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Heart muscle contraction

Christine Mohn, Olav Vassend, Stein Knardahl
Background and purpose Psychophysiological factors may contribute to the development of temporomandibular disorders (TMD). Both local orofacial and systemic responses have been investigated. However, most studies have concentrated on physiological responding during cognitive challenges, while responses during painful tasks may be highly relevant for the development of chronic pain conditions. Moreover, the relationship between experimental challenges and physiological responding may be influenced by affective responses during the experimental tasks, an issue not often considered in the literature...
December 29, 2017: Scandinavian Journal of Pain
Kosuke Otani, Mai Yokoya, Tomoko Kodama, Kiko Hori, Kengo Matsumoto, Muneyoshi Okada, Hideyuki Yamawaki
Exosomes, the smallest extracellular vesicle, contain various molecules and mediate cell-cell communication. A number of studies demonstrate exosomes are involved in important physiological and pathological processes. Moreover, microRNA (miRNA) regulating hypertension development through the suppression of certain translation was recently reported. However, roles of exosomes containing various molecules including miRNA on development of essential hypertension have not been examined. We tested the hypothesis that plasma exosomes regulate systemic blood pressure in normotensive and spontaneously hypertensive rats (SHR)...
June 15, 2018: Biochemical and Biophysical Research Communications
Marcin Kunecki, Tomasz Roleder, Jolanta Biernat, Paweł Kukla, Lidia Tomkiewicz-Pająk, Marek A Deja, Piotr Podolec, Krzysztof S Gołba, Wojciech Płazak
BACKGROUND: Opioidergic conditioning is well documented to trigger cardioprotection against ischemia/ reperfusion (I/R) injury. Previous studies on animal models have suggested that nitric oxide (NO) mediates the beneficial effect of opioids, but the role of NO in humans seems to be controversial. OBJECTIVES: The aim of the study was to assess the influence of NO modulators on opioid-induced cardioprotection in the human myocardium. MATERIAL AND METHODS: Trabeculae of the human right atria were electrically driven in an organ bath and subjected to simulated I/R injury...
June 18, 2018: Advances in Clinical and Experimental Medicine: Official Organ Wroclaw Medical University
Yusuf Olgar, Sinan Degirmenci, Aysegul Durak, Deniz Billur, Belgin Can, Gizem Kayki Mutlu, Ebru Arioglu Inan, Belma Turan
Aging in humans represents declining in cardio-protective systems, however its mechanisms are not known yet. We aimed to analyse how aging affects key mechanisms responsible for contractile dysfunction via comparing the improperly synchrony between electrical and mechanical activities in male aged-rats (24-month old) comparison to those of adult-rats (6-month old). We determined significantly increased systemic oxidative stress with decreased antioxidant capacity, clear insulin resistance and hypertrophy in aged-rats with normal fasting blood glucose...
June 13, 2018: Experimental Gerontology
Augusto C Montezano, Livia De Lucca Camargo, Patrik Persson, Francisco J Rios, Adam P Harvey, Aikaterini Anagnostopoulou, Roberto Palacios, Ana Caroline P Gandara, Rheure Alves-Lopes, Karla B Neves, Maria Dulak-Lis, Chet E Holterman, Pedro Lagerblad de Oliveira, Delyth Graham, Christopher Kennedy, Rhian M Touyz
BACKGROUND: NADPH Oxidase 5 (Nox5) is a calcium-sensitive superoxide-generating Nox. It is present in lower forms and higher mammals, but not in rodents. Nox5 is expressed in vascular cells, but the functional significance remains elusive. Given that contraction is controlled by calcium and reactive oxygen species, both associated with Nox5, we questioned the role of Nox5 in pro-contractile signaling and vascular function. METHODS AND RESULTS: Transgenic mice expressing human Nox5 in a vascular smooth muscle cell-specific manner (Nox5 mice) and Rhodnius prolixus , an arthropod model that expresses Nox5 endogenoulsy, were studied...
June 15, 2018: Journal of the American Heart Association
Lorna J Daniels, Rachel S Wallace, Olivia M Nicholson, Genevieve A Wilson, Fiona J McDonald, Peter P Jones, J Chris Baldi, Regis R Lamberts, Jeffrey R Erickson
BACKGROUND: Calcium/calmodulin-dependent kinase II-delta (CaMKIIδ) activity is enhanced during hyperglycemia and has been shown to alter intracellular calcium handling in cardiomyocytes, ultimately leading to reduced cardiac performance. However, the effects of CaMKIIδ on cardiac contractility during type 2 diabetes are undefined. METHODS: We examined the expression and activation of CaMKIIδ in right atrial appendages from non-diabetic and type 2 diabetic patients (n = 7 patients per group) with preserved ejection fraction, and also in right ventricular tissue from Zucker Diabetic Fatty rats (ZDF) (n = 5-10 animals per group) during early diabetic cardiac dysfunction, using immunoblot...
June 14, 2018: Cardiovascular Diabetology
Vincent W W van Eif, Harsha D Devalla, Gerard J J Boink, Vincent M Christoffels
The rate and rhythm of heart muscle contractions are coordinated by the cardiac conduction system (CCS), a generic term for a collection of different specialized muscular tissues within the heart. The CCS components initiate the electrical impulse at the sinoatrial node, propagate it from atria to ventricles via the atrioventricular node and bundle branches, and distribute it to the ventricular muscle mass via the Purkinje fibre network. The CCS thereby controls the rate and rhythm of alternating contractions of the atria and ventricles...
June 6, 2018: Nature Reviews. Cardiology
Terumasa Takahara, Hidetaka Yamaguchi, Kazutoshi Seki, Megumi Murata, Sho Onodera
PURPOSE: The purpose of this study was to clarify the effect one-sided skeletal muscle contraction has on the circulatory system, spinal α-motoneuron excitability, and somatosensory-system-evoked potential. METHOD: Nine healthy males maintained tension at 10, 20, and 30% of maximal voluntary contraction in static gripping in right hand. Heart rate, ln high frequency (HF), blood pressure (BP), F-wave, and somatosensory-evoked potential (SEP) were recorded during gripping task...
June 5, 2018: European Journal of Applied Physiology
Owen Jeffries, Mark Waldron, John R Pattison, Stephen D Patterson
Ischemic preconditioning (IPC), which involves intermittent periods of ischemia followed by reperfusion, is an effective clinical intervention that reduces the risk of myocardial injury and confers ischemic tolerance to skeletal muscle. Repeated bouts of IPC have been shown to stimulate long-term changes vascular function, however, it is unclear what metabolic adaptations may occur locally in the muscle. Therefore, we investigated 7 days of bilateral lower limb IPC (4 × 5 min) above limb occlusion pressure (220 mmHg; n = 10), or sham (20 mmHg; n = 10), on local muscle oxidative capacity and microvascular blood flow...
2018: Frontiers in Physiology
Chao Liu, Masataka Kawana, Dan Song, Kathleen M Ruppel, James A Spudich
Concepts in molecular tension sensing in biology are growing and have their origins in studies of muscle contraction. In the heart muscle, a key parameter of contractility is the detachment rate of myosin from actin, which determines the time that myosin is bound to actin in a force-producing state and, importantly, depends on the load (force) against which myosin works. Here we measure the detachment rate of single molecules of human β-cardiac myosin and its load dependence. We find that both can be modulated by both small-molecule compounds and cardiomyopathy-causing mutations...
June 2018: Nature Structural & Molecular Biology
Roger Charles Young
The laboring uterus is generally thought to initiate contractions much similar to the heart, with a single, dedicated pacemaker. Research on human and animal models over decades has failed to identify such pacemaker. On the contrary, data indicate that instead of being fixed at a site similar to the sinoatrial node of the heart, the initiation site for each uterine contraction changes during time, often with each contraction. The enigmatic uterine "pacemaker" does not seem to fit the standard definition of what a pacemaker should be...
April 26, 2018: Best Practice & Research. Clinical Obstetrics & Gynaecology
Tyler L Marler, Andrew B Wright, Kristina L Elmslie, Ankeeta K Heier, Ethan Remily, Jeong Sook Kim-Han, Renuka Ramachandra, Keith S Elmslie
The exercise pressor reflex (EPR) is activated by muscle contractions to increase heart rate and blood pressure during exercise. While this reflex is beneficial in healthy individuals, the reflex activity is exaggerated in patients with cardiovascular disease, which is associated with increased mortality. Group III and IV afferents mediate the EPR and have been shown to express both tetrodotoxin-sensitive (TTX-S, NaV 1.6, NaV 1.7) and -resistant (TTX-R, NaV 1.8, NaV 1.9) voltage-gated sodium (NaV ) channels, but NaV 1...
May 30, 2018: Journal of Neurophysiology
Amreen Mughal, Stephen T O'Rourke
Apelin is a vasoactive peptide and is an endogenous ligand for APJ receptors, which are widely expressed in blood vessels, heart, and cardiovascular regulatory regions of the brain. A growing body of evidence now demonstrates a regulatory role for the apelin/APJ receptor system in cardiovascular physiology and pathophysiology, thus making it a potential target for cardiovascular drug discovery and development. Indeed, ongoing studies are investigating the potential benefits of apelin and apelin-mimetics for disorders such as heart failure and pulmonary arterial hypertension...
May 25, 2018: Pharmacology & Therapeutics
Tomasz Jazwiec, Marcin Malinowski, Alastair G Proudfoot, Lenora Eberhart, David Langholz, Hans Schubert, Jeremy Wodarek, Tomasz A Timek
OBJECTIVES: Clinical and experimental tricuspid valve physiology data are derived predominantly from anesthetized subjects, but normal tricuspid valve geometry and dynamics may be altered by general anesthesia and mechanical ventilation. We set out to investigate 3-dimensional geometry and dynamics of the tricuspid valve complex in awake and anesthetized sheep. METHODS: While on cardiopulmonary bypass and with the heart beating, 6 adult sheep (50 ± 8 kg) underwent implantation of 6 sonomicrometry crystals around the tricuspid annulus...
April 21, 2018: Journal of Thoracic and Cardiovascular Surgery
Kamonwan Tangvoraphonkchai, Andrew Davenport
Magnesium is the most abundant intracellular divalent cation and essential for maintaining normal cellular physiology and metabolism, acting as a cofactor of numerous enzymes, regulating ion channels and energy generation. In the heart, magnesium plays a key role in modulating neuronal excitation, intracardiac conduction, and myocardial contraction by regulating a number of ion transporters, including potassium and calcium channels. Magnesium also has a role in regulating vascular tone, atherogenesis and thrombosis, vascular calcification, and proliferation and migration of endothelial and vascular smooth muscle cells...
May 2018: Advances in Chronic Kidney Disease
Jan Lubawy, Paweł Marciniak, Mariola Kuczer, Grzegorz Rosiński
Neuropeptides control the functioning of the nervous system of insects, and they are the most diverse signalling molecules in terms of structure and function. Allatostatins are pleiotropic neuropeptides that are considered potent myoinhibitors of muscle contractions in insects. We investigated the effects caused by three distinct allatostatins, Dippu-AST1 (LYDFGL-NH2 from Diploptera punctata), Grybi-MIP1 (GWQDLNGGW-NH2 from Gryllus bimaculatus) and Trica-ASTC (pESRYRQCYFNPISCF-OH from Tribolium castaneum) on contractile activity of the myocardium, oviduct and hindgut of two tenebrionid beetles, Tenebrio molitor and Zophobas atratus...
May 9, 2018: Neuropeptides
Amanda Denniss, Angela F Dulhunty, Nicole A Beard
Calcium release from internal stores is a quintessential event in excitation-contraction coupling in cardiac and skeletal muscle. The ryanodine receptor Ca2+ release channel is embedded in the internal sarcoplasmic reticulum Ca2+ store, which releases Ca2+ into the cytoplasm, enabling contraction. Ryanodine receptors form the hub of a macromolecular complex extending from the extracellular space to the sarcoplasmic reticulum lumen. Ryanodine receptor activity is influenced by the integrated effects of associated co-proteins, ions, and post-translational phosphor and redox modifications...
May 15, 2018: International Journal of Biochemistry & Cell Biology
Yuzhi Jia, Ning Liu, Navin Viswakarma, Ruya Sun, Mathew J Schipma, Meng Shang, Edward B Thorp, Yashpal S Kanwar, Bayar Thimmapaya, Janardan K Reddy
PIMT/NCOA6IP, a transcriptional coactivator PRIP/NCOA6 binding protein, enhances nuclear receptor transcriptional activity. Germline disruption of PIMT results in early embryonic lethality due to impairment of development around blastocyst and uterine implantation stages. We now generated mice with Cre-mediated cardiac-specific deletion of PIMT (csPIMT-/- ) in adult mice. These mice manifest enlargement of heart, with nearly 100% mortality by 7.5 months of age due to dilated cardiomyopathy. Significant reductions in the expression of genes (i) pertaining to mitochondrial respiratory chain complexes I to IV; (ii) calcium cycling cardiac muscle contraction ( Atp2a1 , Atp2a2 , Ryr2 ); and (iii) nuclear receptor PPAR- regulated genes involved in glucose and fatty acid energy metabolism were found in csPIMT-/- mouse heart...
May 16, 2018: International Journal of Molecular Sciences
Gonzalo Del Monte-Nieto, Mirana Ramialison, Arne A S Adam, Bingruo Wu, Alla Aharonov, Gabriele D'Uva, Lauren M Bourke, Mara E Pitulescu, Hanying Chen, José Luis de la Pompa, Weinian Shou, Ralf H Adams, Sarah K Harten, Eldad Tzahor, Bin Zhou, Richard P Harvey
In vertebrate hearts, the ventricular trabecular myocardium develops as a sponge-like network of cardiomyocytes that is critical for contraction and conduction, ventricular septation, papillary muscle formation and wall thickening through the process of compaction 1 . Defective trabeculation leads to embryonic lethality2-4 or non-compaction cardiomyopathy (NCC) 5 . There are divergent views on when and how trabeculation is initiated in different species. In zebrafish, trabecular cardiomyocytes extrude from compact myocardium 6 , whereas in chicks, chamber wall thickening occurs before overt trabeculation 7 ...
May 9, 2018: Nature
Peter Bartels, Dejie Yu, Hua Huang, Zhenyu Hu, Stefan Herzig, Tuck Wah Soong
The CaV 1.2 L-type calcium channel is a key conduit for Ca2+ influx to initiate excitation-contraction coupling for contraction of the heart and vasoconstriction of the arteries and for altering membrane excitability in neurons. Its α1C pore-forming subunit is known to undergo extensive alternative splicing to produce many CaV 1.2 isoforms that differ in their electrophysiological and pharmacological properties. Here, we examined the structure-function relationship of human CaV 1.2 with respect to the inclusion or exclusion of mutually exclusive exons of the N-terminus exons 1/1a and IS6 segment exons 8/8a...
May 8, 2018: Biophysical Journal
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