigated. Therefore, we attempted to understand the gene expressions underlying the mishandling of calcium clearance and the accumulations of ROS. METHODS: We initially established an animal model of chronic HF by making the left anterior descending coronary artery ligation (CAL) in rats, and then isolated the coronary artery vascular smooth muscle cells from the ischemic and the nonischemic parts of the coronary artery vessels in 12 weeks after CAL operation...
2017: Chinese Medical Journal
https://www.readbyqxmd.com/read/28214885/signaling-pathway-for-endothelin-1-and-phenylephrine-induced-camp-response-element-binding-protein-activation-in-rat-ventricular-myocytes-role-of-inositol-1-4-5-trisphosphate-receptors-and-camkii
#5
Krishna P Subedi, Min-Jeong Son, Bojjibabu Chidipi, Seong-Woo Kim, Jun Wang, Kyeong-Hee Kim, Sun-Hee Woo, Joon-Chul Kim
BACKGROUND/AIMS: Endothelin-1 (ET-1) and the α<Sub>1</Sub>-adrenoceptor agonist phenylephrine (PE) activate cAMP response element binding protein (CREB), a transcription factor implicated in cardiac hypertrophy. The signaling pathway involved in CREB activation by these hypertrophic stimuli is poorly understood. We examined signaling pathways for ET-1- or PE-induced cardiac CREB activation. METHODS: Western blotting was performed with pharmacological and genetic interventions in rat ventricular myocytes...
January 26, 2017: Cellular Physiology and Biochemistry
https://www.readbyqxmd.com/read/28214269/immunohistochemistry-on-a-panel-of-emery-dreifuss-muscular-dystrophy-samples-reveals-nuclear-envelope-proteins-as-inconsistent-markers-for-pathology
#6
Phu Le Thanh, Peter Meinke, Nadia Korfali, Vlastimil Srsen, Michael I Robson, Manfred Wehnert, Benedikt Schoser, Caroline A Sewry, Eric C Schirmer
Reports of aberrant distribution for some nuclear envelope proteins in cells expressing a few Emery-Dreifuss muscular dystrophy mutations raised the possibility that such protein redistribution could underlie pathology and/or be diagnostic. However, this disorder is linked to 8 different genes encoding nuclear envelope proteins, raising the question of whether a particular protein is most relevant. Therefore, myoblast/fibroblast cultures from biopsy and tissue sections from a panel of nine Emery-Dreifuss muscular dystrophy patients (4 male, 5 female) including those carrying emerin and FHL1 (X-linked) and several lamin A (autosomal dominant) mutations were stained for the proteins linked to the disorder...
December 21, 2016: Neuromuscular Disorders: NMD
https://www.readbyqxmd.com/read/28213332/shear-stress-enhances-ca-2-sparks-through-nox2-dependent-mitochondrial-reactive-oxygen-species-generation-in-rat-ventricular-myocytes
#7
Joon-Chul Kim, Jun Wang, Min-Jeong Son, Sun-Hee Woo
Shear stress enhances diastolic and systolic Ca(2+) concentration in ventricular myocytes. Here, using confocal Ca(2+) imaging in rat ventricular myocytes, we assessed the effects of shear stress (~16dyn/cm(2)) on the frequency of spontaneous Ca(2+) sparks and explored the mechanism underlying shear-mediated Ca(2+) spark regulation. The frequency of Ca(2+) sparks was immediately increased by shear stress (by ~80%), and increased further (by ~150%) during prolonged exposure (20s). The 2-D size and duration of individual sparks were increased by shear stimulation...
February 14, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/28212795/nanojunctions-of-the-sarcoplasmic-reticulum-deliver-site-and-function-specific-calcium-signaling-in-vascular-smooth-muscles
#8
A M Evans
Vasoactive agents may induce myocyte contraction, dilation, and the switch from a contractile to a migratory-proliferative phenotype(s), which requires changes in gene expression. These processes are directed, in part, by Ca(2+) signals, but how different Ca(2+) signals are generated to select each function is enigmatic. We have previously proposed that the strategic positioning of Ca(2+) pumps and release channels at membrane-membrane junctions of the sarcoplasmic reticulum (SR) demarcates cytoplasmic nanodomains, within which site- and function-specific Ca(2+) signals arise...
2017: Advances in Pharmacology
https://www.readbyqxmd.com/read/28209802/doublet-stimulation-increases-ca-2-binding-to-troponin-c-to-ensure-rapid-force-development-in-skeletal-muscle
#9
Anthony J Bakker, Tanya R Cully, Catherine D Wingate, Christopher J Barclay, Bradley S Launikonis
Fast-twitch skeletal muscle fibers are often exposed to motor neuron double discharges (≥200 Hz), which markedly increase both the rate of contraction and the magnitude of the resulting force responses. However, the mechanism responsible for these effects is poorly understood, likely because of technical limitations in previous studies. In this study, we measured cytosolic Ca(2+) during doublet activation using the low-affinity indicator Mag-Fluo-4 at high temporal resolution and modeled the effects of doublet stimulation on sarcoplasmic reticulum (SR) Ca(2+) release, binding of Ca(2+) to cytosolic buffers, and force enhancement in fast-twitch fibers...
February 16, 2017: Journal of General Physiology
https://www.readbyqxmd.com/read/28209766/glycosylated-chromogranin-a-in-heart-failure-implications-for-processing-and-cardiomyocyte-calcium-homeostasis
#10
Anett Hellebø Ottesen, Cathrine R Carlson, William E Louch, Mai Britt Dahl, Ragnhild A Sandbu, Rune Forstrøm Johansen, Hilde Jarstadmarken, Magnar Bjørås, Arne Didrik Høiseth, Jon Brynildsen, Ivar Sjaastad, Mats Stridsberg, Torbjørn Omland, Geir Christensen, Helge Røsjø
BACKGROUND: Chromogranin A (CgA) levels have previously been found to predict mortality in heart failure (HF), but currently no information is available regarding CgA processing in HF and whether the CgA fragment catestatin (CST) may directly influence cardiomyocyte function. METHODS AND RESULTS: CgA processing was characterized in postinfarction HF mice and in patients with acute HF, and the functional role of CST was explored in experimental models. Myocardial biopsies from HF, but not sham-operated mice, demonstrated high molecular weight CgA bands...
February 2017: Circulation. Heart Failure
https://www.readbyqxmd.com/read/28202702/congenital-myopathy-associated-with-the-triadin-knockout-syndrome
#11
Andrew G Engel, Keeley R Redhage, David J Tester, Michael J Ackerman, Duygu Selcen
OBJECTIVE: Triadin is a component of the calcium release complex of cardiac and skeletal muscle. Our objective was to analyze the skeletal muscle phenotype of the triadin knockout syndrome. METHODS: We performed clinical evaluation, analyzed morphologic features by light and electron microscopy, and immunolocalized triadin in skeletal muscle. RESULTS: A 6-year-old boy with lifelong muscle weakness had a triadin knockout syndrome caused by compound heterozygous null mutations in triadin...
February 15, 2017: Neurology
https://www.readbyqxmd.com/read/28195313/neuronal-sodium-channels-emerging-components-of-the-nano-machinery-of-cardiac-calcium-cycling
#12
Rengasayee Veeraraghavan, Sándor Györke, Przemysław B Radwański
Excitation-contraction coupling (ECC) is the bridge between cardiac electrical activation and mechanical contraction. It is driven by the influx of Ca(2+) across the sarcolemma triggering Ca(2+) release from the sarcoplasmic reticulum (SR) - a process termed Ca(2+) -induced Ca(2+) release (CICR) - followed by re-sequestration of Ca(2+) into the SR. The sodium calcium exchanger (NCX) inextricably couples the cycling of Ca(2+) and Na(+) in cardiac myocytes. Thus, influx of Na(+) via voltage-gated Na(+) channels (NaV ) has emerged as an important regulator of CICR both in health and in disease...
February 14, 2017: Journal of Physiology
https://www.readbyqxmd.com/read/28181690/calcium-mediated-cellular-triggered-activity-in-atrial-fibrillation
#13
Dobromir Dobrev, Xander H T Wehrens
Although atrial fibrillation (AF) is the most commonly encountered cardiac arrhythmia, the basic mechanisms underlying this disorder remain incompletely understood. During the past decade or so, it has become clear that alterations in intracellular Ca(2+) handling may play a role in the pathogenesis of AF. Studies in small and large animal models, as well as atrial samples from patients with different forms of AF have implicated ryanodine receptor type 2 (RyR2) dysfunction and enhanced spontaneous Ca(2+) release events from the sarcoplasmic reticulum (SR) as a potential cause of proarrhythmic cellular ectopic (triggered) activity in AF...
February 9, 2017: Journal of Physiology
https://www.readbyqxmd.com/read/28179209/administration-of-anabolic-steroid-during-adolescence-induces-long-term-cardiac-hypertrophy-and-increases-susceptibility-to-ischemia-reperfusion-injury-in-adult-wistar-rats
#14
Fernando de Azevedo Cruz Seara, Raiana Andrade Quintanilha Barbosa, Dahienne Ferreira de Oliveira, Diorney Luiz Souza Gran da Silva, Adriana Bastos Carvalho, Andrea Claudia Freitas Ferreira, José Hamilton Matheus Nascimento, Emerson Lopes Olivares
Chronic administration of anabolic androgenic steroids (AAS) in adult rats results in cardiac hypertrophy and increased susceptibility to myocardial ischemia/reperfusion (IR) injury. Molecular analyses demonstrated that hyperactivation of type 1 angiotensin II (AT1) receptor mediates cardiac hypertrophy induced by AAS and also induces down-regulation of myocardial ATP-sensitive potassium channel (KATP), resulting in loss of exercise-induced cardioprotection. Exposure to AAS during adolescence promoted long-term cardiovascular dysfunctions, such as dysautonomia...
February 5, 2017: Journal of Steroid Biochemistry and Molecular Biology
https://www.readbyqxmd.com/read/28177127/emerging-roles-of-er-stress-and-unfolded-protein-response-pathways-in-skeletal-muscle-health-and-disease
#15
REVIEW
Kyle R Bohnert, Joseph D McMillan, Ashok Kumar
Skeletal muscle is the most abundant tissue in the human body and can adapt its mass as a consequence of physical activity, metabolism, growth factors, and disease conditions. Skeletal muscle contains an extensive network of endoplasmic reticulum (ER), called sarcoplasmic reticulum, which plays an important role in the regulation of proteostasis and calcium homeostasis. In many cell types, environmental and genetic factors that disrupt ER function cause an accumulation of misfolded and unfolded proteins in the ER lumen that ultimately leads to ER stress...
February 8, 2017: Journal of Cellular Physiology
https://www.readbyqxmd.com/read/28176257/left-ventricular-phase-entropy-novel-prognostic-predictor-in-patients-with-dilated-cardiomyopathy-and-narrow-qrs
#16
Naoaki Kano, Takahiro Okumura, Satoshi Isobe, Akinori Sawamura, Naoki Watanabe, Kenji Fukaya, Hiroaki Mori, Ryota Morimoto, Katsuhiko Kato, Yasuko K Bando, Toyoaki Murohara
BACKGROUND: The prognostic impact and pathophysiology of global left ventricular mechanical dyssynchrony (LVMD), namely mechanical dyssynchrony of whole left ventricle, as assessed by phase analysis of electrocardiographically gated (ECG-gated) myocardial perfusion SPECT has not been clearly elucidated in patients with dilated cardiomyopathy (DCM) and narrow QRS complex (<120 ms). METHODS AND RESULTS: Forty-six patients with DCM underwent ECG-gated myocardial (99m)Tc-sestamibi perfusion SPECT and endomyocardial biopsy...
February 7, 2017: Journal of Nuclear Cardiology: Official Publication of the American Society of Nuclear Cardiology
https://www.readbyqxmd.com/read/28174265/sgk3-sustains-er%C3%AE-signaling-and-drives-acquired-aromatase-inhibitor-resistance-through-maintaining-endoplasmic-reticulum-homeostasis
#17
Yuanzhong Wang, Dujin Zhou, Sheryl Phung, Charles Warden, Rumana Rashid, Nymph Chan, Shiuan Chen
Many estrogen receptor alpha (ERα)-positive breast cancers initially respond to aromatase inhibitors (AIs), but eventually acquire resistance. Here, we report that serum- and glucocorticoid-inducible kinase 3 (SGK3), a kinase transcriptionally regulated by ERα in breast cancer, sustains ERα signaling and drives acquired AI resistance. SGK3 is up-regulated and essential for endoplasmic reticulum (EnR) homeostasis through preserving sarcoplasmic/EnR calcium ATPase 2b (SERCA2b) function in AI-resistant cells...
February 7, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28169003/increased-calcium-leak-associated-with-reduced-calsequestrin-expression-in-hyperthyroid-cardiomyocytes
#18
David R de Alba-Aguayo, Natalia Pavón, Martha Mercado-Morales, Miyamin Miranda-Saturnino, Mavil López-Casamichana, Agustin Guerrero-Hernández, Angelica Rueda
INTRODUCTION: Calcium (Ca(2+)) leak during cardiac diastole is chiefly mediated by intracellular Ca(2+) channel/Ryanodine Receptors. Increased diastolic Ca(2+) leak has been proposed as the mechanism underlying the appearance of hereditary arrhythmias. However, little is known about alterations in diastolic Ca(2+) leak and the specific roles played by key intracellular Ca(2+)-handling proteins in hyperthyroidism, a known arrhythmogenic condition. AIM: We sought to determine whether there were modifications in diastolic Ca(2+) leak, based on the recording of Ca(2+) sparks and Ca(2+) waves; we also investigated changes in the expression and activity of key Ca(2+) handling proteins, including ryanodine receptors, Sarco-Endoplasmic Reticulum Ca(2+) ATPase pump and calsequestrin in isolated left-ventricular cardiomyocytes isolated from hyperthyroid rats...
January 23, 2017: Cell Calcium
https://www.readbyqxmd.com/read/28164426/mechanisms-of-charge-transfer-in-human-copper-atpases-atp7a-and-atp7b
#19
REVIEW
Francesco Tadini-Buoninsegni, Serena Smeazzetto
ATP7A and ATP7B are Cu(+) -transporting ATPases of subclass IB and play a fundamental role in intracellular copper homeostasis. ATP7A/B transfer Cu(+) ions across the membrane from delivery to acceptor proteins without establishing a free Cu(+) gradient. Transfer of copper across the membrane is coupled to ATP hydrolysis. Current measurements on solid supported membranes (SSM) were performed to investigate the mechanism of copper-related charge transfer across ATP7A and ATP7B. SSM measurements demonstrated that electrogenic copper displacement occurs within ATP7A/B following addition of ATP and formation of the phosphorylated intermediate...
February 5, 2017: IUBMB Life
https://www.readbyqxmd.com/read/28161542/vasorelaxation-effect-of-glycyrrhizae-uralensis-through-the-endothelium-dependent-pathway
#20
Chu Shan Tan, Yung Sing Ch'ng, Yean Chun Loh, Mohd Zaini Asmawi, Mariam Ahmad, Mun Fei Yam
ETHNOPHARMACOLOGICAL RELEVANCE: Glycyrrhiza uralensis (G. uralensis) is one of the herbs used in traditional Chinese medicine (TCM) and serves as an envoy medicinal. Since G. uralensis plays a major role in the anti-hypertensive TCM formulae, we believe that G. uralensis might possess vasorelaxation activity. AIM OF THE STUDY: This study is designed to investigate the vasorelaxation effect of G. uralensis from various extracts and to study its pharmacology effect...
February 1, 2017: Journal of Ethnopharmacology
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