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The Journal of General Physiology Sep 2022
Topics: Calcium; Excitation Contraction Coupling; Heart; Muscle Contraction; Muscle, Skeletal; Muscle, Smooth
PubMed: 35984377
DOI: 10.1085/jgp.202213244 -
Acta Physiologica (Oxford, England) May 2022
Topics: Mitochondria, Muscle; Muscle Contraction; Organelle Biogenesis
PubMed: 35305290
DOI: 10.1111/apha.13813 -
Journal of Biomechanics Jul 2023Muscle energetics encompasses the relationships between mechanical performance and the biochemical and thermal changes that occur during muscular activity. The... (Review)
Review
Muscle energetics encompasses the relationships between mechanical performance and the biochemical and thermal changes that occur during muscular activity. The biochemical reactions that underpin contraction are described and the way in which these are manifest in experimental recordings, as initial and recovery heat, is illustrated. Energy use during contraction can be partitioned into that related to cross-bridge force generation and that associated with activation by Ca. Activation processes account for 25-45% of ATP turnover in an isometric contraction, varying amongst muscles. Muscle energy use during contraction depends on the nature of the contraction. When shortening muscles produce less force than when contracting isometrically but use energy at a greater rate. These characteristics reflect more rapid cross-bridge cycling when shortening. When lengthening, muscles produce more force than in an isometric contraction but use energy at a lower rate. In that case, cross-bridges cycle but via a pathway in which ATP splitting is not completed. Shortening muscles convert part of the free energy available from ATP hydrolysis into work with the remainder appearing as heat. In the most efficient muscle studied, that of a tortoise, cross-bridges convert a maximum of 47% of the available energy into work. In most other muscles, only 20-30% of the free energy from ATP hydrolysis is converted into work.
Topics: Energy Metabolism; Adenosine Triphosphate; Muscle Contraction; Muscles; Isometric Contraction
PubMed: 37302165
DOI: 10.1016/j.jbiomech.2023.111669 -
The Clinical Journal of Pain 1989Muscle contraction headache is the most common headache afflicting mankind. Acute muscle contraction headache usually presents no problem in treatment and is a... (Review)
Review
Muscle contraction headache is the most common headache afflicting mankind. Acute muscle contraction headache usually presents no problem in treatment and is a self-limited condition. Chronic muscle contraction headache presents a very difficult treatment problem. Patients are often dependent on drugs and treatment usually necessitates a multimodal approach. The pathophysiology of muscle contraction headache is unknown. There is much controversy as to whether muscle contraction is the primary cause of this condition or whether muscle contraction is merely another component of this syndrome. The extensive research now going on in the field of chronic pain should help clarify the issue.
Topics: Headache; Humans; Muscle Contraction
PubMed: 2520384
DOI: 10.1097/00002508-198903000-00008 -
Annual International Conference of the... Jul 2022Smooth muscle is found extensively in the human body, including in blood vessels, airways, the gastrointestinal tract, and the urinary bladder. Although the contractile...
Smooth muscle is found extensively in the human body, including in blood vessels, airways, the gastrointestinal tract, and the urinary bladder. Although the contractile proteins of smooth muscle are very similar to those of striated muscle, smooth muscle's contractile mechanism has not been studied as extensively as those for cardiac and skeletal muscle. Previous studies developed a lumped model of muscle contraction and applied it to cardiac muscle and to skeletal muscle. In this study, this model is used to quantitatively describe the contractile properties of canine smooth muscle, using data from the literature. Results show that a single equation relating muscle force to muscle length and time, and a single set of model parameters, is able to describe smooth muscle's passive and active isometric forces, isometric twitch contractions, isotonic contractions, and an inverse force-velocity relation. The latter arises from the model without assumption of a particular force-velocity curve embodied as a contractile element. This new constitutive relation may be used to describe smooth muscle within larger physiological models, for instance to describe blood vessel constriction or urinary bladder function.
Topics: Animals; Dogs; Humans; Isometric Contraction; Muscle Contraction; Muscle, Skeletal; Muscle, Smooth; Urinary Bladder
PubMed: 36086339
DOI: 10.1109/EMBC48229.2022.9871599 -
Biochemical Pharmacology Feb 2024Extracellular nucleotides and nucleosides are crucial signalling molecules, eliciting diverse biological responses in almost all organs and tissues. These molecules... (Review)
Review
Extracellular nucleotides and nucleosides are crucial signalling molecules, eliciting diverse biological responses in almost all organs and tissues. These molecules exert their effects by activating specific nucleotide receptors, which are finely regulated by ectonucleotidases that break down their ligands. In this comprehensive review, we aim to elucidate the relevance of extracellular nucleotides as signalling molecules in the context of smooth muscle contraction, considering the modulatory influence of ectonucleotidases on this intricate process. Specifically, we provide a detailed examination of the involvement of extracellular nucleotides in the contraction of non-vascular smooth muscles, including those found in the urinary bladder, the airways, the reproductive system, and the gastrointestinal tract. Furthermore, we present a broader overview of the role of extracellular nucleotides in vascular smooth muscle contraction.
Topics: Nucleotides; Muscle Contraction; Urinary Bladder; Nucleosides; Signal Transduction
PubMed: 38142836
DOI: 10.1016/j.bcp.2023.116005 -
International Journal of Molecular... Mar 2023Findings from experiments that used hydrostatic pressure changes to analyse the process of skeletal muscle contraction are re-examined. The force in resting muscle is... (Review)
Review
Findings from experiments that used hydrostatic pressure changes to analyse the process of skeletal muscle contraction are re-examined. The force in resting muscle is insensitive to an increase in hydrostatic pressure from 0.1 MPa (atmospheric) to 10 MPa, as also found for force in rubber-like elastic filaments. The force in rigour muscle rises with increased pressure, as shown experimentally for normal elastic fibres (e.g., glass, collagen, keratin, etc.). In submaximal active contractions, high pressure leads to tension potentiation. The force in maximally activated muscle decreases with increased pressure: the extent of this force decrease in maximal active muscle is sensitive to the concentration of products of ATP hydrolysis (Pi-inorganic phosphate and ADP-adenosine diphosphate) in the medium. When the increased hydrostatic pressure is rapidly decreased, the force recovered to the atmospheric level in all cases. Thus, the resting muscle force remained the same: the force in the rigour muscle decreased in one phase and that in active muscle increased in two phases. The rate of rise of active force on rapid pressure release increased with the concentration of Pi in the medium, indicating that it is coupled to the Pi release step in the ATPase-driven crossbridge cycle in muscle. Pressure experiments on intact muscle illustrate possible underlying mechanisms of tension potentiation and causes of muscle fatigue.
Topics: Hydrostatic Pressure; Muscles; Muscle Contraction; Muscle Fatigue; Adenosine Triphosphatases; Isometric Contraction; Adenosine Triphosphate
PubMed: 36902460
DOI: 10.3390/ijms24055031 -
European Journal of Applied Physiology Nov 2023
Topics: Humans; Muscle Contraction; Muscle Fatigue; Muscle, Skeletal; Potassium
PubMed: 37728786
DOI: 10.1007/s00421-023-05313-1 -
The Review of Scientific Instruments Mar 2023Surface electromyography (sEMG) is considered an established means for controlling prosthetic devices. sEMG suffers from serious issues such as electrical noise, motion...
Surface electromyography (sEMG) is considered an established means for controlling prosthetic devices. sEMG suffers from serious issues such as electrical noise, motion artifact, complex acquisition circuitry, and high measuring costs because of which other techniques have gained attention. This work presents a new optoelectronic muscle (OM) sensor setup as an alternative to the EMG sensor for precise measurement of muscle activity. The sensor integrates a near-infrared light-emitting diode and phototransistor pair along with the suitable driver circuitry. The sensor measures skin surface displacement (that occurs during muscle contraction) by detecting backscattered infrared light from skeletal muscle tissue. With an appropriate signal processing scheme, the sensor was able to produce a 0-5 V output proportional to the muscular contraction. The developed sensor depicted decent static and dynamic features. In detecting muscle contractions from the forearm muscles of subjects, the sensor showed good similarity with the EMG sensor. In addition, the sensor displayed higher signal-to-noise ratio values and better signal stability than the EMG sensor. Furthermore, the OM sensor setup was utilized to control the rotation of the servomotor using an appropriate control scheme. Hence, the developed sensing system can measure muscle contraction information for controlling assistive devices.
Topics: Humans; Upper Extremity; Electromyography; Muscle, Skeletal; Muscle Contraction; Hand; Isometric Contraction
PubMed: 37012764
DOI: 10.1063/5.0130394 -
Annual Review of Physiology 2006Phosphorylation of Ser19 on the 20-kDa regulatory light chain of myosin II (MLC20) by Ca2+/calmodulin-dependent myosin light-chain kinase (MLCK) is essential for... (Review)
Review
Phosphorylation of Ser19 on the 20-kDa regulatory light chain of myosin II (MLC20) by Ca2+/calmodulin-dependent myosin light-chain kinase (MLCK) is essential for initiation of smooth muscle contraction. The initial [Ca2+]i transient is rapidly dissipated and MLCK inactivated, whereas MLC20 and muscle contraction are well maintained. Sustained contraction does not reflect Ca2+ sensitization because complete inhibition of MLC phosphatase activity in the absence of Ca2+ induces smooth muscle contraction. This contraction is suppressed by staurosporine, implying participation of a Ca2+-independent MLCK. Thus, sustained contraction, as with agonist-induced contraction at experimentally fixed Ca2+ concentrations, involves (a) G protein activation, (b) regulated inhibition of MLC phosphatase, and (c) MLC20 phosphorylation via a Ca2+-independent MLCK. The pathways that lead to inhibition of MLC phosphatase by G(q/13)-coupled receptors are initiated by sequential activation of Galpha(q)/alpha13, RhoGEF, and RhoA, and involve Rho kinase-mediated phosphorylation of the regulatory subunit of MLC phosphatase (MYPT1) and/or PKC-mediated phosphorylation of CPI-17, an endogenous inhibitor of MLC phosphatase. Sustained MLC20 phosphorylation is probably induced by the Ca2+-independent MLCK, ZIP kinase. The pathways initiated by G(i)-coupled receptors involve sequential activation of Gbetagamma(i), PI 3-kinase, and the Ca2+-independent MLCK, integrin-linked kinase. The last phosphorylates MLC20 directly and inhibits MLC phosphatase by phosphorylating CPI-17. PKA and PKG, which mediate relaxation, act upstream to desensitize the receptors (VPAC2 and NPR-C), inhibit adenylyl and guanylyl cyclase activities, and stimulate cAMP-specific PDE3 and PDE4 and cGMP-specific PDE5 activities. These kinases also act downstream to inhibit (a) initial contraction by inhibiting Ca2+ mobilization and (b) sustained contraction by inhibiting RhoA and targets downstream of RhoA. This increases MLC phosphatase activity and induces MLC20 dephosphorylation and muscle relaxation.
Topics: Animals; Digestive System Physiological Phenomena; Humans; Muscle Contraction; Muscle Relaxation; Muscle, Smooth; Phosphorylation; Signal Transduction
PubMed: 16460276
DOI: 10.1146/annurev.physiol.68.040504.094707