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The European Respiratory Journal Jun 2019Assessing respiratory mechanics and muscle function is critical for both clinical practice and research purposes. Several methodological developments over the past two... (Review)
Review
Assessing respiratory mechanics and muscle function is critical for both clinical practice and research purposes. Several methodological developments over the past two decades have enhanced our understanding of respiratory muscle function and responses to interventions across the spectrum of health and disease. They are especially useful in diagnosing, phenotyping and assessing treatment efficacy in patients with respiratory symptoms and neuromuscular diseases. Considerable research has been undertaken over the past 17 years, since the publication of the previous American Thoracic Society (ATS)/European Respiratory Society (ERS) statement on respiratory muscle testing in 2002. Key advances have been made in the field of mechanics of breathing, respiratory muscle neurophysiology (electromyography, electroencephalography and transcranial magnetic stimulation) and on respiratory muscle imaging (ultrasound, optoelectronic plethysmography and structured light plethysmography). Accordingly, this ERS task force reviewed the field of respiratory muscle testing in health and disease, with particular reference to data obtained since the previous ATS/ERS statement. It summarises the most recent scientific and methodological developments regarding respiratory mechanics and respiratory muscle assessment by addressing the validity, precision, reproducibility, prognostic value and responsiveness to interventions of various methods. A particular emphasis is placed on assessment during exercise, which is a useful condition to stress the respiratory system.
Topics: Electromyography; Europe; Exercise; Humans; Muscle Strength; Respiratory Function Tests; Respiratory Mechanics; Respiratory Muscles; Rest; Societies, Medical; Transcranial Magnetic Stimulation
PubMed: 30956204
DOI: 10.1183/13993003.01214-2018 -
Pharmacology 2012The relaxant mechanisms of nicorandil were examined by comparing its effects with those of sodium nitroprusside and cromakalim in bovine tracheal smooth muscle. In... (Comparative Study)
Comparative Study
The relaxant mechanisms of nicorandil were examined by comparing its effects with those of sodium nitroprusside and cromakalim in bovine tracheal smooth muscle. In preparations contracted with methacholine (0.3 μ mol/l) or high K(+)(40 mmol/l), nicorandil and sodium nitroprusside caused concentration-dependent relaxations. Their relaxant effects on high K(+) -contracted preparations were smaller than those on methacholine-contracted muscle. Cromakalim relaxed methacholine-contracted preparations, whereas it had no effect on high K(+) -contracted muscle. The inhibitor of soluble guanylyl cyclase 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ; 5 mol/l) completely prevented the relaxation induced by lower concentrations ( <30 μ mol/l) of nicorandil,whereas it partially attenuated relaxation caused by higher concentrations. The ATP-sensitive K(+) (K(ATP)) channel blocker glibenclamide only partially attenuated the relaxant responses to nicorandil (at 100 and 300 μ mol/l). Combination treatment with ODQ and glibenclamide almost completely prevented nicorandil-induced relaxations. The large-conductance Ca2(+) -activated K(+) channel (Maxi K(+) channel) inhibitor iberiotoxin significantly prevented the relaxations induced by lower concentrations (3 and 10 μ mol/l) of nicorandil. The preventive effect of iberiotoxin was markedly enhanced under the blockade of K(ATP) channels with glibenclamide. These results suggest that nicorandil relaxes bovine tracheal smooth muscle through 2 mechanisms: opening of K(ATP) channels and activation of the nitric oxide (NO)-cyclic guanosine monophosphate (cGMP) pathway. Nicorandil may also activate Maxi K(+) channels, possibly through the NO-cGMP pathway, and the interaction of K ATP channels and Maxi K(+) channels may affect the relaxant effect of nicorandilin bovine tracheal smooth muscle.
Topics: Animals; Cattle; Cromakalim; Enzyme Inhibitors; Glyburide; Guanylate Cyclase; In Vitro Techniques; Muscle Relaxation; Muscle, Smooth; Nicorandil; Nitroprusside; Oxadiazoles; Peptides; Quinoxalines; Trachea; Vasodilator Agents
PubMed: 22614221
DOI: 10.1159/000337725 -
Exercise and Sport Sciences Reviews 1981
Comparative Study Review
Topics: Humans; Isometric Contraction; Joints; Muscle Contraction; Muscles; Physical Education and Training; Physical Exertion; Rest; Time Factors
PubMed: 6749520
DOI: No ID Found -
Exercise and Sport Sciences Reviews Apr 2007Force-velocity, force-time, and force-length relations of muscle are typically evaluated with reductionist techniques in which force is measured while the variable of... (Review)
Review
Force-velocity, force-time, and force-length relations of muscle are typically evaluated with reductionist techniques in which force is measured while the variable of interest is manipulated. However, force produced during voluntary movement arises from complex interaction of these contractile characteristics. Nonetheless, neuromuscular performance for cyclical, work-producing movements can be predicted from the interaction of average muscle shortening velocity and movement frequency.
Topics: Biomechanical Phenomena; Exercise; Humans; Movement; Muscle Contraction; Muscle Stretching Exercises; Muscle, Skeletal; Relaxation
PubMed: 17417054
DOI: 10.1097/jes.0b013e31803eb0a0 -
Frontiers in Bioscience : a Journal and... Jan 2001Skeletal muscle and its microvasculature can exhibit remarkable plasticity in response to decreased functional demand (i.e., muscle disuse). Since the microvascular... (Review)
Review
Skeletal muscle and its microvasculature can exhibit remarkable plasticity in response to decreased functional demand (i.e., muscle disuse). Since the microvascular adaptation to disuse does seem to not depend solely on reduced demand, this review examines the various factors that may be responsible for the observed regression of microvascular structure and function during disuse. There are several animal models of muscle disuse; their common feature is that they are associated with a variety of confounding effects that make the interpretation of the "pure" disuse effect challenging. As well, in clinical studies, the effect of disuse can be difficult to separate from that of various pathologies. Regardless of methodological difficulties, degeneration of the capillary wall, capillary loss, arteriolar remodelling, reduced resting state blood flow, and reduced arteriolar responsiveness to acute vasodilative and vasoconstrictive stimuli have all been observed in disused muscles. The level, and presence/absence of these changes may depend on many factors including the duration of disuse, degree of muscle atrophy, residual muscle activity, microvascular blood flow, release of vasoactive agents from the degenerating muscle, muscle type, and the particular pathology associated with the muscle withering in humans. It is the present challenge to discover the presence/absence of key agents (possibly originating at the interface between the blood stream and the vascular wall, within the extracellular matrix, or the muscle fibres themselves) that alter the intra- and/or inter-cellular signalling to explain the mechanism of adaptation of the microvasculature to skeletal muscle disuse.
Topics: Animals; Capillaries; Humans; Immobilization; Microcirculation; Muscle Denervation; Muscle, Skeletal; Regional Blood Flow; Rest
PubMed: 11145925
DOI: 10.2741/tyml -
Journal of the Royal College of... Dec 1990Muscle is a very active metabolic tissue and is frequently injured in sport. The injury heals predominantly by scar tissue which leaves a persistent abnormality within...
Muscle is a very active metabolic tissue and is frequently injured in sport. The injury heals predominantly by scar tissue which leaves a persistent abnormality within the muscle. Prompt treatment and appropriate rehabilitation can minimize the degree of muscle damage and reduce the incidence of later complications.
Topics: Athletic Injuries; Bandages; Hematoma; Humans; Ice; Muscles; Muscular Diseases; Rest; Rupture; Sports Medicine
PubMed: 2079692
DOI: No ID Found -
The Journal of Pharmacy and Pharmacology Nov 1996Tetrazepam is a benzodiazepine derivative clinically used as a muscle relaxant. The aim of the present work was to examine its effect on uterine smooth muscle of the rat...
Tetrazepam is a benzodiazepine derivative clinically used as a muscle relaxant. The aim of the present work was to examine its effect on uterine smooth muscle of the rat in estrus. Tetrazepam required micromolar concentrations to relax contractile responses induced by KCl and acetylcholine in Ca2+ solution, but not oxytocin-induced contraction. In Ca(2+)-free solution, tetrazepam inhibited Ca(2+)-induced contractions in depolarized uterus and vanadate-induced contractions. We suggest that tetrazepam relaxes contractile responses induced by activation of voltage-sensitive calcium channels and receptor-operated calcium channels with little selectivity or that it antagonizes the effect of calcium at subsequent steps, possibly intracellular stores sensitive to vanadate but not sensitive to oxytocin. The inhibition of contraction of rat uterus is not related to high-affinity peripheral benzodiazepine binding sites.
Topics: Animals; Anti-Anxiety Agents; Benzodiazepines; Benzodiazepinones; Calcium; Calcium Channels; Dose-Response Relationship, Drug; Female; Isoquinolines; Muscle Contraction; Muscle Relaxants, Central; Muscle Relaxation; Muscle, Smooth; Potassium Chloride; Rats; Rats, Wistar; Uterus; Vanadates
PubMed: 8961167
DOI: 10.1111/j.2042-7158.1996.tb03915.x -
Molecular Pharmacology Feb 2012The molecular mechanisms involved in uterine quiescence during gestation and those responsible for induction of labor are not completely known. Nitric oxide relaxes...
The molecular mechanisms involved in uterine quiescence during gestation and those responsible for induction of labor are not completely known. Nitric oxide relaxes uterine smooth muscle in a manner disparate from that for other smooth muscles because global elevation of cGMP after activation of soluble guanylyl cyclase does not relax the muscle. S-Nitrosylation, the covalent addition of an nitric oxide (NO) group to a cysteine thiol is a likely mechanism to explain the ability of NO to relax myometrium. This work is the first to describe the myometrial S-nitrosylproteome in both pregnant and nonpregnant tissue states. Using the guinea pig model, we show that specific sets of proteins involved in contraction and relaxation are S-nitrosylated in laboring and nonlaboring muscle and that many of these proteins are uniquely S-nitrosylated in only one state of the tissue. In particular, we show that S-nitrosylation of the intermediate filament protein desmin is significantly increased (5.7-fold, p < 0.005) in pregnancy and that this increase cannot be attributed solely to the increase in protein expression (1.8-fold, p < 0.005) that accompanies pregnancy. Elucidation of the myometrial S-nitrosylproteome provides a list of mechanistically important proteins that can constitute the basis of hypotheses formed to explain the regulation of uterine contraction/relaxation.
Topics: Animals; Female; Guinea Pigs; Humans; Muscle Contraction; Muscle, Smooth; Myometrium; Nitrogen Oxides; Pregnancy; Protein Processing, Post-Translational; Proteome; Uterine Contraction
PubMed: 22027755
DOI: 10.1124/mol.111.075804 -
The Journal of Physiology Jun 2021
Topics: Bed Rest; Muscle, Skeletal; Rest
PubMed: 33896008
DOI: 10.1113/JP281761 -
Medicina (Kaunas, Lithuania) Jun 2022Background and Objectives: Muscle blood flow is impeded during resistance exercise contractions, but immediately increases during recovery. The purpose of this study was...
Background and Objectives: Muscle blood flow is impeded during resistance exercise contractions, but immediately increases during recovery. The purpose of this study was to determine the impact of brief bouts of rest (2 s) between repetitions of resistance exercise on muscle blood flow and exercise tolerance. Materials and Methods: Ten healthy young adults performed single-leg knee extension resistance exercises with no rest between repetitions (i.e., continuous) and with 2 s of rest between each repetition (i.e., intermittent). Exercise tolerance was measured as the maximal power that could be sustained for 3 min (PSUS) and as the maximum number of repetitions (Reps80%) that could be performed at 80% one-repetition maximum (1RM). The leg blood flow, muscle oxygenation of the vastus lateralis and mean arterial pressure (MAP) were measured during various exercise trials. Alpha was set to p ≤ 0.05. Results: Leg blood flow was significantly greater, while vascular resistance and MAP were significantly less during intermittent compared with continuous resistance exercise at the same power outputs (p < 0.01). PSUS was significantly greater during intermittent than continuous resistance exercise (29.5 ± 2.1 vs. 21.7 ± 1.2 W, p = 0.01). Reps80% was also significantly greater during intermittent compared with continuous resistance exercise (26.5 ± 5.3 vs. 16.8 ± 2.1 repetitions, respectively; p = 0.02), potentially due to increased leg blood flow and muscle oxygen saturation during intermittent resistance exercise (p < 0.05). Conclusions: In conclusion, a brief rest between repetitions of resistance exercise effectively decreased vascular resistance, increased blood flow to the exercising muscle, and increased exercise tolerance to resistance exercise.
Topics: Exercise Tolerance; Humans; Muscle, Skeletal; Quadriceps Muscle; Regional Blood Flow; Resistance Training; Rest; Young Adult
PubMed: 35744085
DOI: 10.3390/medicina58060822