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Sarcoplasmic reticulum load

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https://www.readbyqxmd.com/read/29030236/long-term-aerobic-exercise-in-calsequestrin2-knockout-mice-accentuates-vagal-antagonism-during-%C3%AE-adrenergic-stimulation-which-restricts-heart-rate-acceleration-and-paradoxically-increases-abnormal-ryanodine-receptor-calcium-leak-in-ventricular-myocytes
#1
Hsiang-Ting Ho, Senthil Thambidorai, Björn C Knollmann, George E Billman, Sandor Györke, Anuradha Kalyanasundaram
BACKGROUND: Long-term aerobic exercise (EX) alters autonomic balance which may not be favorable in heart rate (HR) dependent arrhythmic diseases including Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT) due to preexisting bradycardia and increased sensitivity to parasympathetic stimulation. OBJECTIVE: The purpose of this study was to determine if long-term exercise-induced autonomic adaptations modify CPVT susceptibility. METHODS: We determined exercise-induced parasympathetic effects on HR, arrhythmia incidence and intracellular sarcoplasmic reticulum (SR) Ca(2+) leak in atrial (ACM) and ventricular (VCM) cardiomyocytes, in EX Calsequestrin knockout (CASQ2(-/-)) mice, a model of CPVT...
October 10, 2017: Heart Rhythm: the Official Journal of the Heart Rhythm Society
https://www.readbyqxmd.com/read/29025768/action-potential-shortening-and-impairment-of-cardiac-function-by-ablation-of-slc26a6
#2
Padmini Sirish, Hannah A Ledford, Valeriy Timofeyev, Phung N Thai, Lu Ren, Hyo Jeong Kim, Seojin Park, Jeong Han Lee, Gu Dai, Maryam Moshref, Choong-Ryoul Sihn, Wei Chun Chen, Maria Valeryevna Timofeyeva, Zhong Jian, Rafael Shimkunas, Leighton T Izu, Nipavan Chiamvimonvat, Ye Chen-Izu, Ebenezer N Yamoah, Xiao-Dong Zhang
BACKGROUND: Intracellular pH (pHi) is critical to cardiac excitation and contraction; uncompensated changes in pHi impair cardiac function and trigger arrhythmia. Several ion transporters participate in cardiac pHi regulation. Our previous studies identified several isoforms of a solute carrier Slc26a6 to be highly expressed in cardiomyocytes. We show that Slc26a6 mediates electrogenic Cl(-)/HCO3(-) exchange activities in cardiomyocytes, suggesting the potential role of Slc26a6 in regulation of not only pHi, but also cardiac excitability...
October 2017: Circulation. Arrhythmia and Electrophysiology
https://www.readbyqxmd.com/read/29016724/triggered-intracellular-calcium-waves-in-dog-and-human-left-atrial-myocytes-from-normal-and-failing-hearts
#3
Gary L Aistrup, Rishi Arora, Søren Grubb, Shin Yoo, Benjamin Toren, Manvinder Kumar, Aaron Kunamalla, William Marszalec, Tej Motiwala, Shannon Tai, Sean Yamakawa, Satya Yerrabolu, Francisco J Alvarado, Hector H Valdivia, Jonathan M Cordeiro, Yohannes Shiferaw, J Andrew Wasserstrom
Aims: Abnormal intracellular Ca 2+ cycling contributes to triggered activity and arrhythmias in the heart. We investigated the properties and underlying mechanisms for systolic triggered Ca 2+ waves in left atria from normal and failing dog hearts. Methods and Results: Intracellular Ca 2+ cycling was studied using confocal microscopy during rapid pacing of atrial myocytes (36 °C) isolated from normal and failing canine hearts (ventricular tachypacing model). In normal atrial myocytes (NAMs), Ca 2+ waves developed during rapid pacing at rates ≥ 3...
August 29, 2017: Cardiovascular Research
https://www.readbyqxmd.com/read/28966144/effects-of-exercise-training-on-excitation-contraction-coupling-calcium-dynamics-and-protein-expression-in-the-heart-of-the-neotropical-fish-brycon-amazonicus
#4
Rafael Zanelli Rissoli, Eliton da Silva Vasconcelos, Francisco Tadeu Rantin, Ana Lúcia Kalinin
Matrinxã (Brycon amazonicus) is a great swimming performance teleost fish from the Amazon basin. However, the possible cardiac adaptations of this ability are still unknown. Therefore, the aim of the present work was to investigate the effects of prolonged exercise (EX group - 60days under 0.4BL·s(-1)) on ventricular contractility by (i) in-vitro analysis of contractility comparing the relative roles of sodium/calcium exchanger (NCX) and sarcoplasmic reticulum (SR) in the excitation-contraction (E-C) coupling and (ii) molecular analysis of NCX, sarcoplasmic reticulum Ca(2+) ATPase (SERCA2) and phospholamban (PLB) expression and quantification...
September 29, 2017: Comparative Biochemistry and Physiology. Part A, Molecular & Integrative Physiology
https://www.readbyqxmd.com/read/28964152/minimal-model-for-calcium-alternans-due-to-sr-release-refractoriness
#5
Inma R Cantalapiedra, Enrique Alvarez-Lacalle, Angelina Peñaranda, Blas Echebarria
In the heart, rapid pacing rates may induce alternations in the strength of cardiac contraction, termed pulsus alternans. Often, this is due to an instability in the dynamics of the intracellular calcium concentration, whose transients become larger and smaller at consecutive beats. This alternation has been linked experimentally and theoretically to two different mechanisms: an instability due to (1) a strong dependence of calcium release on sarcoplasmic reticulum (SR) load, together with a slow calcium reuptake into the SR or (2) to SR release refractoriness, due to a slow recovery of the ryanodine receptors (RyR2) from inactivation...
September 2017: Chaos
https://www.readbyqxmd.com/read/28793220/mechanism-for-triggered-waves-in-atrial-myocytes
#6
Yohannes Shiferaw, Gary L Aistrup, J Andrew Wasserstrom
Excitation-contraction coupling in atrial cells is mediated by calcium (Ca) signaling between L-type Ca channels and Ryanodine receptors that occurs mainly at the cell boundary. This unique architecture dictates essential aspects of Ca signaling under both normal and diseased conditions. In this study we apply laser scanning confocal microscopy, along with an experimentally based computational model, to understand the Ca cycling dynamics of an atrial cell subjected to rapid pacing. Our main finding is that when an atrial cell is paced under Ca overload conditions, Ca waves can then nucleate on the cell boundary and propagate to the cell interior...
August 8, 2017: Biophysical Journal
https://www.readbyqxmd.com/read/28752958/increased-ca-buffering-underpins-remodelling-of-ca-2-handling-in-old-sheep-atrial-myocytes
#7
Jessica D Clarke, Jessica L Caldwell, Charles M Pearman, David A Eisner, Andrew W Trafford, Katharine M Dibb
KEY POINTS: Ageing is associated with an increased risk of cardiovascular disease and arrhythmias, with the most common arrhythmia being found in the atria of the heart. Little is known about how the normal atria of the heart remodel with age and thus why dysfunction might occur. We report alterations to the atrial systolic Ca(2+) transient that have implications for the function of the atrial in the elderly. We describe a novel mechanism by which increased Ca buffering can account for changes to systolic Ca(2+) in the old atria...
October 1, 2017: Journal of Physiology
https://www.readbyqxmd.com/read/28648626/mechanosensitivity-of-microdomain-calcium-signalling-in-the-heart
#8
REVIEW
Patrick Schönleitner, Uli Schotten, Gudrun Antoons
In cardiac myocytes, calcium (Ca(2+)) signalling is tightly controlled in dedicated microdomains. At the dyad, i.e. the narrow cleft between t-tubules and junctional sarcoplasmic reticulum (SR), many signalling pathways combine to control Ca(2+)-induced Ca(2+) release during contraction. Local Ca(2+) gradients also exist in regions where SR and mitochondria are in close contact to regulate energetic demands. Loss of microdomain structures, or dysregulation of local Ca(2+) fluxes in cardiac disease, is often associated with oxidative stress, contractile dysfunction and arrhythmias...
June 23, 2017: Progress in Biophysics and Molecular Biology
https://www.readbyqxmd.com/read/28630914/deregulated-ca-2-cycling-underlies-the-development-of-arrhythmia-and-heart-disease-due-to-mutant-obscurin
#9
Li-Yen R Hu, Maegen A Ackermann, Peter A Hecker, Benjamin L Prosser, Brendan King, Kelly A O'Connell, Alyssa Grogan, Logan C Meyer, Christopher E Berndsen, Nathan T Wright, W Jonathan Lederer, Aikaterini Kontrogianni-Konstantopoulos
Obscurins are cytoskeletal proteins with structural and regulatory roles encoded by OBSCN. Mutations in OBSCN are associated with the development of hypertrophic cardiomyopathy (HCM) and dilated cardiomyopathy (DCM). Specifically, the R4344Q mutation present in immunoglobulin domain 58 (Ig58) was the first to be linked with the development of HCM. To assess the effects of R4344Q in vivo, we generated the respective knock-in mouse model. Mutant obscurins are expressed and incorporated normally into sarcomeres...
June 2017: Science Advances
https://www.readbyqxmd.com/read/28592415/role-of-stim1-stromal-interaction-molecule-1-in-hypertrophy-related-contractile-dysfunction
#10
Constantine D Troupes, Markus Wallner, Giulia Borghetti, Chen Zhang, Sadia Mohsin, Dirk von Lewinski, Remus M Berretta, Hajime Kubo, Xiongwen Chen, Jonathan Soboloff, Steven Houser
RATIONALE: Pathological increases in cardiac afterload result in myocyte hypertrophy with changes in myocyte electrical and mechanical phenotype. Remodeling of contractile and signaling Ca(2+) occurs in pathological hypertrophy and is central to myocyte remodeling. STIM1 (stromal interaction molecule 1) regulates Ca(2+) signaling in many cell types by sensing low endoplasmic reticular Ca(2+) levels and then coupling to plasma membrane Orai channels to induce a Ca(2+) influx pathway. Previous reports suggest that STIM1 may play a role in cardiac hypertrophy, but its role in electrical and mechanical phenotypic alterations is not well understood...
July 7, 2017: Circulation Research
https://www.readbyqxmd.com/read/28550171/%C3%AE-adrenergic-receptor-stimulation-inhibits-proarrhythmic-alternans-in-postinfarction-border-zone-cardiomyocytes-a-computational-analysis
#11
Jakub Tomek, Blanca Rodriguez, Gil Bub, Jordi Heijman
The border zone (BZ) of the viable myocardium adjacent to an infarct undergoes extensive autonomic and electrical remodeling and is prone to repolarization alternans-induced cardiac arrhythmias. BZ remodeling processes may promote or inhibit Ca(2+) and/or repolarization alternans and may differentially affect ventricular arrhythmogenesis. Here, we used a detailed computational model of the canine ventricular cardiomyocyte to study the determinants of alternans in the BZ and their regulation by β-adrenergic receptor (β-AR) stimulation...
August 1, 2017: American Journal of Physiology. Heart and Circulatory Physiology
https://www.readbyqxmd.com/read/28494965/multiscale-determinants-of-delayed-afterdepolarization-amplitude-in-cardiac-tissue
#12
Christopher Y Ko, Michael B Liu, Zhen Song, Zhilin Qu, James N Weiss
Spontaneous calcium (Ca) waves in cardiac myocytes underlie delayed afterdepolarizations (DADs) that trigger cardiac arrhythmias. How these subcellular/cellular events overcome source-sink factors in cardiac tissue to generate DADs of sufficient amplitude to trigger action potentials is not fully understood. Here, we evaluate quantitatively how factors at the subcellular scale (number of Ca wave initiation sites), cellular scale (sarcoplasmic reticulum (SR) Ca load), and tissue scale (synchrony of Ca release in populations of myocytes) determine DAD features in cardiac tissue using a combined experimental and computational modeling approach...
May 9, 2017: Biophysical Journal
https://www.readbyqxmd.com/read/28439258/diabetic-cardiomyopathy-an-immunometabolic-perspective
#13
REVIEW
Paras K Mishra, Wei Ying, Shyam Sundar Nandi, Gautam K Bandyopadhyay, Kaushik K Patel, Sushil K Mahata
The heart possesses a remarkable inherent capability to adapt itself to a wide array of genetic and extrinsic factors to maintain contractile function. Failure to sustain its compensatory responses results in cardiac dysfunction, leading to cardiomyopathy. Diabetic cardiomyopathy (DCM) is characterized by left ventricular hypertrophy and reduced diastolic function, with or without concurrent systolic dysfunction in the absence of hypertension and coronary artery disease. Changes in substrate metabolism, oxidative stress, endoplasmic reticulum stress, formation of extracellular matrix proteins, and advanced glycation end products constitute the early stage in DCM...
2017: Frontiers in Endocrinology
https://www.readbyqxmd.com/read/28438761/improved-skeletal-muscle-ca-2-regulation-in-vivo-following-contractions-in-mice-overexpressing-pgc-1%C3%AE
#14
Hiroaki Eshima, Shinji Miura, Nanami Senoo, Koji Hatakeyama, David C Poole, Yutaka Kano
In skeletal muscle, resting intracellular Ca(2+) concentration ([Ca(2+)]i) homeostasis is exquisitely regulated by Ca(2+) transport across the sarcolemmal, mitochondrial, and sarcoplasmic reticulum (SR) membranes. Of these three systems, the relative importance of the mitochondria in [Ca(2+)]i regulation remains poorly understood in in vivo skeletal muscle. We tested the hypothesis that the capacity for Ca(2+) uptake by mitochondria is a primary factor in determining [Ca(2+)]i regulation in muscle at rest and following contractions...
June 1, 2017: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
https://www.readbyqxmd.com/read/28424631/mechanisms-underlying-the-emergence-of-post-acidosis-arrhythmia-at-the-tissue-level-a-theoretical-study
#15
Jieyun Bai, Renli Yin, Kuanquan Wang, Henggui Zhang
Acidosis has complex electrophysiological effects, which are associated with a high recurrence of ventricular arrhythmias. Through multi-scale cardiac computer modeling, this study investigated the mechanisms underlying the emergence of post-acidosis arrhythmia at the tissue level. In simulations, ten Tusscher-Panfilov ventricular model was modified to incorporate various data on acidosis-induced alterations of cellular electrophysiology and intercellular electrical coupling. The single cell models were incorporated into multicellular one-dimensional (1D) fiber and 2D sheet tissue models...
2017: Frontiers in Physiology
https://www.readbyqxmd.com/read/28410273/up-regulation-of-intracellular-calcium-handling-underlies-the-recovery-of-endotoxemic-cardiomyopathy-in-mice
#16
Justin C Morse, Joanne Huang, Natasha Khona, Edward J Miller, Deborah A Siwik, Wilson S Colucci, Ion A Hobai
BACKGROUND: In surviving patients, sepsis-induced cardiomyopathy is spontaneously reversible. In the absence of any experimental data, it is generally thought that cardiac recovery in sepsis simply follows the remission of systemic inflammation. Here the authors aimed to identify the myocardial mechanisms underlying cardiac recovery in endotoxemic mice. METHODS: Male C57BL/6 mice were challenged with lipopolysaccharide (7 μg/g, intraperitoneally) and followed for 12 days...
June 2017: Anesthesiology
https://www.readbyqxmd.com/read/28324061/progesterone-protects-against-bisphenol-a-induced-arrhythmias-in-female-rat-cardiac-myocytes-via-rapid-signaling
#17
Jianyong Ma, Kui Hong, Hong-Sheng Wang
Bisphenol A (BPA) is an estrogenic endocrine-disrupting chemical (EDC) that has a range of potential adverse health effects. Previously we showed that acute exposure to BPA promoted arrhythmias in female rat hearts through estrogen receptor rapid signaling. Progesterone (P4) and estrogen have antagonistic or complementary actions in a number of tissues and systems. In the current study, we examined the influence and possible protective effect of P4 on the rapid cardiac actions of BPA in female rat cardiac myocytes...
April 1, 2017: Endocrinology
https://www.readbyqxmd.com/read/28321411/different-densities-of-na-ca-exchange-current-in-t-tubular-and-surface-membranes-and-their-impact-on-cellular-activity-in-a-model-of-rat-ventricular-cardiomyocyte
#18
M Pásek, J Šimurda, G Christé
The ratio of densities of Na-Ca exchanger current (INaCa) in the t-tubular and surface membranes (INaCa-ratio) computed from the values of INaCa and membrane capacitances (Cm) measured in adult rat ventricular cardiomyocytes before and after detubulation ranges between 1.7 and 25 (potentially even 40). Variations of action potential waveform and of calcium turnover within this span of the INaCa-ratio were simulated employing previously developed model of rat ventricular cell incorporating separate description of ion transport systems in the t-tubular and surface membranes...
2017: BioMed Research International
https://www.readbyqxmd.com/read/28292875/in-vivo-ca-2-dynamics-induced-by-ca-2-injection-in-individual-rat-skeletal-muscle-fibers
#19
Mario Wakizaka, Hiroaki Eshima, Yoshinori Tanaka, Hideki Shirakawa, David C Poole, Yutaka Kano
In contrast to cardiomyocytes, store overload-induced calcium ion (Ca(2+)) release (SOICR) is not considered to constitute a primary Ca(2+) releasing system from the sarcoplasmic reticulum (SR) in skeletal muscle myocytes. In the latter, voltage-induced Ca(2+) release (VICR) is regarded as the dominant mechanism facilitating contractions. Any role of the SOICR in the regulation of cytoplasmic Ca(2+) concentration ([Ca(2+)]i) and its dynamics in skeletal muscle in vivo remains poorly understood. By means of in vivo single fiber Ca(2+) microinjections combined with bioimaging techniques, we tested the hypothesis that the [Ca(2+)]i dynamics following Ca(2+) injection would be amplified and fiber contraction facilitated by SOICR...
March 2017: Physiological Reports
https://www.readbyqxmd.com/read/28257761/membrane-potential-determines-calcium-alternans-through-modulation-of-sr-ca-2-load-and-l-type-ca-2-current
#20
Giedrius Kanaporis, Lothar A Blatter
Alternans is a risk factor for cardiac arrhythmia, including atrial fibrillation. At the cellular level alternans is observed as beat-to-beat alternations in contraction, action potential (AP) morphology and magnitude of the Ca(2+) transient (CaT). It is widely accepted that the bi-directional interplay between membrane voltage and Ca(2+) is crucial for the development of alternans, however recently the attention has shifted to instabilities in cellular Ca(2+) handling, while the role of AP alternation remains poorly understood...
April 2017: Journal of Molecular and Cellular Cardiology
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