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Zsolt Mártonfalvi, Pasquale Bianco, Katalin Naftz, György G Ferenczy, Miklós Kellermayer
Titin is a giant protein that provides elasticity to muscle. As the sarcomere is stretched, titin extends hierarchically according to the mechanics of its segments. Whether titin's globular domains unfold during this process and how such unfolded domains might contribute to muscle contractility are strongly debated. To explore the force-dependent folding mechanisms, here we manipulated skeletal-muscle titin molecules with high-resolution optical tweezers. In force-clamp mode, after quenching the force (<10 pN), extension fluctuated without resolvable discrete events...
January 18, 2017: Protein Science: a Publication of the Protein Society
Regula Furrer, Petra S Eisele, Alexander Schmidt, Markus Beer, Christoph Handschin
Activation of resident and infiltrating immune cells is a central event in training adaptation and other contexts of skeletal muscle repair and regeneration. A precise orchestration of inflammatory events in muscle fibers and immune cells is required after recurrent contraction-relaxation cycles. However, the mechanistic aspects of this important regulation remain largely unknown. We now demonstrate that besides a dominant role in controlling cellular metabolism, the peroxisome proliferator-activated receptor γ co-activator 1α (PGC-1α) also has a profound effect on cytokine expression in muscle tissue...
January 16, 2017: Scientific Reports
Eileen S Rodriguez-Tapia, Vinogran Naidoo, Matthew DeVries, Alberto Perez-Medina, James J Galligan
There is evidence that R-type Ca(2+) channels contribute to synaptic transmission in the myenteric plexus. It is unknown if R-type Ca(2+) channels contribute to neuromuscular transmission. We measured the effects of the nitric oxide synthase (NOS) inhibitor, nitro L-arginine (NLA), Ca(2+) channel blockers and apamin (SK channel blocker) on neurogenic relaxations and contractions of the guinea pig ileum longitudinal muscle-myenteric plexus (LMMP) in vitro. We used intracellular recordings to measure inhibitory junction potentials (IJPs)...
December 23, 2016: Experimental Physiology
Andrea Sorrentino, Giulia Borghetti, Yu Zhou, Antonio Cannata, Marianna Meo, Sergio Signore, Piero Anversa, Annarosa Leri, Polina Goichberg, Khaled Qanud, Jason T Jacobson, Thomas H Hintze, Marcello Rota
: Diabetes and other metabolic conditions characterized by elevated blood glucose constitute important risk factors for cardiovascular disease. Hyperglycemia targets myocardial cells rendering ineffective mechanical properties of the heart, but cellular alterations dictating the progressive deterioration of cardiac function with metabolic disorders remain to be clarified. In the current study, we examined the effects of hyperglycemia on cardiac function and myocyte physiology by employing mice with high blood glucose induced by administration of streptozotocin, a compound toxic to insulin-producing β-cells...
January 1, 2017: American Journal of Physiology. Heart and Circulatory Physiology
Yin Hua Zhang
Hypertension is a prevalent condition worldwide and is the key risk factor for fatal cardiovascular complications, such as stroke, sudden cardiac death and heart failure. Reduced bioavailability of nitric oxide (NO) in the endothelium is an important precursor for impaired vasodilation and hypertension. In the heart, NO deficiency deteriorates the adverse consequences of pressure-overload and causes cardiac hypertrophy, fibrosis and myocardial infarction which lead to fatal heart failure and sudden cardiac death...
2016: Clinical Hypertension
Zai Hao Zhao, Jae Boum Youm, Yue Wang, Jeong Hoon Lee, Jae Hwi Sung, Joon-Chul Kim, Sun Hee Woo, Chae Hun Leem, Sung Joon Kim, Lan Cui, Yin Hua Zhang
Fatty acid (FA)-dependent oxidation is the predominant process for energy supply in normal heart. Impaired FA metabolism and metabolic insufficiency underlie the failing of the myocardium. So far, FA metabolism in normal cardiac physiology and heart failure remains undetermined. Here, we evaluate the mechanisms of FA and major metabolic substrates (termed NF) on the contraction, relaxation, and Ca(2+) handling in rat left ventricular (LV) myocytes. Our results showed that NF significantly increased myocyte contraction and facilitated relaxation...
November 2016: Pflügers Archiv: European Journal of Physiology
Wangde Dai, Elissa Cheung, Rick J Alleman, Justin B Perry, Mitchell E Allen, David A Brown, Robert A Kloner
PURPOSE: Dysfunctional mitochondria are considered to be the major source of intracellular reactive oxygen species and play a central role in the pathophysiology of myocardial ischemia/reperfusion. This study sought to determine effects of mitochondria-targeted cytoprotective peptide SBT-20 on myocardial infarct size in two different models of ischemia/reperfusion. METHODS: For in vivo studies, anesthetized Sprague Dawley rats were subjected to 30 min of coronary artery occlusion followed by 3 h of reperfusion...
December 2016: Cardiovascular Drugs and Therapy
Ryan M Broxterman, Phillip F Skiba, Jesse C Craig, Samuel L Wilcox, Carl J Ade, Thomas J Barstow
The sustainable duration of severe intensity exercise is well-predicted by critical power (CP) and the curvature constant (W'). The development of the W'BAL model allows for the pattern of W' expenditure and reconstitution to be characterized and this model has been applied to intermittent exercise protocols. The purpose of this investigation was to assess the influence of relaxation phase duration and exercise intensity on W' reconstitution during dynamic constant power severe intensity exercise. Six men (24...
October 2016: Physiological Reports
Julie Larsen, Peter Bushnell, John Steffensen, Morten Pedersen, Klaus Qvortrup, Richard Brill
We assessed the functional properties in atrial and ventricular myocardium (using isolated cardiac strips) of smooth dogfish (Mustelus canis), clearnose skate (Raja eglanteria), and sandbar shark (Carcharhinus plumbeus) by blocking Ca(2+) release from the sarcoplasmic reticulum (SR) with ryanodine and thapsigargin and measuring the resultant changes in contraction-relaxation parameters and the force-frequency relationship at 20 °C and 30 °C. We also examined ultrastructural differences with electron microscopy...
February 2017: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
Jia Li, Ruping Wang, Dale D Tang
BACKGROUND: The intermediate filament protein vimentin undergoes reversible phosphorylation and dephosphorylation at Ser-56, which plays an important role in regulating the contraction-relaxation cycles of smooth muscle. The protein phosphatases that mediate vimentin dephosphorylation in smooth muscle have not been previously investigated. METHODS: The associations of protein phosphatase 1 (PP1) and protein phosphatase 2A (PP2A) with vimentin in mouse tracheal rings was evaluated by co-immunoprecipitation...
2016: Respiratory Research
Marie C Valenza, Irene Torres-Sánchez, Irene Cabrera-Martos, Gerald Valenza-Demet, Marcelo Cano-Cappellacci
Valenza, MC, Torres-Sánchez, I, Cabrera-Martos, I, Valenza-Demet, G, and Cano-Cappellacci, M. Acute effects of contract-relax stretching vs. TENS in young subjects with anterior knee pain: A randomized controlled trial. J Strength Cond Res 30(8): 2271-2278, 2016-The aim of this study was to examine the immediate effects on pressure point tenderness, range of motion (ROM), and vertical jump (VJ) of contract-relax stretching vs. transcutaneous electrical nerve stimulation (TENS) therapy in individuals with anterior knee pain (AKP)...
August 2016: Journal of Strength and Conditioning Research
Pável Vázquez, Aldo Tirado-Cortés, Rocío Álvarez, Michel Ronjat, Araceli Amaya, Alicia Ortega
The mechanism underlying fatigue in skeletal muscle (SM) related to the redox-potential hypothesis, ranges from a direct effect of oxygen reactive species, to a number of other free radical intermediates targeting specific amino acids in the Ca(2+)-regulatory proteins of the sarcoplasmic reticulum (SR). In the present study, we investigate the selective oxidation/reduction of the protein motif Cys-(Xn=2-6)-Cys, known as a vicinal thiol group (VTG), present in the SR Ca(2+)-ATPase (SERCA) and in the Ca(2+)-channel ryanodine receptor (RyR) which are modified during muscle fatigue in SM...
October 2016: Cell Calcium
Zarife Nigâr Özdemir Kumral, Meltem Kolgazi, Savaş Üstünova, Özgür Kasımay Çakır, Özge Dağdeviren Çevik, Göksel Şener, Berrak Ç Yeğen
Although endogenous estrogen is known to offer cardiac and vascular protection, the involvement of estrogen receptors in mediating the protective effect of estrogen on hypertension-induced cardiovascular and renal injury is not fully explained. We aimed to investigate the effects of estrogen receptor (ER) agonists on oxidative injury, cardiovascular and renal functions of rats with renovascular hypertension (RVH). Female Sprague-Dawley rats were randomly divided as control and RVH groups, and RVH groups had either ovariectomy (OVX) or sham-OVX...
2016: Clinical and Experimental Hypertension: CHE
Shane M Hammer, Jesse C Craig, Ryan M Broxterman, Thomas J Barstow
No abstract text is available yet for this article.
May 2016: Medicine and Science in Sports and Exercise
Qiang Jia, Shanfeng Ma, Xiaofen Liu, Sai Li, Yuanyuan Wang, Qin Gao, Rui Yang
OBJECTIVE: To investigate the effects of hydrogen sulfide (H2S) on contraction capacity of diaphragm in type 1 diabetic rats.
 METHODS: Thirty-two male SD rats were randomly divided into a normal group (NC), a diabetic group (DM), a NaHS treatment group (DM+NaHS) and a NaHS group (NaHS) (n=8). Intraperitoneal injection of streptozotocin was utilized to establish diabetic rat model. After the modeling, the rats in the DM+NaHS and the NaHS groups were intraperitoneally injected with 28 μmol/kg NaHS solution...
May 2016: Zhong Nan da Xue Xue Bao. Yi Xue Ban, Journal of Central South University. Medical Sciences
Minttu Mattila, Juha Koskenvuo, Mirva Söderström, Kim Eerola, Mikko Savontaus
BACKGROUND: Doxorubicin is an effective anticancer drug. The major limitation to its use is the induction of dose-dependent cardiomyopathy. No specific treatment exists for doxorubicin-induced cardiomyopathy and treatments used for other forms of heart failure have only limited beneficial effects. The contraction-relaxation cycle of the heart is controlled by cytosolic calcium concentrations, which, in turn, are critically regulated by the activity of the sarcoplasmic reticulum Ca(2) (+) ATPase (SERCA2a) pump...
July 2016: Journal of Gene Medicine
Andrea Cuíñas, Verónica García-Morales, Dolores Viña, José Gil-Longo, Manuel Campos-Toimil
AIMS: We investigated the implication of PKA and Epac proteins in the endothelium-independent vasorelaxant effects of cyclic AMP (cAMP). MAIN METHODS: Cytosolic Ca(2+) concentration ([Ca(2+)]c) was measured by fura-2 imaging in rat aortic smooth muscle cells (RASMC). Contraction-relaxation experiments were performed in rat aortic rings deprived of endothelium. KEY FINDINGS: In extracellular Ca(2+)-free solution, cAMP-elevating agents induced an increase in [Ca(2+)]c in RASMC that was reproduced by PKA and Epac activation and reduced after depletion of intracellular Ca(2+) reservoirs...
June 15, 2016: Life Sciences
Jonathan Melka, Mario Rienzo, Alain Bizé, Mathieu Jozwiak, Lucien Sambin, Luc Hittinger, Jin Bo Su, Alain Berdeaux, Bijan Ghaleh
Chronic hypertension is associated with left ventricular (LV) hypertrophy and LV diastolic dysfunction with impaired isovolumic relaxation and abnormal LV filling. Increased heart rate (HR) worsens these alterations. We investigated whether the I f channel blocker ivabradine exerts beneficial effects on LV filling dynamic. In this setting, we also evaluated the relationship between LV filling and isovolumic contraction as a consequence of contraction-relaxation coupling. Therefore, hypertension was induced by a continuous infusion of angiotensin II during 28 days in 10 chronically instrumented pigs...
May 2016: Basic Research in Cardiology
Tiankai Li, Heng-Jie Cheng, Nobuyuki Ohte, Hiroshi Hasegawa, Atsushi Morimoto, David M Herrington, William C Little, Weimin Li, Che Ping Cheng
In heart failure (HF), the impaired left ventricular (LV) arterial coupling and diastolic dysfunction present at rest are exacerbated during exercise. C-type natriuretic peptide (CNP) is elevated in HF; however, its functional effects are unclear. We tested the hypotheses that CNP with vasodilating, natriuretic, and positive inotropic and lusitropic actions may prevent this abnormal exercise response after HF. We determined the effects of CNP (2 μg/kg plus 0.4 μg/kg per minute, i.v., 20 minutes) on plasma levels of cGMP before and after HF and assessed LV dynamics during exercise in 10 chronically instrumented dogs with pacing-induced HF...
June 2016: Journal of Pharmacology and Experimental Therapeutics
Motonao Tanaka, Tsuguya Sakamoto, Shigeo Sugawara, Yoshiaki Katahira, Kaoru Hasegawa, Hiroyuki Nakajima, Takafumi Kurokawa, Hiroshi Kanai, Hideyuki Hasegawa
BACKGROUND: Although the deformability of the left ventricular (LV) wall appears to be important in maintaining effective cardiac performance, this has not been debated by anyone, probably owing to the difficulties of the investigation. OBJECTIVES: This study applies a new technology to demonstrate how the LV wall deforms so as to adjust for optimum cardiac performance. SUBJECTS AND METHODS: Ten healthy volunteers were the subjects. Using echo-dynamography, an analysis at the "microscopic" (muscle fiber) level was done by measuring the myocardial axial strain rate (aSR), while the "macroscopic" (muscle layer) level contraction-relaxation/extension (C-R/E) properties of the LV wall were analyzed using high frame rate 2D echocardiography...
February 2017: Journal of Cardiology
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