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https://www.readbyqxmd.com/read/28213864/electrical-stimulation-of-denervated-rat-skeletal-muscle-ameliorates-bone-fragility-and-muscle-loss-in-early-stage-disuse-musculoskeletal-atrophy
#1
Hiroyuki Tamaki, Kengo Yotani, Futoshi Ogita, Keishi Hayao, Kouki Nakagawa, Kazuhiro Sugawara, Hikari Kirimoto, Hideaki Onishi, Norikatsu Kasuga, Noriaki Yamamoto
We tested whether daily muscle electrical stimulation (ES) can ameliorate the decrease in cortical bone strength as well as muscle and bone geometric and material properties in the early stages of disuse musculoskeletal atrophy. 7-week-old male F344 rats were randomly divided into three groups: age-matched control group (Cont); a sciatic denervation group (DN); and a DN + direct electrical stimulation group (DN + ES). Denervated tibialis anterior (TA) muscle in the DN + ES group received ES with 16 mA at 10 Hz for 30 min/day, 6 days/week...
February 17, 2017: Calcified Tissue International
https://www.readbyqxmd.com/read/28213290/zd0947-a-sulphonylurea-receptor-modulator-detects-functional-sulphonylurea-receptor-subunits-in-murine-vascular-smooth-muscle-atp-sensitive-k-channels
#2
Tadashi Yamamoto, Kohei Takahara, Keiichiro Uchida, Noriyoshi Teramoto
In order to identify functional sulphonylurea receptor (SUR.x) subunits of native ATP-sensitive K(+) channels (KATP channels) in mouse portal vein, the effects of ZD0947, a SUR.x modulator, were investigated on spontaneous portal vein contractions, macroscopic membrane currents and unitary currents recorded (using patch-clamp techniques) in freshly dispersed mouse portal vein myocytes. Spontaneous contractions in mouse portal vein were reversibly reduced by ZD0947 in a concentration-dependent manner (Ki = 293nM)...
February 14, 2017: European Journal of Pharmacology
https://www.readbyqxmd.com/read/28213167/the-effect-of-peripheral-neuropathy-on-lower-limb-muscle-strength-in-diabetic-individuals
#3
Jean P Ferreira, Cristina D Sartor, Ângela M O Leal, Isabel C N Sacco, Tatiana O Sato, Ivana L Ribeiro, Alice S Soares, Jonathan E Cunha, Tania F Salvini
BACKGROUND: Skeletal muscle strength is poorly described and understood in diabetic participants with diabetic peripheral neuropathy. This study aimed to investigate the extensor and flexor torque of the knee and ankle during concentric, eccentric, and isometric contractions in men with diabetes mellitus type 2 with and without diabetic peripheral neuropathy. METHODS: Three groups of adult men (n=92), similar in age, body mass index, and testosterone levels, were analyzed: 33 non-diabetic controls, 31 with type 2 diabetes mellitus, and 28 with diabetic peripheral neuropathy...
February 9, 2017: Clinical Biomechanics
https://www.readbyqxmd.com/read/28212804/potassium-channels-in-regulation-of-vascular-smooth-muscle-contraction-and-growth
#4
W F Jackson
Potassium channels importantly contribute to the regulation of vascular smooth muscle (VSM) contraction and growth. They are the dominant ion conductance of the VSM cell membrane and importantly determine and regulate membrane potential. Membrane potential, in turn, regulates the open-state probability of voltage-gated Ca(2+) channels (VGCC), Ca(2+) influx through VGCC, intracellular Ca(2+), and VSM contraction. Membrane potential also affects release of Ca(2+) from internal stores and the Ca(2+) sensitivity of the contractile machinery such that K(+) channels participate in all aspects of regulation of VSM contraction...
2017: Advances in Pharmacology
https://www.readbyqxmd.com/read/28212803/calcium-channels-in-vascular-smooth-muscle
#5
D Ghosh, A U Syed, M P Prada, M A Nystoriak, L F Santana, M Nieves-Cintrón, M F Navedo
Calcium (Ca(2+)) plays a central role in excitation, contraction, transcription, and proliferation of vascular smooth muscle cells (VSMs). Precise regulation of intracellular Ca(2+) concentration ([Ca(2+)]i) is crucial for proper physiological VSM function. Studies over the last several decades have revealed that VSMs express a variety of Ca(2+)-permeable channels that orchestrate a dynamic, yet finely tuned regulation of [Ca(2+)]i. In this review, we discuss the major Ca(2+)-permeable channels expressed in VSM and their contribution to vascular physiology and pathology...
2017: Advances in Pharmacology
https://www.readbyqxmd.com/read/28212802/smooth-muscle-phenotypic-diversity-effect-on-vascular-function-and-drug-responses
#6
S A Fisher
At its simplest resistance to blood flow is regulated by changes in the state of contraction of the vascular smooth muscle (VSM), a function of the competing activities of the myosin kinase and phosphatase determining the phosphorylation and activity of the myosin ATPase motor protein. In contrast, the vascular system of humans and other mammals is incredibly complex and highly regulated. Much of this complexity derives from phenotypic diversity within the smooth muscle, reflected in very differing power outputs and responses to signaling pathways that regulate vessel tone, presumably having evolved over the millennia to optimize vascular function and its control...
2017: Advances in Pharmacology
https://www.readbyqxmd.com/read/28212799/rho-mancing-to-sensitize-calcium-signaling-for-contraction-in-the-vasculature-role-of-rho-kinase
#7
T Szasz, R C Webb
Vascular smooth muscle contraction is an important physiological process contributing to cardiovascular homeostasis. The principal determinant of smooth muscle contraction is the intracellular free Ca(2+) concentration, and phosphorylation of myosin light chain (MLC) by activated myosin light chain kinase (MLCK) in response to increased Ca(2+) is the main pathway by which vasoconstrictor stimuli induce crossbridge cycling of myosin and actin filaments. A secondary pathway for vascular smooth muscle contraction that is not directly dependent on Ca(2+) concentration, but rather mediating Ca(2+) sensitization, is the RhoA/Rho kinase pathway...
2017: Advances in Pharmacology
https://www.readbyqxmd.com/read/28212798/protein-kinase-c-as-regulator-of-vascular-smooth-muscle-function-and-potential-target-in-vascular-disorders
#8
H C Ringvold, R A Khalil
Vascular smooth muscle (VSM) plays an important role in maintaining vascular tone. In addition to Ca(2+)-dependent myosin light chain (MLC) phosphorylation, protein kinase C (PKC) is a major regulator of VSM function. PKC is a family of conventional Ca(2+)-dependent α, β, and γ, novel Ca(2+)-independent δ, ɛ, θ, and η, and atypical ξ, and ι/λ isoforms. Inactive PKC is mainly cytosolic, and upon activation it undergoes phosphorylation, maturation, and translocation to the surface membrane, the nucleus, endoplasmic reticulum, and other cell organelles; a process facilitated by scaffold proteins such as RACKs...
2017: Advances in Pharmacology
https://www.readbyqxmd.com/read/28212796/sodium-calcium-exchanger-in-pig-coronary-artery
#9
A K Grover
This review focuses on the sodium-calcium exchangers (NCX) in the left anterior descending coronary artery smooth muscle. Bathing tissues in Na(+)-substituted solutions caused them to contract. In cultured smooth muscle cells, it increased the cytosolic Ca(2+) concentration and extracellular entry of (45)Ca(2+). All three activities were attributed to NCX since they were inhibited by NCX inhibitors. The tissues also expressed the sarco/endoplasmic reticulum (SER) Ca(2+) pump SERCA2b whose activity was much greater than that of NCX...
2017: Advances in Pharmacology
https://www.readbyqxmd.com/read/28212795/nanojunctions-of-the-sarcoplasmic-reticulum-deliver-site-and-function-specific-calcium-signaling-in-vascular-smooth-muscles
#10
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/28212264/correlated-emg-oscillations-between-antagonists-during-cocontraction-in-men
#11
Yasuhide Yoshitake, Hiroaki Kanehisa, Minoru Shinohara
PURPOSE: The purpose of this study was to determine the modulation of common low-frequency oscillations in pools of motor units across antagonistic muscles because of the difference in the activation level of pools of spinal motor neurons and the presence of neuromuscular fatigue during intended cocontraction. METHODS: Ten healthy young men (21.8 ± 1.5 yr) performed intended steady cocontractions of elbow flexors and extensors at maximal and a submaximal (10% of maximal EMG) effort...
March 2017: Medicine and Science in Sports and Exercise
https://www.readbyqxmd.com/read/28211794/test-retest-reliability-of-muscle-fiber-conduction-velocity-and-fractal-dimension-of-surface-emg-during-isometric-contractions
#12
Matteo Beretta-Piccoli, Giuseppe D'Antona, Cristian Zampella, Marco Barbero, Ron Clijsen, Corrado Cescon
The aim of this study was to determine the test-retest reliability of muscle fiber conduction velocity (CV) and fractal dimension (FD) obtained from multichannel surface electromyographic (sEMG) recordings. Forty healthy recreationally active subjects (20 men and 20 women) performed two elbow flexions on two trials with a 1-week interval. The first was a 20% maximal voluntary contraction (MVC) of 120 s, and the second at 60% MVC held until exhaustion. sEMG signals were detected from the biceps brachii, using bi-dimensional arrays...
February 17, 2017: Physiological Measurement
https://www.readbyqxmd.com/read/28210319/physiology-of-respiratory-disturbances-in-muscular-dystrophies
#13
Antonella Lo Mauro, Andrea Aliverti
: Muscular dystrophy is a group of inherited myopathies characterised by progressive skeletal muscle wasting, including of the respiratory muscles. Respiratory failure, i.e. when the respiratory system fails in its gas exchange functions, is a common feature in muscular dystrophy, being the main cause of death, and it is a consequence of lung failure, pump failure or a combination of the two. The former is due to recurrent aspiration, the latter to progressive weakness of respiratory muscles and an increase in the load against which they must contract...
December 2016: Breathe
https://www.readbyqxmd.com/read/28210061/therapeutic-effects-of-massage-and-electrotherapy-on-muscle-tone-stiffness-and-muscle-contraction-following-gastrocnemius-muscle-fatigue
#14
Joong-San Wang
[Purpose] This study aimed to examine the effects of a combined intervention consisting of massage therapy and transcutaneous electrical nerve stimulation on gastrocnemius muscle fatigue, assessing whether the intervention improved muscle tone, stiffness, and muscle contraction. [Subjects and Methods] The subjects were 20 healthy males in their 20s who were equally divided into a transcutaneous electrical nerve stimulation group and a combined therapy group that received a combination of massage therapy and transcutaneous electrical nerve stimulation...
January 2017: Journal of Physical Therapy Science
https://www.readbyqxmd.com/read/28209802/doublet-stimulation-increases-ca-2-binding-to-troponin-c-to-ensure-rapid-force-development-in-skeletal-muscle
#15
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/28209743/skeletal-muscle-bioenergetics-during-all-out-exercise-mechanistic-insight-into-the-oxygen-uptake-slow-component-and-neuromuscular-fatigue
#16
Ryan M Broxterman, Gwenael Layec, Thomas J Hureau, Markus Amann, Russell S Richardson
Although commonly used, the physiological mechanisms underlying all-out exercise performance are still unclear and an in-depth assessment of skeletal muscle bioenergetics is lacking. Therefore, phosphorous magnetic resonance spectroscopy ((31)P-MRS) was utilized to assess skeletal muscle bioenergetics during a 5-min all-out intermittent isometric knee-extensor protocol in 8 healthy men. The metabolic perturbation, adenosine triphosphate (ATP) synthesis rates, ATP cost of contraction, and mitochondrial capacity were determined from intramuscular concentrations of phosphocreatine (PCr), inorganic phosphate (Pi), diprotonated phosphate (H2PO4⁻ ), and pH...
February 16, 2017: Journal of Applied Physiology
https://www.readbyqxmd.com/read/28209080/antispasmodic-and-bronchorelaxant-activities-of-salsola-imbricata-are-mediated-through-dual-ca-2-antagonistic-and-%C3%AE-adrenergic-agonistic-effects
#17
Naveed Aslam, Khalid Hussain Janbaz
CONTEXT: Salsola imbricata Forssk. (Chenopodiaceae) has folkloric repute for the treatment of various gastrointestinal and respiratory ailments. OBJECTIVE: The present study investigates spasmolytic and bronchorelaxant effects of S. imbricata. MATERIALS AND METHODS: The crude aqueous-ethanol extract of the aerial parts of S. imbricata and its fractions, in cumulative concentrations (0.01-10 mg/mL), were tested on contractions of isolated rabbit jejunum and tracheal preparations...
December 2017: Pharmaceutical Biology
https://www.readbyqxmd.com/read/28208924/assessment-of-abdominal-muscle-s-maximal-force-of-contraction-using-surface-emg-in-inguinal-hernia-patients
#18
G S Sreenath, Senthil Kumar Subramanian, Vivek Kumar Sharma
INTRODUCTION: Reduction in abdominal muscle's strength has been implicated in the development of inguinal hernia. Patients with inguinal hernia on one side are shown to be at higher risk of developing inguinal hernia on the other side. AIM: To assess the abdominal muscle strength in inguinal hernia subjects using surface Electromyography (EMG) and compare it with healthy controls. MATERIALS AND METHODS: This is a cross-sectional study involving only male subjects...
December 2016: Journal of Clinical and Diagnostic Research: JCDR
https://www.readbyqxmd.com/read/28208809/a-lipid-emulsion-reverses-toxic-dose-bupivacaine-induced-vasodilation-during-tyrosine-phosphorylation-evoked-contraction-in-isolated-rat-aortae
#19
Seong-Ho Ok, Soo Hee Lee, Seong-Chun Kwon, Mun Hwan Choi, Il-Woo Shin, Sebin Kang, Miyeong Park, Jeong-Min Hong, Ju-Tae Sohn
The goal of this in vitro study was to examine the effect of a lipid emulsion on toxic-dose bupivacaine-induced vasodilation in a model of tyrosine phosphatase inhibitor sodium orthovanadate-induced contraction in endothelium-denuded rat aortae and to elucidate the associated cellular mechanism. The effect of a lipid emulsion on vasodilation induced by a toxic dose of a local anesthetic during sodium orthovanadate-induced contraction was examined. In addition, the effects of various inhibitors, either bupivacaine alone or a lipid emulsion plus bupivacaine, on protein kinase phosphorylation induced by sodium orthovanadate in rat aortic vascular smooth muscle cells was examined...
February 13, 2017: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/28208087/morphomechanical-alterations-in-the-medial-gastrocnemius-muscle-in-patients-with-a-repaired-achilles-tendon-associations-with-outcome-measures
#20
Wei-Chen Peng, Yi-Ping Chang, Yuan-Hung Chao, S N Fu, Christer Rolf, Tiffany Tf Shih, Sheng-Chu Su, Hsing-Kuo Wang
BACKGROUND: Functional deficits are found in ankles that have sustained an Achilles rupture. This study sought to evaluate and compare the morphomechanical characteristics of the medial gastrocnemius muscle in the legs of participants within six months of a unilateral Achilles repair to determine any correlations between those characteristics and objective outcomes and self-reported functional levels. METHODS: Fifteen participants were assessed via measurements of muscle morphologies (fascicle length, pennation angle, and muscle thickness) in a resting state, the mechanical properties of the proximal aponeurosis of the medial gastrocnemius muscle, the pennation angle during ramping maximal voluntary isometric contractions (MVIC), the heel raise test, and the Taiwan Chinese version of the Lower Extremity Functional Scale (LEFS-TC) questionnaire...
February 8, 2017: Clinical Biomechanics
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