Muscle Contraction: A process leading to shortening and/or development of tension in muscle tissue. Muscle contraction occurs by a sliding filament mechanism whereby actin filaments slide inward among the myosin filaments.Muscles: Contractile tissue that produces movement in animals.Muscle, Smooth: Unstriated and unstriped muscle, one of the muscles of the internal organs, blood vessels, hair follicles, etc. Contractile elements are elongated, usually spindle-shaped cells with centrally located nuclei. Smooth muscle fibers are bound together into sheets or bundles by reticular fibers and frequently elastic nets are also abundant. (From Stedman, 25th ed)Muscle, Skeletal: A subtype of striated muscle, attached by TENDONS to the SKELETON. Skeletal muscles are innervated and their movement can be consciously controlled. They are also called voluntary muscles.Isometric Contraction: Muscular contractions characterized by increase in tension without change in length.Muscle Proteins: The protein constituents of muscle, the major ones being ACTINS and MYOSINS. More than a dozen accessory proteins exist including TROPONIN; TROPOMYOSIN; and DYSTROPHIN.Muscle, Smooth, Vascular: The nonstriated involuntary muscle tissue of blood vessels.Muscle Fibers, Skeletal: Large, multinucleate single cells, either cylindrical or prismatic in shape, that form the basic unit of SKELETAL MUSCLE. They consist of MYOFIBRILS enclosed within and attached to the SARCOLEMMA. They are derived from the fusion of skeletal myoblasts (MYOBLASTS, SKELETAL) into a syncytium, followed by differentiation.Muscle Fatigue: A state arrived at through prolonged and strong contraction of a muscle. Studies in athletes during prolonged submaximal exercise have shown that muscle fatigue increases in almost direct proportion to the rate of muscle glycogen depletion. Muscle fatigue in short-term maximal exercise is associated with oxygen lack and an increased level of blood and muscle lactic acid, and an accompanying increase in hydrogen-ion concentration in the exercised muscle.Electric Stimulation: Use of electric potential or currents to elicit biological responses.Uterine Contraction: Contraction of the UTERINE MUSCLE.Muscle Development: Developmental events leading to the formation of adult muscular system, which includes differentiation of the various types of muscle cell precursors, migration of myoblasts, activation of myogenesis and development of muscle anchorage.Myocardial Contraction: Contractile activity of the MYOCARDIUM.Muscle Relaxation: That phase of a muscle twitch during which a muscle returns to a resting position.Calcium: A basic element found in nearly all organized tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.Electromyography: Recording of the changes in electric potential of muscle by means of surface or needle electrodes.Muscle Fibers, Fast-Twitch: Skeletal muscle fibers characterized by their expression of the Type II MYOSIN HEAVY CHAIN isoforms which have high ATPase activity and effect several other functional properties - shortening velocity, power output, rate of tension redevelopment. Several fast types have been identified.Muscle Fibers, Slow-Twitch: Skeletal muscle fibers characterized by their expression of the Type I MYOSIN HEAVY CHAIN isoforms which have low ATPase activity and effect several other functional properties - shortening velocity, power output, rate of tension redevelopment.Rabbits: The species Oryctolagus cuniculus, in the family Leporidae, order LAGOMORPHA. Rabbits are born in burrows, furless, and with eyes and ears closed. In contrast with HARES, rabbits have 22 chromosome pairs.Myocytes, Smooth Muscle: Non-striated, elongated, spindle-shaped cells found lining the digestive tract, uterus, and blood vessels. They are derived from specialized myoblasts (MYOBLASTS, SMOOTH MUSCLE).Muscle Spindles: Skeletal muscle structures that function as the MECHANORECEPTORS responsible for the stretch or myotactic reflex (REFLEX, STRETCH). They are composed of a bundle of encapsulated SKELETAL MUSCLE FIBERS, i.e., the intrafusal fibers (nuclear bag 1 fibers, nuclear bag 2 fibers, and nuclear chain fibers) innervated by SENSORY NEURONS.Trachea: The cartilaginous and membranous tube descending from the larynx and branching into the right and left main bronchi.Muscle Denervation: The resection or removal of the innervation of a muscle or muscle tissue.Guinea Pigs: A common name used for the genus Cavia. The most common species is Cavia porcellus which is the domesticated guinea pig used for pets and biomedical research.Muscle, Striated: One of two types of muscle in the body, characterized by the array of bands observed under microscope. Striated muscles can be divided into two subtypes: the CARDIAC MUSCLE and the SKELETAL MUSCLE.Mitochondria, Muscle: Mitochondria of skeletal and smooth muscle. It does not include myocardial mitochondria for which MITOCHONDRIA, HEART is available.Vasoconstriction: The physiological narrowing of BLOOD VESSELS by contraction of the VASCULAR SMOOTH MUSCLE.Papillary Muscles: Conical muscular projections from the walls of the cardiac ventricles, attached to the cusps of the atrioventricular valves by the chordae tendineae.Neck Muscles: The neck muscles consist of the platysma, splenius cervicis, sternocleidomastoid(eus), longus colli, the anterior, medius, and posterior scalenes, digastric(us), stylohyoid(eus), mylohyoid(eus), geniohyoid(eus), sternohyoid(eus), omohyoid(eus), sternothyroid(eus), and thyrohyoid(eus).Myofibrils: The long cylindrical contractile organelles of STRIATED MUSCLE cells composed of ACTIN FILAMENTS; MYOSIN filaments; and other proteins organized in arrays of repeating units called SARCOMERES .Myosins: A diverse superfamily of proteins that function as translocating proteins. They share the common characteristics of being able to bind ACTINS and hydrolyze MgATP. Myosins generally consist of heavy chains which are involved in locomotion, and light chains which are involved in regulation. Within the structure of myosin heavy chain are three domains: the head, the neck and the tail. The head region of the heavy chain contains the actin binding domain and MgATPase domain which provides energy for locomotion. The neck region is involved in binding the light-chains. The tail region provides the anchoring point that maintains the position of the heavy chain. The superfamily of myosins is organized into structural classes based upon the type and arrangement of the subunits they contain.Oculomotor Muscles: The muscles that move the eye. Included in this group are the medial rectus, lateral rectus, superior rectus, inferior rectus, inferior oblique, superior oblique, musculus orbitalis, and levator palpebrae superioris.Peristalsis: A movement, caused by sequential muscle contraction, that pushes the contents of the intestines or other tubular organs in one direction.Motor Neurons: Neurons which activate MUSCLE CELLS.Biomechanical Phenomena: The properties, processes, and behavior of biological systems under the action of mechanical forces.Potassium Chloride: A white crystal or crystalline powder used in BUFFERS; FERTILIZERS; and EXPLOSIVES. It can be used to replenish ELECTROLYTES and restore WATER-ELECTROLYTE BALANCE in treating HYPOKALEMIA.Myosin Light Chains: The smaller subunits of MYOSINS that bind near the head groups of MYOSIN HEAVY CHAINS. The myosin light chains have a molecular weight of about 20 KDa and there are usually one essential and one regulatory pair of light chains associated with each heavy chain. Many myosin light chains that bind calcium are considered "calmodulin-like" proteins.Tropomyosin: A protein found in the thin filaments of muscle fibers. It inhibits contraction of the muscle unless its position is modified by TROPONIN.Hindlimb: Either of two extremities of four-footed non-primate land animals. It usually consists of a FEMUR; TIBIA; and FIBULA; tarsals; METATARSALS; and TOES. (From Storer et al., General Zoology, 6th ed, p73)Time Factors: Elements of limited time intervals, contributing to particular results or situations.Respiratory Muscles: These include the muscles of the DIAPHRAGM and the INTERCOSTAL MUSCLES.Isotonic Contraction: Muscle contraction with negligible change in the force of contraction but shortening of the distance between the origin and insertion.Muscle Weakness: A vague complaint of debility, fatigue, or exhaustion attributable to weakness of various muscles. The weakness can be characterized as subacute or chronic, often progressive, and is a manifestation of many muscle and neuromuscular diseases. (From Wyngaarden et al., Cecil Textbook of Medicine, 19th ed, p2251)Abdominal Muscles: Muscles forming the ABDOMINAL WALL including RECTUS ABDOMINIS, external and internal oblique muscles, transversus abdominis, and quadratus abdominis. (from Stedman, 25th ed)Acetylcholine: A neurotransmitter found at neuromuscular junctions, autonomic ganglia, parasympathetic effector junctions, a subset of sympathetic effector junctions, and at many sites in the central nervous system.Actins: Filamentous proteins that are the main constituent of the thin filaments of muscle fibers. The filaments (known also as filamentous or F-actin) can be dissociated into their globular subunits; each subunit is composed of a single polypeptide 375 amino acids long. This is known as globular or G-actin. In conjunction with MYOSINS, actin is responsible for the contraction and relaxation of muscle.Quadriceps Muscle: The quadriceps femoris. A collective name of the four-headed skeletal muscle of the thigh, comprised of the rectus femoris, vastus intermedius, vastus lateralis, and vastus medialis.Rats, Sprague-Dawley: A strain of albino rat used widely for experimental purposes because of its calmness and ease of handling. It was developed by the Sprague-Dawley Animal Company.Sarcomeres: The repeating contractile units of the MYOFIBRIL, delimited by Z bands along its length.Troponin C: One of the three polypeptide chains that make up the TROPONIN complex of skeletal muscle. It is a calcium-binding protein.Rats, Wistar: A strain of albino rat developed at the Wistar Institute that has spread widely at other institutions. This has markedly diluted the original strain.Muscle Cells: Mature contractile cells, commonly known as myocytes, that form one of three kinds of muscle. The three types of muscle cells are skeletal (MUSCLE FIBERS, SKELETAL), cardiac (MYOCYTES, CARDIAC), and smooth (MYOCYTES, SMOOTH MUSCLE). They are derived from embryonic (precursor) muscle cells called MYOBLASTS.Facial Muscles: Muscles of facial expression or mimetic muscles that include the numerous muscles supplied by the facial nerve that are attached to and move the skin of the face. (From Stedman, 25th ed)Dose-Response Relationship, Drug: The relationship between the dose of an administered drug and the response of the organism to the drug.Gastrointestinal Motility: The motor activity of the GASTROINTESTINAL TRACT.Torque: The rotational force about an axis that is equal to the product of a force times the distance from the axis where the force is applied.Urinary Bladder: A musculomembranous sac along the URINARY TRACT. URINE flows from the KIDNEYS into the bladder via the ureters (URETER), and is held there until URINATION.Carbachol: A slowly hydrolyzed CHOLINERGIC AGONIST that acts at both MUSCARINIC RECEPTORS and NICOTINIC RECEPTORS.Masticatory Muscles: Muscles arising in the zygomatic arch that close the jaw. Their nerve supply is masseteric from the mandibular division of the trigeminal nerve. (From Stedman, 25th ed)rho-Associated Kinases: A group of intracellular-signaling serine threonine kinases that bind to RHO GTP-BINDING PROTEINS. They were originally found to mediate the effects of rhoA GTP-BINDING PROTEIN on the formation of STRESS FIBERS and FOCAL ADHESIONS. Rho-associated kinases have specificity for a variety of substrates including MYOSIN-LIGHT-CHAIN PHOSPHATASE and LIM KINASES.Muscle Tonus: The state of activity or tension of a muscle beyond that related to its physical properties, that is, its active resistance to stretch. In skeletal muscle, tonus is dependent upon efferent innervation. (Stedman, 25th ed)Diaphragm: The musculofibrous partition that separates the THORACIC CAVITY from the ABDOMINAL CAVITY. Contraction of the diaphragm increases the volume of the thoracic cavity aiding INHALATION.Neuromuscular Junction: The synapse between a neuron and a muscle.Vasoconstrictor Agents: Drugs used to cause constriction of the blood vessels.Dogs: The domestic dog, Canis familiaris, comprising about 400 breeds, of the carnivore family CANIDAE. They are worldwide in distribution and live in association with people. (Walker's Mammals of the World, 5th ed, p1065)Cats: The domestic cat, Felis catus, of the carnivore family FELIDAE, comprising over 30 different breeds. The domestic cat is descended primarily from the wild cat of Africa and extreme southwestern Asia. Though probably present in towns in Palestine as long ago as 7000 years, actual domestication occurred in Egypt about 4000 years ago. (From Walker's Mammals of the World, 6th ed, p801)Physical Exertion: Expenditure of energy during PHYSICAL ACTIVITY. Intensity of exertion may be measured by rate of OXYGEN CONSUMPTION; HEAT produced, or HEART RATE. Perceived exertion, a psychological measure of exertion, is included.Actomyosin: A protein complex of actin and MYOSINS occurring in muscle. It is the essential contractile substance of muscle.Phenylephrine: An alpha-1 adrenergic agonist used as a mydriatic, nasal decongestant, and cardiotonic agent.Psoas Muscles: A powerful flexor of the thigh at the hip joint (psoas major) and a weak flexor of the trunk and lumbar spinal column (psoas minor). Psoas is derived from the Greek "psoa", the plural meaning "muscles of the loin". It is a common site of infection manifesting as abscess (PSOAS ABSCESS). The psoas muscles and their fibers are also used frequently in experiments in muscle physiology.Troponin: One of the minor protein components of skeletal muscle. Its function is to serve as the calcium-binding component in the troponin-tropomyosin B-actin-myosin complex by conferring calcium sensitivity to the cross-linked actin and myosin filaments.Models, Biological: Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.Adenosine Triphosphate: An adenine nucleotide containing three phosphate groups esterified to the sugar moiety. In addition to its crucial roles in metabolism adenosine triphosphate is a neurotransmitter.Ileum: The distal and narrowest portion of the SMALL INTESTINE, between the JEJUNUM and the ILEOCECAL VALVE of the LARGE INTESTINE.Reflex: An involuntary movement or exercise of function in a part, excited in response to a stimulus applied to the periphery and transmitted to the brain or spinal cord.Cells, Cultured: Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others.Masseter Muscle: A masticatory muscle whose action is closing the jaws.Norepinephrine: Precursor of epinephrine that is secreted by the adrenal medulla and is a widespread central and autonomic neurotransmitter. Norepinephrine is the principal transmitter of most postganglionic sympathetic fibers and of the diffuse projection system in the brain arising from the locus ceruleus. It is also found in plants and is used pharmacologically as a sympathomimetic.Muscular Diseases: Acquired, familial, and congenital disorders of SKELETAL MUSCLE and SMOOTH MUSCLE.Intercostal Muscles: Respiratory muscles that arise from the lower border of one rib and insert into the upper border of the adjoining rib, and contract during inspiration or respiration. (From Stedman, 25th ed)Caffeine: A methylxanthine naturally occurring in some beverages and also used as a pharmacological agent. Caffeine's most notable pharmacological effect is as a central nervous system stimulant, increasing alertness and producing agitation. It also relaxes SMOOTH MUSCLE, stimulates CARDIAC MUSCLE, stimulates DIURESIS, and appears to be useful in the treatment of some types of headache. Several cellular actions of caffeine have been observed, but it is not entirely clear how each contributes to its pharmacological profile. Among the most important are inhibition of cyclic nucleotide PHOSPHODIESTERASES, antagonism of ADENOSINE RECEPTORS, and modulation of intracellular calcium handling.Phosphorylation: The introduction of a phosphoryl group into a compound through the formation of an ester bond between the compound and a phosphorus moiety.Myosin-Light-Chain Kinase: An enzyme that phosphorylates myosin light chains in the presence of ATP to yield myosin-light chain phosphate and ADP, and requires calcium and CALMODULIN. The 20-kDa light chain is phosphorylated more rapidly than any other acceptor, but light chains from other myosins and myosin itself can act as acceptors. The enzyme plays a central role in the regulation of smooth muscle contraction.Atropine: An alkaloid, originally from Atropa belladonna, but found in other plants, mainly SOLANACEAE. Hyoscyamine is the 3(S)-endo isomer of atropine.Myocardium: The muscle tissue of the HEART. It is composed of striated, involuntary muscle cells (MYOCYTES, CARDIAC) connected to form the contractile pump to generate blood flow.Aorta, Thoracic: The portion of the descending aorta proceeding from the arch of the aorta and extending to the DIAPHRAGM, eventually connecting to the ABDOMINAL AORTA.Myography: The recording of muscular movements. The apparatus is called a myograph, the record or tracing, a myogram. (From Stedman, 25th ed)Stress, Mechanical: A purely physical condition which exists within any material because of strain or deformation by external forces or by non-uniform thermal expansion; expressed quantitatively in units of force per unit area.Potassium: An element in the alkali group of metals with an atomic symbol K, atomic number 19, and atomic weight 39.10. It is the chief cation in the intracellular fluid of muscle and other cells. Potassium ion is a strong electrolyte that plays a significant role in the regulation of fluid volume and maintenance of the WATER-ELECTROLYTE BALANCE.Muscular Atrophy: Derangement in size and number of muscle fibers occurring with aging, reduction in blood supply, or following immobilization, prolonged weightlessness, malnutrition, and particularly in denervation.Actin Cytoskeleton: Fibers composed of MICROFILAMENT PROTEINS, which are predominately ACTIN. They are the smallest of the cytoskeletal filaments.Enzyme Inhibitors: Compounds or agents that combine with an enzyme in such a manner as to prevent the normal substrate-enzyme combination and the catalytic reaction.Kinetics: The rate dynamics in chemical or physical systems.Myosin Heavy Chains: The larger subunits of MYOSINS. The heavy chains have a molecular weight of about 230 kDa and each heavy chain is usually associated with a dissimilar pair of MYOSIN LIGHT CHAINS. The heavy chains possess actin-binding and ATPase activity.Cholinergic Agonists: Drugs that bind to and activate cholinergic receptors.Calcium Signaling: Signal transduction mechanisms whereby calcium mobilization (from outside the cell or from intracellular storage pools) to the cytoplasm is triggered by external stimuli. Calcium signals are often seen to propagate as waves, oscillations, spikes, sparks, or puffs. The calcium acts as an intracellular messenger by activating calcium-responsive proteins.Myosin-Light-Chain Phosphatase: A phosphoprotein phosphatase that is specific for MYOSIN LIGHT CHAINS. It is composed of three subunits, which include a catalytic subunit, a myosin binding subunit, and a third subunit of unknown function.Aorta: The main trunk of the systemic arteries.Signal Transduction: The intracellular transfer of information (biological activation/inhibition) through a signal pathway. In each signal transduction system, an activation/inhibition signal from a biologically active molecule (hormone, neurotransmitter) is mediated via the coupling of a receptor/enzyme to a second messenger system or to an ion channel. Signal transduction plays an important role in activating cellular functions, cell differentiation, and cell proliferation. Examples of signal transduction systems are the GAMMA-AMINOBUTYRIC ACID-postsynaptic receptor-calcium ion channel system, the receptor-mediated T-cell activation pathway, and the receptor-mediated activation of phospholipases. Those coupled to membrane depolarization or intracellular release of calcium include the receptor-mediated activation of cytotoxic functions in granulocytes and the synaptic potentiation of protein kinase activation. Some signal transduction pathways may be part of larger signal transduction pathways; for example, protein kinase activation is part of the platelet activation signal pathway.Sarcoplasmic Reticulum: A network of tubules and sacs in the cytoplasm of SKELETAL MUSCLE FIBERS that assist with muscle contraction and relaxation by releasing and storing calcium ions.Pressure: A type of stress exerted uniformly in all directions. Its measure is the force exerted per unit area. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Action Potentials: Abrupt changes in the membrane potential that sweep along the CELL MEMBRANE of excitable cells in response to excitation stimuli.Tendons: Fibrous bands or cords of CONNECTIVE TISSUE at the ends of SKELETAL MUSCLE FIBERS that serve to attach the MUSCLES to bones and other structures.Smooth Muscle Myosins: Myosin type II isoforms found in smooth muscle.Serotonin: A biochemical messenger and regulator, synthesized from the essential amino acid L-TRYPTOPHAN. In humans it is found primarily in the central nervous system, gastrointestinal tract, and blood platelets. Serotonin mediates several important physiological functions including neurotransmission, gastrointestinal motility, hemostasis, and cardiovascular integrity. Multiple receptor families (RECEPTORS, SEROTONIN) explain the broad physiological actions and distribution of this biochemical mediator.Nifedipine: A potent vasodilator agent with calcium antagonistic action. It is a useful anti-anginal agent that also lowers blood pressure.Reflex, Stretch: Reflex contraction of a muscle in response to stretching, which stimulates muscle proprioceptors.GlycogenSatellite Cells, Skeletal Muscle: Elongated, spindle-shaped, quiescent myoblasts lying in close contact with adult skeletal muscle. They are thought to play a role in muscle repair and regeneration.Regional Blood Flow: The flow of BLOOD through or around an organ or region of the body.Membrane Potentials: The voltage differences across a membrane. For cellular membranes they are computed by subtracting the voltage measured outside the membrane from the voltage measured inside the membrane. They result from differences of inside versus outside concentration of potassium, sodium, chloride, and other ions across cells' or ORGANELLES membranes. For excitable cells, the resting membrane potentials range between -30 and -100 millivolts. Physical, chemical, or electrical stimuli can make a membrane potential more negative (hyperpolarization), or less negative (depolarization).Calcium Channel Blockers: A class of drugs that act by selective inhibition of calcium influx through cellular membranes.Leg: The inferior part of the lower extremity between the KNEE and the ANKLE.15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid: A stable prostaglandin endoperoxide analog which serves as a thromboxane mimetic. Its actions include mimicking the hydro-osmotic effect of VASOPRESSIN and activation of TYPE C PHOSPHOLIPASES. (From J Pharmacol Exp Ther 1983;224(1): 108-117; Biochem J 1984;222(1):103-110)Movement: The act, process, or result of passing from one place or position to another. It differs from LOCOMOTION in that locomotion is restricted to the passing of the whole body from one place to another, while movement encompasses both locomotion but also a change of the position of the whole body or any of its parts. Movement may be used with reference to humans, vertebrate and invertebrate animals, and microorganisms. Differentiate also from MOTOR ACTIVITY, movement associated with behavior.Exercise: Physical activity which is usually regular and done with the intention of improving or maintaining PHYSICAL FITNESS or HEALTH. Contrast with PHYSICAL EXERTION which is concerned largely with the physiologic and metabolic response to energy expenditure.Histamine: An amine derived by enzymatic decarboxylation of HISTIDINE. It is a powerful stimulant of gastric secretion, a constrictor of bronchial smooth muscle, a vasodilator, and also a centrally acting neurotransmitter.Arteries: The vessels carrying blood away from the heart.Esophagus: The muscular membranous segment between the PHARYNX and the STOMACH in the UPPER GASTROINTESTINAL TRACT.Phosphocreatine: An endogenous substance found mainly in skeletal muscle of vertebrates. It has been tried in the treatment of cardiac disorders and has been added to cardioplegic solutions. (Reynolds JEF(Ed): Martindale: The Extra Pharmacopoeia (electronic version). Micromedex, Inc, Englewood, CO, 1996)Pectoralis Muscles: The pectoralis major and pectoralis minor muscles that make up the upper and fore part of the chest in front of the AXILLA.Anura: An order of the class Amphibia, which includes several families of frogs and toads. They are characterized by well developed hind limbs adapted for jumping, fused head and trunk and webbed toes. The term "toad" is ambiguous and is properly applied only to the family Bufonidae.Heart: The hollow, muscular organ that maintains the circulation of the blood.Troponin I: One of the three polypeptide chains that make up the TROPONIN complex. It inhibits F-actin-myosin interactions.Mesenteric Arteries: Arteries which arise from the abdominal aorta and distribute to most of the intestines.Vas Deferens: The excretory duct of the testes that carries SPERMATOZOA. It rises from the SCROTUM and joins the SEMINAL VESICLES to form the ejaculatory duct.Physical Endurance: The time span between the beginning of physical activity by an individual and the termination because of exhaustion.Muscle Cramp: A sustained and usually painful contraction of muscle fibers. This may occur as an isolated phenomenon or as a manifestation of an underlying disease process (e.g., UREMIA; HYPOTHYROIDISM; MOTOR NEURON DISEASE; etc.). (From Adams et al., Principles of Neurology, 6th ed, p1398)Recruitment, Neurophysiological: The spread of response if stimulation is prolonged. (Campbell's Psychiatric Dictionary, 8th ed.)Electrophysiology: The study of the generation and behavior of electrical charges in living organisms particularly the nervous system and the effects of electricity on living organisms.Bronchi: The larger air passages of the lungs arising from the terminal bifurcation of the TRACHEA. They include the largest two primary bronchi which branch out into secondary bronchi, and tertiary bronchi which extend into BRONCHIOLES and PULMONARY ALVEOLI.Myosin Subfragments: Parts of the myosin molecule resulting from cleavage by proteolytic enzymes (PAPAIN; TRYPSIN; or CHYMOTRYPSIN) at well-localized regions. Study of these isolated fragments helps to delineate the functional roles of different parts of myosin. Two of the most common subfragments are myosin S-1 and myosin S-2. S-1 contains the heads of the heavy chains plus the light chains and S-2 contains part of the double-stranded, alpha-helical, heavy chain tail (myosin rod).Vasodilation: The physiological widening of BLOOD VESSELS by relaxing the underlying VASCULAR SMOOTH MUSCLE.Oxygen Consumption: The rate at which oxygen is used by a tissue; microliters of oxygen STPD used per milligram of tissue per hour; the rate at which oxygen enters the blood from alveolar gas, equal in the steady state to the consumption of oxygen by tissue metabolism throughout the body. (Stedman, 25th ed, p346)Elbow: Region of the body immediately surrounding and including the ELBOW JOINT.RNA, Messenger: RNA sequences that serve as templates for protein synthesis. Bacterial mRNAs are generally primary transcripts in that they do not require post-transcriptional processing. Eukaryotic mRNA is synthesized in the nucleus and must be exported to the cytoplasm for translation. Most eukaryotic mRNAs have a sequence of polyadenylic acid at the 3' end, referred to as the poly(A) tail. The function of this tail is not known for certain, but it may play a role in the export of mature mRNA from the nucleus as well as in helping stabilize some mRNA molecules by retarding their degradation in the cytoplasm.Evoked Potentials, Motor: The electrical response evoked in a muscle or motor nerve by electrical or magnetic stimulation. Common methods of stimulation are by transcranial electrical and TRANSCRANIAL MAGNETIC STIMULATION. It is often used for monitoring during neurosurgery.Energy Metabolism: The chemical reactions involved in the production and utilization of various forms of energy in cells.Elasticity: Resistance and recovery from distortion of shape.Ryanodine: A methylpyrrole-carboxylate from RYANIA that disrupts the RYANODINE RECEPTOR CALCIUM RELEASE CHANNEL to modify CALCIUM release from SARCOPLASMIC RETICULUM resulting in alteration of MUSCLE CONTRACTION. It was previously used in INSECTICIDES. It is used experimentally in conjunction with THAPSIGARGIN and other inhibitors of CALCIUM ATPASE uptake of calcium into SARCOPLASMIC RETICULUM.Molecular Sequence Data: Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.Muscular Dystrophy, AnimalMuscarinic Antagonists: Drugs that bind to but do not activate MUSCARINIC RECEPTORS, thereby blocking the actions of endogenous ACETYLCHOLINE or exogenous agonists. Muscarinic antagonists have widespread effects including actions on the iris and ciliary muscle of the eye, the heart and blood vessels, secretions of the respiratory tract, GI system, and salivary glands, GI motility, urinary bladder tone, and the central nervous system.Mechanoreceptors: Cells specialized to transduce mechanical stimuli and relay that information centrally in the nervous system. Mechanoreceptor cells include the INNER EAR hair cells, which mediate hearing and balance, and the various somatosensory receptors, often with non-neural accessory structures.Chickens: Common name for the species Gallus gallus, the domestic fowl, in the family Phasianidae, order GALLIFORMES. It is descended from the red jungle fowl of SOUTHEAST ASIA.Temporal Muscle: A masticatory muscle whose action is closing the jaws; its posterior portion retracts the mandible.Calmodulin-Binding Proteins: Proteins which bind calmodulin. They are found in many tissues and have a variety of functions including F-actin cross-linking properties, inhibition of cyclic nucleotide phosphodiesterase and calcium and magnesium ATPases.Tetrodotoxin: An aminoperhydroquinazoline poison found mainly in the liver and ovaries of fishes in the order TETRAODONTIFORMES, which are eaten. The toxin causes paresthesia and paralysis through interference with neuromuscular conduction.Sarcolemma: The excitable plasma membrane of a muscle cell. (Glick, Glossary of Biochemistry and Molecular Biology, 1990)Verapamil: A calcium channel blocker that is a class IV anti-arrhythmia agent.Calcium Channels: Voltage-dependent cell membrane glycoproteins selectively permeable to calcium ions. They are categorized as L-, T-, N-, P-, Q-, and R-types based on the activation and inactivation kinetics, ion specificity, and sensitivity to drugs and toxins. The L- and T-types are present throughout the cardiovascular and central nervous systems and the N-, P-, Q-, & R-types are located in neuronal tissue.Volition: Voluntary activity without external compulsion.Blood Pressure: PRESSURE of the BLOOD on the ARTERIES and other BLOOD VESSELS.Ryanodine Receptor Calcium Release Channel: A tetrameric calcium release channel in the SARCOPLASMIC RETICULUM membrane of SMOOTH MUSCLE CELLS, acting oppositely to SARCOPLASMIC RETICULUM CALCIUM-TRANSPORTING ATPASES. It is important in skeletal and cardiac excitation-contraction coupling and studied by using RYANODINE. Abnormalities are implicated in CARDIAC ARRHYTHMIAS and MUSCULAR DISEASES.Amides: Organic compounds containing the -CO-NH2 radical. Amides are derived from acids by replacement of -OH by -NH2 or from ammonia by the replacement of H by an acyl group. (From Grant & Hackh's Chemical Dictionary, 5th ed)Nitric Oxide: A free radical gas produced endogenously by a variety of mammalian cells, synthesized from ARGININE by NITRIC OXIDE SYNTHASE. Nitric oxide is one of the ENDOTHELIUM-DEPENDENT RELAXING FACTORS released by the vascular endothelium and mediates VASODILATION. It also inhibits platelet aggregation, induces disaggregation of aggregated platelets, and inhibits platelet adhesion to the vascular endothelium. Nitric oxide activates cytosolic GUANYLATE CYCLASE and thus elevates intracellular levels of CYCLIC GMP.Adrenergic alpha-Agonists: Drugs that selectively bind to and activate alpha adrenergic receptors.Manometry: Measurement of the pressure or tension of liquids or gases with a manometer.Locomotion: Movement or the ability to move from one place or another. It can refer to humans, vertebrate or invertebrate animals, and microorganisms.Mice, Inbred C57BLHeart Rate: The number of times the HEART VENTRICLES contract per unit of time, usually per minute.Thigh: The portion of the leg in humans and other animals found between the HIP and KNEE.Myometrium: The smooth muscle coat of the uterus, which forms the main mass of the organ.Indoles: Benzopyrroles with the nitrogen at the number one carbon adjacent to the benzyl portion, in contrast to ISOINDOLES which have the nitrogen away from the six-membered ring.Protein Isoforms: Different forms of a protein that may be produced from different GENES, or from the same gene by ALTERNATIVE SPLICING.Aging: The gradual irreversible changes in structure and function of an organism that occur as a result of the passage of time.Analysis of Variance: A statistical technique that isolates and assesses the contributions of categorical independent variables to variation in the mean of a continuous dependent variable.Pharyngeal Muscles: The muscles of the PHARYNX are voluntary muscles arranged in two layers. The external circular layer consists of three constrictors (superior, middle, and inferior). The internal longitudinal layer consists of the palatopharyngeus, the salpingopharyngeus, and the stylopharyngeus. During swallowing, the outer layer constricts the pharyngeal wall and the inner layer elevates pharynx and LARYNX.Knee: A region of the lower extremity immediately surrounding and including the KNEE JOINT.Stomach: An organ of digestion situated in the left upper quadrant of the abdomen between the termination of the ESOPHAGUS and the beginning of the DUODENUM.H-Reflex: A monosynaptic reflex elicited by stimulating a nerve, particularly the tibial nerve, with an electric shock.Amino Acid Sequence: The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.Endothelin-1: A 21-amino acid peptide produced in a variety of tissues including endothelial and vascular smooth-muscle cells, neurons and astrocytes in the central nervous system, and endometrial cells. It acts as a modulator of vasomotor tone, cell proliferation, and hormone production. (N Eng J Med 1995;333(6):356-63)Glucose: A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement.Neurons, Afferent: Neurons which conduct NERVE IMPULSES to the CENTRAL NERVOUS SYSTEM.Arterioles: The smallest divisions of the arteries located between the muscular arteries and the capillaries.Indomethacin: A non-steroidal anti-inflammatory agent (NSAID) that inhibits the enzyme cyclooxygenase necessary for the formation of prostaglandins and other autacoids. It also inhibits the motility of polymorphonuclear leukocytes.Aminoimidazole Carboxamide: An imidazole derivative which is a metabolite of the antineoplastic agents BIC and DIC. By itself, or as the ribonucleotide, it is used as a condensation agent in the preparation of nucleosides and nucleotides. Compounded with orotic acid, it is used to treat liver diseases.Gastric Fundus: The superior portion of the body of the stomach above the level of the cardiac notch.Pelvic Floor: Soft tissue formed mainly by the pelvic diaphragm, which is composed of the two levator ani and two coccygeus muscles. The pelvic diaphragm lies just below the pelvic aperture (outlet) and separates the pelvic cavity from the PERINEUM. It extends between the PUBIC BONE anteriorly and the COCCYX posteriorly.Hand Strength: Force exerted when gripping or grasping.Substance P: An eleven-amino acid neurotransmitter that appears in both the central and peripheral nervous systems. It is involved in transmission of PAIN, causes rapid contractions of the gastrointestinal smooth muscle, and modulates inflammatory and immune responses.Adaptation, Physiological: The non-genetic biological changes of an organism in response to challenges in its ENVIRONMENT.Protein Kinase C: An serine-threonine protein kinase that requires the presence of physiological concentrations of CALCIUM and membrane PHOSPHOLIPIDS. The additional presence of DIACYLGLYCEROLS markedly increases its sensitivity to both calcium and phospholipids. The sensitivity of the enzyme can also be increased by PHORBOL ESTERS and it is believed that protein kinase C is the receptor protein of tumor-promoting phorbol esters.Excitation Contraction Coupling: A process fundamental to muscle physiology whereby an electrical stimulus or action potential triggers a myocyte to depolarize and contract. This mechanical muscle contraction response is regulated by entry of calcium ions into the cell.Myoblasts: Embryonic (precursor) cells of the myogenic lineage that develop from the MESODERM. They undergo proliferation, migrate to their various sites, and then differentiate into the appropriate form of myocytes (MYOCYTES, SKELETAL; MYOCYTES, CARDIAC; MYOCYTES, SMOOTH MUSCLE).Muscle Rigidity: Continuous involuntary sustained muscle contraction which is often a manifestation of BASAL GANGLIA DISEASES. When an affected muscle is passively stretched, the degree of resistance remains constant regardless of the rate at which the muscle is stretched. This feature helps to distinguish rigidity from MUSCLE SPASTICITY. (From Adams et al., Principles of Neurology, 6th ed, p73)Esophageal Sphincter, Lower: The physiologic or functional barrier to GASTROESOPHAGEAL REFLUX at the esophagogastric junction. Sphincteric muscles remain tonically contracted during the resting state and form the high-pressure zone separating the lumen of the ESOPHAGUS from that of the STOMACH. (Haubrich et al, Bockus Gastroenterology, 5th ed., pp399, 415)Bronchoconstriction: Narrowing of the caliber of the BRONCHI, physiologically or as a result of pharmacological intervention.Rats, Inbred Strains: Genetically identical individuals developed from brother and sister matings which have been carried out for twenty or more generations or by parent x offspring matings carried out with certain restrictions. This also includes animals with a long history of closed colony breeding.Mice, Knockout: Strains of mice in which certain GENES of their GENOMES have been disrupted, or "knocked-out". To produce knockouts, using RECOMBINANT DNA technology, the normal DNA sequence of the gene being studied is altered to prevent synthesis of a normal gene product. Cloned cells in which this DNA alteration is successful are then injected into mouse EMBRYOS to produce chimeric mice. The chimeric mice are then bred to yield a strain in which all the cells of the mouse contain the disrupted gene. Knockout mice are used as EXPERIMENTAL ANIMAL MODELS for diseases (DISEASE MODELS, ANIMAL) and to clarify the functions of the genes.Troponin T: One of the three polypeptide chains that make up the TROPONIN complex. It is a cardiac-specific protein that binds to TROPOMYOSIN. It is released from damaged or injured heart muscle cells (MYOCYTES, CARDIAC). Defects in the gene encoding troponin T result in FAMILIAL HYPERTROPHIC CARDIOMYOPATHY.Paralysis: A general term most often used to describe severe or complete loss of muscle strength due to motor system disease from the level of the cerebral cortex to the muscle fiber. This term may also occasionally refer to a loss of sensory function. (From Adams et al., Principles of Neurology, 6th ed, p45)Receptor, Muscarinic M3: A subclass of muscarinic receptor that mediates cholinergic-induced contraction in a variety of SMOOTH MUSCLES.Decerebrate State: A condition characterized by abnormal posturing of the limbs that is associated with injury to the brainstem. This may occur as a clinical manifestation or induced experimentally in animals. The extensor reflexes are exaggerated leading to rigid extension of the limbs accompanied by hyperreflexia and opisthotonus. This condition is usually caused by lesions which occur in the region of the brainstem that lies between the red nuclei and the vestibular nuclei. In contrast, decorticate rigidity is characterized by flexion of the elbows and wrists with extension of the legs and feet. The causative lesion for this condition is located above the red nuclei and usually consists of diffuse cerebral damage. (From Adams et al., Principles of Neurology, 6th ed, p358)Parasympatholytics: Agents that inhibit the actions of the parasympathetic nervous system. The major group of drugs used therapeutically for this purpose is the MUSCARINIC ANTAGONISTS.Escin: Pentacyclic triterpene saponins, biosynthesized from protoaescigenin and barringtogenol, occurring in the seeds of AESCULUS. It inhibits edema formation and decreases vascular fragility.Muscle Strength: The amount of force generated by MUSCLE CONTRACTION. Muscle strength can be measured during isometric, isotonic, or isokinetic contraction, either manually or using a device such as a MUSCLE STRENGTH DYNAMOMETER.Muscle Strength Dynamometer: A device that measures MUSCLE STRENGTH during muscle contraction, such as gripping, pushing, and pulling. It is used to evaluate the health status of muscle in sports medicine or physical therapy.Vasodilator Agents: Drugs used to cause dilation of the blood vessels.Basilar Artery: The artery formed by the union of the right and left vertebral arteries; it runs from the lower to the upper border of the pons, where it bifurcates into the two posterior cerebral arteries.

Inhibitory innervation of cat sphincter of Oddi. (1/15397)

1 Electrical stimulation with trains of 0.1-0.2 ms pulses of the cat isolated sphincter of Oddi inhibited the spontaneous contractile activity and lowered base-line tension considerably. A contraction usually followed the period of stimulation. 2 These inhibitory effects were prevented by tetrodotoxin 0.1-0.5 mug/ml but were not reduced by hexamethonilm, morphine, or blockade of alpha- or beta-adrenoreceptors of cholinoceptors with phenoxy-benzamine propranolol or atropine, respectively. 3 Adenosine-5'-triphosphate (ATP) and adenosine-5'-diphosphate (ADP) inhibited the spontaneous sphincter activity and caused relaxation thus mimicking the effects of the C-terminal octapeptide of cholecystokinin (C8-CCK), isoprenaline and prostaglandin E1 and E2. 4 ATP alone (greater than 100 mug/ml) or ATP (greater than 10 mug/ml) plus dipyridamole (1 mug/ml), relaxed the sphincter to the same degrees as did the field stimulation. 5 In sphincter maximally contracted by acetylcholine, the effect of stimulation was more marked than that recorded in uncontracted preparations. 6 The present findings suggest that the sphincter of Oddi receives inhibitory nerves that are neither cholinergic nor adrenergic.  (+info)

Single blind, randomised controlled trial of pelvic floor exercises, electrical stimulation, vaginal cones, and no treatment in management of genuine stress incontinence in women. (2/15397)

OBJECTIVE: To compare the effect of pelvic floor exercises, electrical stimulation, vaginal cones, and no treatment for genuine stress incontinence. DESIGN: Stratified, single blind, randomised controlled trial. SETTING: Multicentre. PARTICIPANTS: 107 women with clinically and urodynamically proved genuine stress incontinence. Mean (range) age was 49.5 (24-70) years, and mean (range) duration of symptoms 10.8 (1-45) years. INTERVENTIONS: Pelvic floor exercise (n=25) comprised 8-12 contractions 3 times a day and exercise in groups with skilled physical therapists once a week. The electrical stimulation group (n=25) used vaginal intermittent stimulation with the MS 106 Twin at 50 Hz 30 minutes a day. The vaginal cones group (n=27) used cones for 20 minutes a day. The untreated control group (n=30) was offered the use of a continence guard. Muscle strength was measured by vaginal squeeze pressure once a month. MAIN OUTCOME MEASURES: Pad test with standardised bladder volume, and self report of severity. RESULTS: Improvement in muscle strength was significantly greater (P=0.03) after pelvic floor exercises (11.0 cm H2O (95% confidence interval 7.7 to 14.3) before v 19.2 cm H2O (15.3 to 23.1) after) than either electrical stimulation (14.8 cm H2O (10. 9 to 18.7) v 18.6 cm H2O (13.3 to 23.9)) or vaginal cones (11.8 cm H2O (8.5 to 15.1) v 15.4 cm H2O (11.1 to 19.7)). Reduction in leakage on pad test was greater in the exercise group (-30.2 g; -43. 3 to 16.9) than in the electrical stimulation group (-7.4 g; -20.9 to 6.1) and the vaginal cones group (-14.7 g; -27.6 to -1.8). On completion of the trial one participant in the control group, 14 in the pelvic floor exercise group, three in the electrical stimulation group, and two in the vaginal cones group no longer considered themselves as having a problem. CONCLUSION: Training of the pelvic floor muscles is superior to electrical stimulation and vaginal cones in the treatment of genuine stress incontinence.  (+info)

Cerebellar Purkinje cell simple spike discharge encodes movement velocity in primates during visuomotor arm tracking. (3/15397)

Pathophysiological, lesion, and electrophysiological studies suggest that the cerebellar cortex is important for controlling the direction and speed of movement. The relationship of cerebellar Purkinje cell discharge to the control of arm movement parameters, however, remains unclear. The goal of this study was to examine how movement direction and speed and their interaction-velocity-modulate Purkinje cell simple spike discharge in an arm movement task in which direction and speed were independently controlled. The simple spike discharge of 154 Purkinje cells was recorded in two monkeys during the performance of two visuomotor tasks that required the animals to track targets that moved in one of eight directions and at one of four speeds. Single-parameter regression analyses revealed that a large proportion of cells had discharge modulation related to movement direction and speed. Most cells with significant directional tuning, however, were modulated at one speed, and most cells with speed-related discharge were modulated along one direction; this suggested that the patterns of simple spike discharge were not adequately described by single-parameter models. Therefore, a regression surface was fitted to the data, which showed that the discharge could be tuned to specific direction-speed combinations (preferred velocities). The overall variability in simple spike discharge was well described by the surface model, and the velocities corresponding to maximal and minimal discharge rates were distributed uniformly throughout the workspace. Simple spike discharge therefore appears to integrate information about both the direction and speed of arm movements, thereby encoding movement velocity.  (+info)

Spinal cord-evoked potentials and muscle responses evoked by transcranial magnetic stimulation in 10 awake human subjects. (4/15397)

Transcranial magnetic stimulation (TCMS) causes leg muscle contractions, but the neural structures in the brain that are activated by TCMS and their relationship to these leg muscle responses are not clearly understood. To elucidate this, we concomitantly recorded leg muscle responses and thoracic spinal cord-evoked potentials (SCEPs) after TCMS for the first time in 10 awake, neurologically intact human subjects. In this report we provide evidence of direct and indirect activation of corticospinal neurons after TCMS. In three subjects, SCEP threshold (T) stimulus intensities recruited both the D wave (direct activation of corticospinal neurons) and the first I wave (I1, indirect activation of corticospinal neurons). In one subject, the D, I1, and I2 waves were recruited simultaneously, and in another subject, the I1 and I2 waves were recruited simultaneously. In the remaining five subjects, only the I1 wave was recruited first. More waves were recruited as the stimulus intensity increased. The presence of D and I waves in all subjects at low stimulus intensities verified that TCMS directly and indirectly activated corticospinal neurons supplying the lower extremities. Leg muscle responses were usually contingent on the SCEP containing at least four waves (D, I1, I2, and I3).  (+info)

99mTc-labeled vasoactive intestinal peptide receptor agonist: functional studies. (5/15397)

Vasoactive intestinal peptide (VIP) is a naturally occurring 28-amino acid peptide with a wide range of biological activities. Recent reports suggest that VIP receptors are expressed on a variety of malignant tumor cells and that the receptor density is higher than for somatostatin. Our aims were to label VIP with 99mTc--a generator-produced, inexpensive radionuclide that possesses ideal characteristics for scintigraphic imaging--and to evaluate 99mTc-VIP for bioactivity and its ability to detect experimental tumors. METHODS: VIP28 was modified at the carboxy terminus by the addition of four amino acids that provided an N4 configuration for a strong chelation of 99mTc. To eliminate steric hindrance, 4-aminobutyric acid (Aba) was used as a spacer. VIP28 was labeled with 1251, which served as a control. Biological activity of the modified VIP28 agonist (TP3654) was examined in vitro using a cell-binding assay and an opossum internal anal sphincter (IAS) smooth muscle relaxivity assay. Tissue distribution studies were performed at 4 and 24 h after injection, and receptor-blocking assays were also performed in nude mice bearing human colorectal cancer LS174T. Blood clearance was examined in normal Sprague-Dawley rats. RESULTS: The yield of 99mTc-TP3654 was quantitative, and the yields of 125I-VIP and 1251-TP3654 were >90%. All in vitro data strongly suggested that the biological activity of 99mTc-TP3654 agonist was equivalent to that of VIP28. As the time after injection increased, radioactivity in all tissues decreased, except in the receptor-enriched tumor (P = 0.84) and in the lungs (P = 0.78). The tumor uptake (0.23 percentage injected dose per gram of tissue [%ID/g]) was several-fold higher than 125I-VIP (0.06 %ID/g) at 24 h after injection in the similar system. In mice treated with unlabeled VIP or TP3654, the uptake of 99mTc-TP3654 decreased in all VIP receptor-rich tissues except the kidneys. The blood clearance was biphasic; the alpha half-time was 5 min and the beta half-time was approximately 120 min. CONCLUSION: VIP28 was modified and successfully labeled with 99mTc. The results of all in vitro examinations indicated that the biological activity of TP3654 was equivalent to that of native VIP28 and tumor binding was receptor specific.  (+info)

Uterine peristalsis during the follicular phase of the menstrual cycle: effects of oestrogen, antioestrogen and oxytocin. (6/15397)

Uterine peristalsis, directing sustained and rapid sperm transport from the external cervical os or the cervical crypts to the isthmic part of the tube ipsilateral to the dominant follicle, changes in direction and frequency during the menstrual cycle, with lowest activity during menstruation and highest activity at mid cycle. It was therefore suggested that uterine peristalsis is under the control of the dominant follicle with the additional involvement of oxytocin. To test this hypothesis, vaginal sonography of uterine peristalsis was performed in the early, mid and late proliferative phases, respectively, of cycles of women treated with oestradiol valerate and with human menopausal gonadotrophin following pituitary downregulation, with clomiphene citrate and with intravenous oxytocin, respectively. Administration of oestradiol valerate resulted in oestradiol serum concentrations comparable with the normal cycle with a simulation of the normal frequency of peristaltic contractions. Elevated oestradiol concentrations and bolus injections of oxytocin resulted in a significant increase in the frequency of peristaltic contractions in the early and mid follicular phases, respectively. Chlomiphene tended, though insignificantly so, to suppress the frequency of peristaltic waves in the presence of elevated oestradiol concentrations. In the late follicular phase of the cycle extremely elevated oestradiol concentrations as well as the injection of oxytocin resulted only in an insignificant further increase of peristaltic frequency. In the normal cycles, as well as during extremely elevated oestradiol concentrations and following oxytocin administration, the peristaltic contractions were always confined to the subendometrial layer of the muscular wall. The results and the review of literature indicate that uterine peristalsis during the follicular phase of the menstrual cycle is controlled by oestradiol released from the dominant follicle with the probable involvement of oxytocin, which is presumably stimulated together with its receptor within the endometrial-subendometrial unit and therefore acting in an autocrine/paracrine fashion. Since unphysiological stimulation with oestradiol and oxytocin did not significantly increase the frequency of uterine peristalsis in the late follicular phase of the cycle it is assumed that normal preovulatory frequency of uterine peristalsis is at a level which cannot be significantly surpassed due to phenomena of refractoriness of the system.  (+info)

Adrenoreceptors of the guinea-pig urinary bladder. (7/15397)

1 Adrenaline, noradrenaline and isoprenaline (5 mug/ml) did not affect the resting tone of the isolated urinary bladder of the guinea-pig. 2 The catecholamines (1-2 mug/ml) inhibited neuronally evoked contractions at various stimulation frequencies; the inhibition was maximum at 2 Hz and minimum at 50 Hz. Isoprenaline produced maximum inhibition. 3 Propranolol (0.5 mug/ml) completely blocked the catecholamine-induced inhibition at all the frequencies employed. The concentration-response curves of isoprenaline at 2, 10 and 50 Hz were characteristically shifted by propranolol (50 ng/ml). Phenoxybenzamine (0.2 mug/ml) was totally ineffective. 4 In some experiments adrenaline significantly raised the tone of the bladder exposed to propranolol; this effect could be blocked by phenoxybenzamine. 5 Acetylcholine-induced bladder contractions were inhibited by adrenaline (2 mug/ml); the inhibition was completely blocked by propranolol (0.5 mug/ml). 6 The results indicate the presence of an inhibitory beta-adrenoceptor and suggest the possibility of an excitatory alpha-adrenoceptor in guinea-pig urinary bladder.  (+info)

The cat lung strip as an in vitro preparation of peripheral airways: a comparison of beta-adrenoceptor agonists, autacoids and anaphylactic challenge on the lung strip and trachea. (8/15397)

1 A new in vitro preparation, the isolated lung strip of the cat, is described for investigating the direct effect of drugs on the smooth muscle of the peripheral airways of the lung. The preparation comprises a thin strip of lung parenchyma which can be mounted in a conventional organ bath for isometric tension recording. Its pharmacological responses have been characterized and compared with the isolated tracheal preparation of the cat. 2 The lung strip exhibited an intrinsic tone which was relaxed by catecholamines, aminophylline and flufenamate. It was contracted strongly by histamine, prostaglandin F2alpha, acetylcholine, compound 48/80, potassium depolarizing solution and alternating current field stimulation. In contrast, the cat trachea was unresponsive to histamine and prostaglandin F2alpha and did not exhibit an intrinsic tone. 3 (-)-Isoprenaline and (-)-adrenaline were much more potent in relaxing the lung strip than the trachea. The potency order of relaxation responses to isoprenaline, adrenaline and (+/-)-noradrenaline in the lung strip was isoprenaline greater than adrenaline greater than noradrenaline but in the trachea was isoprenaline greater than noradrenaline greater than or equal to adrenaline. 4 beta2-Adrenoceptor selective agonists salbutamol and terbutaline were more potent in the lung strip than the trachea, suggesting beta2-adrenoceptors predominated in the lung strip. Propranolol was equipotent in inhibiting isoprenaline relexations of the lung strip and trachea, whereas practolol was much less effective in inhibiting lung strip than trachea, further supporting a predominance of beta2-adrenoceptors in lung strip and beta1-adrenoceptors in trachea. 5 Strong Schultz-Dale type contractions were elicited in both lung strips and trachea by Ascaris lumbricoides antigen in actively sensitized cats. The initial phase of the contractile response of the lung strip following challenge was shown to be due to histamine release and was absent in the trachea. The delayed phase of the contraction which took several minutes to develop in both the mepyramine-treated lung strip and trachea was not due to prostaglandins E1, F2alpha or bradykinin, the probable mediator being slow reacting substance of anaphylaxis (SRS-A). 6 It is concluded that the isolated lung strip of the cat is useful as an in vitro model for investigating the effect of drugs on the smooth muscle of the peripheral airways of the lungs.  (+info)

TY - JOUR. T1 - Brain functional connectivity is different during voluntary concentric and eccentric muscle contraction. AU - Yao, Wan X.. AU - Jiang, Zhiguo. AU - Li, Jinqi. AU - Jiang, Changhao. AU - Franlin, Crystal G.. AU - Lancaster, Jack L. AU - Huang, Yufei. AU - Yue, Guang H.. PY - 2016/11/15. Y1 - 2016/11/15. N2 - Previous studies report greater activation in the cortical motor network in controlling eccentric contraction (EC) than concentric contraction (CC) of human skeletal muscles despite lower activation level of the muscle associated with EC. It is unknown, however, whether the strength of functional coupling between the primary motor cortex (M1) and other involved areas in the brain differs as voluntary movements are controlled by a network of regions in the primary, secondary and association cortices. Examining fMRI-based functional connectivity (FC) offers an opportunity to measure strength of such coupling. To address the question, we examined functional MRI (fMRI) data ...
During an eccentric contraction, the muscle elongates while under tension due to an opposing force being greater than the force generated by the muscle.[1] Rather than working to pull a joint in the direction of the muscle contraction, the muscle acts to decelerate the joint at the end of a movement or otherwise control the repositioning of a load. This can occur involuntarily (when attempting to move a weight too heavy for the muscle to lift) or voluntarily (when the muscle is smoothing out a movement). Over the short-term, strength training involving both eccentric and concentric contractions appear to increase muscular strength more than training with concentric contractions alone.[2] During an eccentric contraction of the biceps muscle, the elbow starts the movement while bent and then straightens as the hand moves away from the shoulder. During an eccentric contraction of the triceps muscle, the elbow starts the movement straight and then bends as the hand moves towards the shoulder. ...
The foundations for this topic can be found in the previous 4 articles in the series. Building off the understanding of viscoelastic tissues that are sensitive to the rate at which force is applied, we will examine training strategies designed to maximize muscle stimulation while avoiding injury. There are 3 types of muscle contraction:. Concentric - the muscle is shortening while contracting (the positive rep). Isometric - the muscle does not change length while contracting. Eccentric - the muscle is lengthening while contracting (the negative rep). It is widely misstated, and then repeated by others, that eccentric contractions produce more force than isometric contractions which produce more force than concentric contractions. This is not true. The force generated by muscle contraction is determined by the equation for torque reviewed in the last article, independent of the shortening or lengthening during contraction (minus a subtle detail - hysteresis - which is beyond the scope of our ...
Definition of concentric contraction in the Financial Dictionary - by Free online English dictionary and encyclopedia. What is concentric contraction? Meaning of concentric contraction as a finance term. What does concentric contraction mean in finance?
Static muscular contraction in anesthetized animals has been firmly established to reflexly increase arterial pressure. Although group III and IV muscle afferents are known to be responsible for this reflex pressor response, there is no evidence that the stimulation of muscle mechanoreceptors, many of which are supplied by group III fibers, plays a role in causing this contraction-induced reflex effect. To provide this evidence, we recorded renal sympathetic nerve activity in chloralose-anesthetized cats while contracting the triceps surae muscles. We found that static contraction tripled renal nerve activity within three seconds of its onset, an increase that was abolished by cutting the L6 and S2 dorsal roots. On average, the contraction-induced increase in renal nerve activity was observed 0.8 +/- 0.1 seconds after the onset of this maneuver. In addition, intermittent tetanic contractions synchronized renal nerve discharge so that a burst of activity was evoked by each contraction. A ...
Definition of concentric muscle contraction in the Financial Dictionary - by Free online English dictionary and encyclopedia. What is concentric muscle contraction? Meaning of concentric muscle contraction as a finance term. What does concentric muscle contraction mean in finance?
Eccentric exercise or resistance training is currently being used as a form of rehabilitation for sport injuries, but also as an alternative form of exercise for the elderly, those affected by neurological disorders, COPD, cardiopulmonary disorders, and cancer.[6] Muscle loss is a big problem faced by the people afflicted with the above disorders and many cannot participate in rigorous exercise protocols. Eccentric muscle contractions produce high forces with low-energy cost. According to Hortobágyi due to these properties eccentric exercise has the greatest potential for muscle strengthening.[7] To strengthen muscle the external force must exceed the muscle while it lengthens.[8] The definition of eccentric contraction is almost the exact definition of muscle strengthening. Perceived muscle damage: There is a stipulation regarding eccentric contractions in that they actually cause muscle damage and injury. Eccentric contraction may result in delayed onset muscle soreness however; the ...
The main new findings from this study of afferent arterioles from normal C57BL/6 mice were that increasing the PP from 40 to 80 mm Hg caused a myogenic contraction accompanied by an increase in ROS signal whether detected by dihydroethidium or tempo-9AC. The fluorescent ROS signal was predominately O2 · −, because it was reduced by incubation with PEG-SOD or Tempol but not with PEG-CAT and was upstream from Ca2+ because it persisted in Ca2+-free medium. Incubation of vessels with Tempol, PEG-SOD, apocynin, or DPI reduced basal and myogenic tone, whereas PEG-CAT was not effective, indicating that the responses were enhanced by O2 · − generated from NADPH oxidase. The moderation of myogenic contractions by Tempol was prevented by preincubation with PEG-SOD but was preserved by preincubation with PEG-CAT. H2O2 caused contractions at concentrations ,50 μmol/L but inhibited myogenic responses at 25 μmol/L. l- NAME increased basal tone but did not affect pressure-induced ROS generation. ...
Looking for Isotonic Muscle Contraction? Find out information about Isotonic Muscle Contraction. contraction of a muscle at unchanging tension, expressed in a decrease in its length and an increase in its transverse section. Purely isotonic muscle... Explanation of Isotonic Muscle Contraction
It is intriguing how the mechanics of molecular motors is regulated to perform the mechanical work in living systems. In sharp contrast to the conventional wisdom, recent experiments indicated that motor force maintains ∼6 pN upon a wide range of filament loads during skeletal muscle contraction at the steady state. Here we find that this rather precise regulation which takes place in an essentially chaotic system, can be due to that a "working" motor is arrested in a transitional state when the motor force is ∼6 pN. Our analysis suggests that the motor force can be self-regulated through chemomechanical coupling, and motor force homeostasis is a built-in feature at the level of a single motor, which provides insights to understanding the coordinated function of multiple molecular motors existing in various physiological processes. With a coupled stochastic-elastic numerical framework, the kinetic model for a Actin-myosin-ATP cycle constructed in this work might pave the way to decently ...
The muscles can perform the same function in a specific segment (muscles of fast and slow contraction), and at the same time be antagonistic in relation to muscular action (flexors or extensors). The present research aimed to study the morphology, frequency and metabolism of fiber types and the contractile characteristics of extensor and flexors muscles of rabbit. We studied muscles anterior tibialis (AT), flexor digitorum supeficialis (FDS), extensor digitorum longus (EDL) and posterior tibialis (PT). The muscles were submitted to the techniques HE, NADH-TR and myofibrillar ATPase. In EDL and PT extensor muscles, the frequencies of red (SO + FOG) and white fibers (FG) were 68.77% and 31.23% versus 58.87% and 41.13%, respectively. In the AT and FDS flexor muscles, these frequencies were 75.14% and 24.86% versus 73.89% and 26.11%, respectively. In extensor muscles, the percentage of slow contraction fibers was 8.05% in EDL and 9.74% in PT, and in fast contraction, 91.95% in EDL and 90.26% in PT. ...
When a muscle contraction is required, it receives a message from the brain for voluntary contractions and from the spinal cord for reflex contractions. This message, called a nerve impulse or action potential, is carried along motoneurons to the muscle. It would not be practical for all the fibers in a given muscle to contract every time the motoneuron discharged an action potential. Therefore, before the motoneuron reaches the target muscle, it divides into many separate branches that independently activate groups of muscle fibers. These groupings are referred to as motor units. The number of fibers per motor unit depends on the specific muscle. A small muscle used for intricate movements will have less than 100 fibers per motor unit and less than 100 motor units in total. A large muscle used for weight-bearing and propulsion will have several thousand fibers per motor unit and several hundred motor units ...
Weight training is all about throwing the weights about right? Even the best bodybuilder of all time in my opinion, Arnie, named his video Pumping Iron which says a lot. Yet I find myself tearing my hair out when I watch most people in the gym lift weights, to be blunt their form is pretty poor. To be more specific, I am referring to their repetition tempo during each phase of the muscle contraction. Today I wanted to educate you a little on muscle contractions and the importance of utilising them.ConcentricConcentric muscle contractions occur when the muscle shortens, so a doing a bicep curl is a perfect example. Many people will perform this part of the repetition with very little control of the weight and instead employ a great deal of momentum to shift the resistance from A to B. This is a great way to go if building a super-sized ego is the main goal, but if building quality lean muscle tissue is something you are interested in I suggest you listen.During a concentric muscle contraction by
Before I start talking about using different contraction types in training and the benefits they will have, first I must explain to anyone who doesnt know about the 3 different types of contraction. Keeping it nice and basic, there are 3 different ways that your muscle can contract in order to move a part of your body. Concentric - a concentric contraction is where the muscle shortens in length causing your bodypart to move. For example when you concentrically contract your bicep, it shortens and your arm bends (flexes). Most people who will train will be primarily focused on this type of contraction as it is the one that moves the weight against the resistance. For example it is the concentric contraction that pushes the bar off your chest to lockout on a bench press. Eccentric - an eccentric contraction is the lengthening of the muscle. This occurs when you lower the weight under control. Its the opposite movement to the concentric contraction but it isnt the antagonistic muscle that
During a stretch- shortening cycle (SSC), muscle force attained during concentric contractions (shortening phase) is potentiated by the preceding eccentric contractions (lengthening phase). The purpose of this study was to examine the influence of joint angular velocity on force potentiation induced by SSC (SSC effect). Twelve healthy men (age, 24.2 ± 3.2 years; height, 1.73 ± 0.05 m; body mass, 68.1 ± 11.0 kg) participated in this study. Ankle joint angle was passively moved by a dynamometer, with range of motion from dorsiflexion (DF) 15° to plantarflexion (PF) 15°. Muscle contractions were evoked by tetanic electrical stimulation. Joint angular velocity of concentric contraction was set at 30°/s and 150°/s. Magnitude of SSC effect was calculated as the ratio of joint torque obtained by concentric contraction with preliminary eccentric contraction trial relative to that obtained by concentric contraction without preliminary eccentric contraction trial. As a result, magnitude of SSC effect
Below are two different but similar descriptions of muscle contraction that explain the processes involved in notification, contraction, and relaxation.. The following steps are involved in muscle contraction:. (1) The sequence of events leading to contraction is initiated somewhere in the central nervous system, either as voluntary activity from the brain or as reflex activity from the spinal cord.. (2) A motor neuron in the ventral horn of the spinal cord is activated, and an action potential passes outward in a ventral root of the spinal cord.. (3) The axon branches to supply a number of muscle fibers called a motor unit, and the action potential is conveyed to a motor end plate on each muscle fiber.. (4) At the motor end plate, the action potential causes the release of packets or quanta of acetylcholine into the synaptic clefts on the surface of the muscle fiber.. (5) Acetylcholine causes the electrical resting potential under the motor end plate to change, and this then initiates an action ...
Ever wonder how a muscle contracts to create movement? Weve come up with a simple guide to help you understand muscle contraction.
1. The effect of pH on excitation-contraction coupling in skeletal muscle of the toad was examined using a skinned fibre preparation which gives ready access to the intracellular environment while still allowing stimulation of Ca2+ release by the normal voltage-sensor mechanism. 2. In each fibre, depolarization-induced responses (produced by changing the ions in the bathing solution) were examined first at pH 7.1, and then at another pH between 6.1 and 8.0. At all pH levels examined, the first depolarization elicited a large response which was slightly greater (pH 7.6 and 8.0) or smaller (pH 6.6 and 6.1) than that at pH 7.1. The size of the first depolarization-induced response varied with pH in almost exactly the same manner as did the maximum Ca(2+)-activated response. The duration of the depolarization-induced response at all other pH levels was longer than at pH 7.1. 3. Repeated depolarizations (30 s or more apart) produced similar responses at pH 7.1, but at all other pH levels examined the ...
I have to do a literature review on a topic involving neurophysiology. So I chose to pick one about the force-velocity relationship of muscle contractions. The relationship shows that as muscle velocity increases, muscle force decreases. I was wondering if anybody has any research articles that show the opposite: That as velocity increases muscle force increases as well. I have searched to no avail. I appreciate any help.
Types of Contraction. All types of strength are a result of individual muscle fibres contracting, a muscle fibre contracts fully or not at all, the number of muscle fibres that contract simultaneously define the amount of force a muscle can produce and whether that muscle can overcome, maintain, or slowly lower the load its working against.. If the force generated by the muscle fibres is greater than the load, then the entire muscle length will shorten and the load will move, this is called a Concentric Contraction.. When the load is greater than the force produced by the muscle fibres the muscle will lengthen, this is called an Eccentric Contraction, even though the muscle as a whole is lengthening, individual fibres are still contracting trying to resist the load.. Concentric/Eccentric contractions are collectively known as Dynamic contractions. When the force exerted by the fibres is equal to the load no movement takes place, this is called an Isometric Contraction. This of special interest ...
Several studies reported that exercising one limb produces gains in motor output in the same muscle of the un-exercised, contralateral limb. This phenomenon is called cross education. There are also data to suggest that muscle and brain activation are different when muscles shorten and lengthen and that the amount of cross education may be also different according to the type of muscle contraction. This thesis is an initial effort in the form of a cross sectional study to shed light on the mechanism of cross education. This project examines the hypothesis that spinal excitability varies in the resting limb according to the type and intensity of muscle contraction in the contralateral limb. The purpose of this study was to compare spinal excitability in the right wrist flexors during and after concentric and eccentric contraction of the left wrist flexors at an intensity of 100% and 60% of the maximum. Ten healthy right-handed subjects (5 females, 5 males, mean age 21 [plus/minus] 3 years) ...
Researchers in the Department of Human Health and Nutritional Sciences have gained new insights into the fundamental properties that govern muscle activity and influence our day-to-day movement.. Prof. Geoffrey Power and his research group have discovered a unique interplay between our nervous system and a phenomenon that occurs during muscle contraction known as torque depression.. Muscle contraction is what drives human movement. For example, the movement associated with taking a drink involves contraction and shortening of the bicep muscles. This contraction generates a force called torque that causes the forearm to rotate at the elbow towards your mouth, and allows you to enjoy your morning coffee. But not all muscle contractions are created equal. During contractions where the muscle does not shorten, such as holding a travel mug at waist-level between sips, the muscle generates more torque compared to a muscle that had to shorten to match the same position. The lower amount of torque ...
A new wearable microscope enables in vivo monitoring of individual muscle fiber contractions in live humans, a feat that has not been possible despite our longstanding physiological understanding of how muscles contract. According to the report in the December 16 Neuron online, researchers led by senior authors Scott Delp and Mark Schnitzer at Stanford University in Palo Alto, California, have developed a microscope by connecting an infrared light source to a fine needle containing miniaturized optics that is inserted into the muscle. The device can distinguish fast and slow twitch muscles, stimulate muscle contractions, and track changes in properties of the individual contractile units of skeletal muscles, or sarcomeres, that occur due to injury or disease. This compact, portable device could fit on a bedside pushcart, and the researchers hope to ultimately develop it into a clinically useful device for diagnosing neuromuscular diseases and monitoring their progression in human ...
Dear Readers, Audrey is 56 years old and has been experiencing increasing episodes of muscle contractions in her calves and even in her feet at times. The contractions can last from a few seconds to more than 15 minutes. They occur mainly...
THE CONTRACTION AND Relaxation OF CARDIAC FIBERS Through contraction of your coronary heart muscle fiber inside the ventricles, blood enters the arteries that depart the center for the other organs of the physique. After the contraction, the ventricles then take it easy to reduced force and make place for blood from atria. The decreased tension is definitely the diastolic stress from peace when the systolic strain occurs with the contraction of your hearts ventricular muscular tissues.. The center muscle fibers are interconnected and glimpse more such as skeletal muscle. The muscle fiber has both of those the skinny and thick filaments having a tiny sarcoplasmic reticulum. The calcium ions originate from inside and outdoors the cells thus earning the contraction of your cardiac muscle mass fiber actin-regulated . The thin and thick filaments slide using an enhance in calcium ions brought on via the motion potential within the membrane a result of the activation of ATPase with the myosin. Bulk ...
Purpose: To determine the effects of concentric and eccentric muscle contractions on IL-6 signaling and its possible downstream regulation of HSP-72 expression in human skeletal muscle, and whether contraction-induced ...
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The OF studied show marked differences in contractile activity. Whilst CF contract matrix by 55% within the first 24h, the same number of TF only contract it by 10%. Whilst contraction by CF quickly reaches a plateau, TF generate sustained contraction. Final matrix contraction is the same. SF only contract matrix at higher cell density. CF generate the greatest force; TF generate 2/3 less, and SF hardly any. Three main factors determine contraction efficiency: cell volume (CF,TF,SF), cell protrusive and retractile activity (dynamic index, DI), and efficient binding to matrix fibrils. DI mirrors force generation. ML9 reduces DI and force generation. Ilomastat has a modest effect on DI and force, but dramatically inhibit matrix contraction, indicating that additional mechanisms are involved. ...
In a previous communication by one of us (G. B. (1)) it was shown that graded contractions and relaxations of natural form can be obtained in the diaphragm and in skeletal nerve muscle preparation by manipulating a faradic induction apparatus in a special manner. Briefly, this manipulation consists in imparting a smooth to-and-fro movement to the secondary coil of the apparatus, the movement taking place between the points of just maximal and just minimal stimulation. These to-and-fro movements cause certain changes of amplitude in the stimulating current, and the various patterns thus produced are faithfully repeated in the contractions of the experimental muscle, provided the changes are kept within the above-mentioned limiting points. An attempt has been made in the present research to obtain reciprocal contraction of antagonistic muscles by an extension of the above method. In the working-out of the new method of excitation, and in its application to double nerve-muscle preparations, the ...
Approach and Results-Real-time polymerase chain reaction, immunohistochemistry, and Western analyses supported the synthesis and expression of chemerin in perivascular adipose tissue, whereas the primary chemerin receptor ChemR23 was expressed both in the tunica media and endothelial layer. The ChemR23 agonist chemerin-9 caused receptor, concentration-dependent contraction in the isolated rat thoracic aorta, superior mesenteric artery, and mesenteric resistance artery, and contraction was significantly amplified (more than 100%) when nitric oxide synthase was inhibited and the endothelial cell mechanically removed or tone was placed on the arteries. The novel ChemR23 antagonist CCX832 inhibited phenylephrine-induced and prostaglandin F2α-induced contraction (+perivascular adipose tissue), suggesting that endogenous chemerin contributes to contraction. Arteries from animals with dysfunctional endothelium (obese or hypertensive) demonstrated a pronounced contraction to chemerin-9. Finally, ...
DALLAS - Researchers at UT Southwestern Medical Center have identified a previously unrecognized small protein in cells of the human heart that plays a key role in heart muscle contraction. The protein is made from an RNA that was previously believed to be a blank or non-coding RNA, suggesting there may be many other small "non-coding" segments that play important biological roles. Significantly, the findings published today in Science offer a potential new target for developing therapeutics to boost the strength of cardiac muscle contractions in patients with heart failure, a chronic condition in which the heart pumps too weakly to supply adequate oxygen to the body. The new protein, which the researchers have named dwarf open reading frame (DWORF), comprises just 34 amino acids, making it the third smallest protein known to be encoded in the mouse genome. By comparison, an average-sized protein is 10 times larger, including about 350 amino acids. DWORF is also encoded in the human genome. The ...
where Λ is the ratio of muscle length to the "optimal" length at which maximal isometric tension is produced, and α(Λ) is a function numerically equal to the ratio of the tetanic isometric force to its maximum value. The single dimensionless constant in this relation, B, can be calculated from model parameters characterizing muscle dynamics at the optimum length, and has a value near unity for frog sartorius at 0°C. The predicted behavior is shown to agree reasonably well with experimental measurements of heat production and phosphocreatine (PCr) hydrolysis. The model relates the isometric energy rates to PCr hydrolysis in (1) cross-bridge interactions, and (2) calcium pumping into the sarcoplasmic reticulum.. ...
There are a number of factors that increase the risk of a quadriceps strain. For example, high forces across the muscle-tendon units combined with eccentric contraction can lead to strain injury. Excessive passive stretching or activation of a maximally stretched muscle can also cause strains. Muscle fatigue has also been shown to play a role in acute muscle injury(3). This may account for the observation of increased injury risk during the pre-season (when fitness levels tend to be lower, leading to the earlier onset of fatigue). However, of the four bellies, the RF is most frequently strained(4-8). There are a number of factors behind the increased vulnerability of RF; as well as crossing two joints, it contains a high percentage of explosive type-II fibres and also has a complex musculotendinous architecture, all of which are known to increase injury risk(9,10).. As noted in the NCAA study above, indirect trauma occurs for the most part as a result of eccentric contractions(4,11). This can ...
Although the contraction of each muscle cell is all-or non, it is obvious that body movements are not. Sometimes they are forceful, other times slight. This is easily accounted for by realizing that body movements are brought about by whole muscles (groups of muscle cells), not by single cell acting alone. Increasing the force of movement may simply be a matter of recruiting more and more cells into cooperative action. However, there are also more subtle means for changing the performance of individual cells.. The strength or, more precisely, the force a muscle is capable of exerting depends on its length. For each muscle cell, there is an optimum length or range of lengths where the contractile force is strongest. This is easily explained by the sliding fillament theory. The strength of contraction depends on the number of cross bridges that can make contact with actin fillaments. When the muscle is too long, few cross bridges can make contact, and contraction is weak. When the muscle is too ...
Looking for eccentric, contraction muscle? Find out information about eccentric, contraction muscle. the contractile tissue that effects the movement of and within the body. Muscle tissue in the higher animals is classified as striated, smooth, or cardiac,... Explanation of eccentric, contraction muscle
DOMS is the main reason youre slow to get out of bed the next day. Theodore Hough first described this phenomenon in 1902, stating that DOMS is "fundamentally the result of ruptures within the muscle.". Dont fret; its not as bad as it sounds. However, his statement still rings mostly true to this day. Research has found that eccentric muscle contractions cause tiny tears to the connective tissue and units of muscle known as myofilaments, which collectively make up a muscle fiber. It is this structural damage to the muscle that causes the pain and tenderness associated with DOMS.. Soreness usually starts around 24 hours after activity and peaks between 48 and 72 hours. From there, it usually dissipates and is gone completely 5 to 7 days after activity. The more strenuous the activity, the longer the soreness will last. Youre more likely to suffer from DOMS if you have taken a long break from exercise and are just getting started back, or, similarly, if you are engaging in physical activity ...
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Inactivation of excitation-contraction coupling was examined in extensor digitorum longus (EDL) and soleus muscle fibers from rats injected daily with tri-iodothyronine (T3, 150 micrograms/kg) for 10-14 d. Steady-state activation and inactivation curves for contraction were obtained from measurements of peak potassium contracture tension at different surface membrane potentials. The experiments tested the hypothesis that noninactivating tension is a "window" tension caused by the overlap of the activation and inactivation curves. Changes in the amplitude and voltage dependence of noninactivating tension should be predicted by the changes in the activation and inactivation curves, if noninactivating tension arises from their overlap. After T3 treatment, the area of overlap increased in EDL fibers and decreased in soleus fibers and the overlap region was shifted to more negative potentials in both muscles. Noninactivating tension also appeared at more negative membrane potentials after T3 ...
Only a few words and phrases about rhythmic contraction and comfort of cardiovascular system lean muscle in helpful coming up with Rhythmic contraction and
We explain Muscle Contractions: Macro View with video tutorials and quizzes, using our Many Ways(TM) approach from multiple teachers.|p|This lesson will give an overview of how a specific muscle contracts to allow movement in the body. |/p|
How to Stop Muscle Twitches. Muscle twitches are caused by small contractions in either a part of a muscle or a whole muscle. They can occur in any muscle in the body but often occur in the limbs, eyelids, or diaphragm. They are typically...
In 1855 Guillaume Duchenne, the father of electrotherapy, announced that alternating was superior to direct current for electrotherapeutic triggering of muscle contractions. What he called the warming affect of direct currents irritated the skin, since, at voltage strengths needed for muscle contractions, they cause the skin to blister (at the anode) and pit (at the cathode). Furthermore, with DC each contraction requiring the current to be stopped and restarted. Moreover alternating current could produce strong muscle contractions regardless of the condition of the muscle, whereas DC-induced contractions were strong if the muscle was strong, and weak if the muscle was weak. Since that time almost all rehabilitation involving muscle contraction has been done with a symmetrical twin-phase wave. In the 1940s, however, the US War Department, investigating the application of electrical stimulation not just to retard and prevent atrophy but to restore muscle mass and strength, employed what was ...
Wound contraction is a basic mechanism for wound closure that can be lifesaving. Yet, wound contraction can also produce considerable deformity and misery in conditions as diverse as burn scar...
Muscle Contraction And Movement In Animals, Class 6. Muscle is the fibrous tissue in the body that has the ability to contract. The movement of body parts in human beings is brought about by the alternate contraction and stretching of the muscles attached to the movable bones of the skeleton.
In the reflex a muscle contracts when the - The Knee Jerk Reflex - Indiana Public Media. Sports nutritionals. Muscle Advance Weight Gainer with 810 Calories, 52g Protein, 94g Carbs Per-Serving.
Contraction and relaxing of cardiac muscle mass materials Release The cardiac cardiovascular system muscle materials acquire and take it easy from the move full potential brought on by the movements of calcium supplement and sodium ions. Contraction Contraction of cardiac muscle fibres starts off by your excitation of muscle mass fibres.grademiners.com/case-study-help Excitation of muscle group fibers is operated by central nervous system at neuromuscular junctions utilizing neurotransmitter. Behavior likely journeys about the sarcolemma. Calcium mineral ions are introduced from SR and combine to troponin which transforms size and shape and myosin binding sites are totally exposed Salt ions influx from extracellular space, reasons advantageous information setting up of voltage-gated sodium ion channels; membrane layer possibility rather quickly depolarizes (-90 to 30 mV); salt ion routes complete around 3 ms of launching. Depolarization results in discharge of calcium supplement ions from ...
Based on the framework of sliding-filament theory and on the cross-bridges dynamics, a mathematical model for the simulation of the force response and length change of individual myofibril is presented. The myofibril is modeled as a group of segments placed in series, each segment represents a half-sarcomere with active and elastic properties. A multiple-state cross-bridge formalism relates the half Sarcomere force to the chemical kinetics of ATP hydrolysis. The corresponding system of nonlinear nonlocal partial differential equations of the model is analyzed. A numerical approach is introduced and some numerical tests are performed. The proposed in-silico model enables the study of biologically relevant process in the muscle contraction process, also in the case of muscular diseases, with reasonable computational effort. ...
BioAssay record AID 510178 submitted by ChEMBL: Reduction of acetylcholine-induced muscle contraction in frog abdominal straight muscle.
A concentric muscle contraction is a type of muscle activation that increases tension on a muscle as it shortens. Learn how it works in the gym.
This is anatomy and physiology lecture 7 of the Muscular System sections. In this video we take a look at the types of muscle contractions: isometric, isotonic, concentric, and eccentric. We also cover the relationship muscles have with each other, specifically the agonist, synergists, antagonist, and fixator ...
... high levels of epinephrine causes smooth muscle relaxation in the airways but causes contraction of the smooth muscle that ... Arnall DA, Marker JC, Conlee RK, Winder WW (June 1986). "Effect of infusing epinephrine on liver and muscle glycogenolysis ... stimulates glycogenolysis in the liver and muscle,[37] and stimulates glycolysis and inhibits insulin-mediated glycogenesis in ... It plays an important role in the fight-or-flight response by increasing blood flow to muscles, output of the heart, pupil ...
Muscle contraction. References[edit]. *^ a b c d e f Hong, TingTing; Shaw, Robin M. (2017-01-01). "Cardiac T-Tubule ... excitation-contraction coupling). When contraction of a muscle is needed, stimulation from a nerve or an adjacent muscle cell ... They are found in ventricular muscle cells in most species, and in atrial muscle cells from large mammals.[4] In cardiac muscle ... Excitation-contraction coupling[edit]. See also: Excitation-contraction coupling. T-tubules are an important link in the chain ...
Cardiac muscle relaxation. *Smooth muscle contraction. *cardioprotective in cardiac ischemia. *inhibition of neutrophil ...
Mechanical work in muscles. Muscle contraction model. Founding biophysics. Hill equation (biochemistry). ... After publication he learned that German physiologist had already reported on heat and muscle contraction and he went to ... In 1926 he was invited to deliver the Royal Institution Christmas Lecture on Nerves and Muscles: How We Feel and Move. ... Hill made many exacting measurements of the heat released when skeletal muscles contract and relax. A key finding was that heat ...
vascular permeability; vascular smooth muscle contraction; allergy. antagonists of CYSLTR1 used in asthma as well as other ... vascular permeability; vascular smooth muscle contraction; allergy. antagonists of CYSLTR1 used in asthma as well as other ... platelet aggregation, vascular smooth muscle contraction. PGI2 analogs used to treat vascular disorders like pulmonary ...
The muscles then contract through the sliding filament mechanism, causing shortening of sarcomeres and muscle contraction. ... "Thromboxane A2-induced contraction of rat caudal arterial smooth muscle involves activation of Ca2+ entry and Ca2+ ... Webb RC (2003). "Smooth muscle contraction and relaxation". Adv Physiol Educ. 27 (1-4): 201-6. doi:10.1152/advan.00025.2003. ... When these cells are depolarized, the L-type calcium channels open as in smooth muscle. In skeletal muscle, the actual opening ...
The muscles then contract through the sliding filament mechanism, causing shortening of sarcomeres and muscle contraction. ... Muscle physiology[edit]. When a smooth muscle cell is depolarized, it causes opening of the voltage-gated (L-type) calcium ... When these cells are depolarized, the L-type calcium channels open as in smooth muscle. In skeletal muscle, the actual opening ... Skeletal muscle, smooth muscle, bone (osteoblasts), ventricular myocytes** (responsible for prolonged action potential in ...
For example, it regulates the contraction of muscles, nerve conduction, and the clotting of blood. As a result, intra- and ... in contraction of all muscle cell types; as cofactors in many enzymes; and in fertilization. Calcium ions outside cells are ... Symptoms include anorexia, nausea, vomiting, memory loss, confusion, muscle weakness, increased urination, dehydration, and ...
Muscle contractionEdit. The nervous system and musculoskeletal system control the majority of mammalian motility. ... Skeletal muscle is the type of muscle you use to move, e.g. the bicep and triceps move the lower arm. Skeletal muscles are ... As the muscles run out of ATP, the muscle fibres become permanently contracted and lock solid. This produces a stiffening ... Muscles give the ability for voluntary movement, and involuntary movement as in muscle spasms and reflexes). At the level of ...
... 's role in muscle contractionEdit. The helical F-actin filament found in muscles also contains a tropomyosin molecule, a ... Outline of a muscle contractionEdit. In muscle cells, actomyosin myofibrils make up much of the cytoplasmic material. These ... Both actin and myosin are involved in muscle contraction and relaxation and they make up 90% of muscle protein.[136] The ... In metazoan muscle cells, to be the scaffold on which myosin proteins generate force to support muscle contraction. ...
For concentric muscle contractions, see Muscle contraction § Concentric contraction. For other uses, see Concentric ( ...
Muscle contraction[edit]. Main article: Muscle contraction. When contracting, thin and thick filaments slide with respect to ... The contraction of all the sarcomeres results in the contraction of the whole muscle fiber. This contraction of the myocyte is ... Isometric contractions are skeletal muscle contractions that do not cause movement of the muscle. However, isotonic ... This in turn causes the muscle cell to relax.[20] Kinds of contraction[edit]. There are four main different types of muscle ...
Kardel, Troels (1990). "Niels Stensen's geometrical theory of muscle contraction (1667): A reappraisal". Journal of ... Like Vincenzo Viviani, Steno proposed a geometrical model of muscles to show that a contracting muscle changes its shape but ... In Florence Steno focused on the muscular system and the nature of muscle contraction. He became a member of Accademia del ... and determined that it was an ordinary muscle[25][26] and not the center of warmth as Galenus and Descartes believed.[27] Steno ...
The contraction of the muscles must be willed." A few sources, such as the Model Penal Code, provide a more thorough treatment ...
Main article: Muscle contraction. Multiple myosin II molecules generate force in skeletal muscle through a power stroke ... Myosin II (also known as conventional myosin) is the myosin type responsible for producing muscle contraction in muscle cells. ... oʊ-/[1][2]) are a superfamily of motor proteins best known for their roles in muscle contraction and in a wide range of other ... The MLC20 is also known as the regulatory light chain and actively participates in muscle contraction.[15] ...
positive regulation of uterine smooth muscle contraction. Sources: Amigo / QuickGO. 直系同源体. ... positive regulation of hindgut contraction. · negative regulation of gastric acid secretion. · ...
This misfiring may result from impaired inhibitory mechanisms during muscle contraction.[1] When the brain tells a given muscle ... that affects a muscle or group of muscles in a specific part of the body, causing involuntary muscular contractions and ... Leisner, David (2007). "Curing Focal Dystonia or How to Play the Guitar with Large Muscles". Guitar Review. 133: 10-15.. ... sensory cortex may prevent normal sensorimotor feedback and so contribute to the observed co-contraction of antagonist muscle ...
Actions on the neuromuscular junction will result in prolonged muscle contraction.. *The effects of neostigmine on ... To reverse the effect of non-depolarising muscle relaxants. *To treat neuropsychiatric symptoms of diseases such as Alzheimer's ...
The force of the contraction obtained depends on the state in which the muscles fibres find themselves. In the case of muscle ... The contraction is not increased if the stimulus strength is further raised. Stronger stimuli bring more muscle fibres into ... It was first established by the American physiologist Henry Pickering Bowditch in 1871 for the contraction of heart muscle. ... contraction of the amphibian skeletal muscle fibre". The Journal of Physiology. 38 (2-3): 113-33. doi:10.1113/jphysiol.1909. ...
Muscle energy techniques address somatic dysfunction through stretching and muscle contraction. For example, if a person is ... This resistance against the patient's motion allows for isometric contraction of the patient's muscle. Once the patient relaxes ... The repetition of alternating cycles of contraction and subsequent relaxation help the treated muscle improve its range of ... Muscle energy[edit]. Main article: Muscle energy technique. ... severe muscle spasms or strains, severe osteoporosis, severe ...
Tonic seizures produce constant contractions of the muscles.[18] The person may turn blue if breathing is impaired.[18] ... Jerking activity may start in a specific muscle group and spread to surrounding muscle groups-known as a Jacksonian march.[16] ... A cry may be heard due to contraction of the chest muscles.[18] The limbs then begin to shake in unison.[18] After the shaking ... Atonic seizures involve the loss of muscle activity for greater than one second.[16] This typically occurs bilaterally (on both ...
Eccentric contraction may result in delayed onset muscle soreness however; the contraction itself does not cause muscle damage ... Muscle injury[edit]. Eccentric contractions are a frequent cause of muscle injury when engaging in unaccustomed exercise. But a ... Perceived muscle damage: There is a stipulation regarding eccentric contractions in that they actually cause muscle damage and ... Eccentric contraction and oxygen consumption: Oxygen consumption is needed for muscles to work properly. Eccentric muscle ...
... it typically causes contraction of smooth muscle, such as that observed during bronchoconstriction and bladder voiding.[21] ... piloerectile muscles of the body hairs, and the skeletal muscle arterioles do not use adrenaline/noradrenaline. ... They are located in the smooth muscles of the blood vessels, as well as in the lungs. Because the M3 receptor is Gq-coupled and ... They also moderately reduce contractile forces of the atrial cardiac muscle, and reduce conduction velocity of the ...
This leads to free intracellular calcium and causes muscle contraction and hyperthermia. Dantrolene inhibits calcium release ... The resulting muscle relaxation allows heat dissipation. There is little risk to dantrolene administration. Since dantrolene ...
There are co-contractions of agonist and antagonist muscles. Spasms usually last for minutes and can recur over hours. Attacks ... Using electromyography, they noted that motor-unit firing suggested that voluntary muscle contractions were occurring in their ... They observed "persistent tonic contraction reflected in constant firing, even at rest" after providing patients with muscle ... which become rigid and stiff because the lumbar and abdominal muscles engage in constant contractions. Initially, stiffness ...
... and he thought there was reason to believe that the sudden contraction of muscle is produced by its combination with other ... and is further formed by the combination of these two sets of particles in muscle during violent exertion. In effect, therefore ... combustible (salino-sulphureous) particles in the body; hence the heart, being a muscle, ceases to beat when respiration is ...
Discover what can cause muscle cramps and how you can prevent them. ... Muscle cramps are involuntary contractions of one or more of your muscles. ... What are muscle cramps?. Muscle spasms are strong, painful, involuntary contractions of one or more of your muscles; a ... home > health > muscles joints > muscle pain > how to prevent muscle cramps How to prevent muscle cramps. What causes muscle ...
Treating muscle cramps requires a multi-tiered approach that includes lifestyle changes, dietary changes and nutritional ... What is a Muscle Cramp?. A muscle cramp is defined as the sudden, involuntary contraction of one or more of the muscles. This ... Critical Electrolytes for Muscle Spasms. Potassium. Potassium is an important factor in the function of the muscles and nerves ... contraction typically renders the muscle useless and can be quite painful. A hard lump of muscle tissue may also develop ...
Besides, apigenin inhibited actin polymerization, which underlines muscle contraction and cell migration. The results suggest ... QINGXIN, Liu et al. Apigenin inhibits cell migration through MAPK pathways in human bladder smooth muscle cells. Biocell [ ... To assess possible effects of apigenin on migration of bladder smooth muscle (SM) cell, we isolated SM cells from peri-cancer ... showed that overexpression of active human MEKK1 by adenoviruses infection induced migration of human bladder smooth muscle ( ...
This is because muscle contraction is influenced by many variables, not just sodium. ... Sodium, along with other electrolytes, controls muscle contractions by triggering nerve impulses. When sodium levels drop, the ... "Ive heard that my muscle cramps on longer runs can be caused by low salt levels? Is this true and why does that happen?" ... The cause and solution for your muscle cramps is going to be a combination of these variables. The fun part of my job is ...
Covers causes like strained muscles, dehydration, and needing more potassium or calcium in your body. Covers treatment and ... Discusses muscle cramps, also known as charley horses. ... A muscle cramp is a strong, painful contraction or tightening ... What causes muscle cramps?. The cause of muscle cramps isnt always known. Muscle cramps may be brought on by many conditions ... Stretch and massage the muscle.. *Take a warm shower or bath to relax the muscle. A heating pad placed on the muscle can also ...
Create healthcare diagrams like this example called Muscle Contraction in minutes with SmartDraw. SmartDraw includes 1000s of ... Muscle Contraction. Cross-sections of the muscle, showing muscle fibers and their microscopic anatomy.. Biceps while arm is ... Muscle Contraction. Create healthcare diagrams like this example called Muscle Contraction in minutes with SmartDraw. SmartDraw ... The muscle in a. relaxed state.. The muscle is contracted.. LifeART Collection Images Copyright © 1989-2001 by Lippincott ...
... a group of rare muscle contraction disorders characterized by pain and fatigue. ... blocks channels for sodium ions in muscle cells, leading to a reduction in muscle contraction rate and stiffness. ... Cite this: CHMP Backs Antiarrhythmic for Muscle-Contraction Disorders - Medscape - Oct 19, 2018. ... a group of inherited muscle contraction disorders.. This would be the first treatment authorized EU-wide for this rare ...
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Muscle Contraction : Biochemical Aspects of Sportive Practice was designed to promote the association... ... Muscle Contraction: Android app (10+ downloads) → The software ... Muscle Contraction "Muscle Contraction : Biochemical Aspects of Sportive Practice" is an e-book! ... The software Muscle Contraction : Biochemical Aspects of Sportive Practice was designed to promote the association between ...
The active ingredient appears to be nitrate, which somehow reduces the oxygen cost of muscle contractions. How does this happen ... and even the contractile properties of the muscle fibers themselves. ... Why, then, was there no effect on voluntary muscle contractions? When you use electricity to make a muscle twitch, youre just ... Beets Boost Muscle Contraction. Nitrate in your food makes muscle fibers twitch harder. ...
... been possible for the first time to record equatorial and meridional X-ray reflexions from striated muscle during contraction ... FOR some time X-ray diffraction techniques have been used to study living muscle in the resting state1-4. Using a modified ... Memories of early work on muscle contraction and regulation in the 1950s and 1960s *Hugh E. Huxley ... ELLIOTT, G., LOWY, J. & MILLMAN, B. X-ray Diffraction from Living Striated Muscle during Contraction. Nature 206, 1357-1358 ( ...
In contrast, during isometric and eccentric contraction, when is small, then. In this connection it is of interest to consider ... 3. Poorly Understood Phenomena in Muscle Contraction. Because muscle contraction is due to the action of a very large ensemble ... muscle fiber) and in parallel over the muscle fiber cross-section. During muscle contraction, globular myosin motor domains ( ... Further, eccentric contraction, when the muscle is stretched during activity, is associated with work done on the muscle rather ...
... in heart muscle releases a large amount of Ca2+ in response to a small amount of trigger Ca2+ by the mechanism of the Ca2+- ... Regulation of Contraction in Heart Muscle. A Ca2+ Gradient Model for the Ca2+-Induced Ca2+-Release of the Sarcoplasmic ... This interprets the effects of beat frequency and external [Ca2+] on twitch contractions in intact heart muscle. The present Ca ... Tameyasu T. (1998) Regulation of Contraction in Heart Muscle. In: Sugi H., Pollack G.H. (eds) Mechanisms of Work Production and ...
... Our heart and skeletal muscles contain intricately organized cells that generate the ... Structural changes in muscle during contraction; interference microscopy of living muscle fibers. Nature. 173:971-973. Huxley, ... in powering contraction. To account for their observations, both groups surmised that muscle contraction was not caused by A- ... Muscle Contraction and Sliding Filaments. For Biophysics Week, members of the Early Careers Committee have written short ...
... this is a comprehensive account of the theory of muscle contraction, in parallel with exciting experimental discoveries of the ... The first book to provide a unified description of the mathematics of muscle contraction, ... Understanding the molecular mechanism of muscle contraction started with the discovery that striated muscle is composed of ... The Sliding-Filament Theory of Muscle Contraction. Authors. * David Smith Copyright. 2018. Publisher. Springer International ...
Optically controlled contraction of photosensitive skeletal muscle cells.. Asano T1, Ishizua T, Yawo H. ... It also induced a twitch-like contraction in a concurrent manner. A contraction pattern was thus made with a given pattern of ... As the skeletal muscle cell is an efficient force transducer, it has been incorporated in bio-microdevices using electrical ... This technique would have many applications in the bioengineering field, such as wireless drive of muscle-powered actuators/ ...
Muscle Contraction - Download as Powerpoint Presentation (.ppt), PDF File (.pdf), Text File (.txt) or view presentation slides ... no more than 10 kg of muscle (,1/3 the total muscle mass) can be fully active at any one time. . the blood flow in 1 kg of ... the muscle must rid itself of metabolic products such as H+. Muscle work therefore requires drastic cardiovascular and ... Excessive physical exercise causes muscle soreness and stiffness. which leads to muscle swelling and pain. . The underlying ...
Contraction of Cardiac & Smooth Muscle • Although significant differences exist, the basic mechanism in both muscle types ... Types of Skeletal Muscle Fiber • 1. Red muscle fibers • a. Slow twitch, fatigue resistant • - Splits ATP slowly; rich blood ... Contraction of Skeletal Muscle • 1. A nerve signal triggers the release of • acetylcholine into neuromuscular synapse. • 2. ... 3. Most skeletal muscles in the body have a mixture of all three fiber types in various • proportions depending on the muscle ...
Nitric oxide, reactive oxygen species, and skeletal muscle contraction.. Reid MB1. ... the processes whereby endogenous ROS modulate contraction of unfatigued muscle, and 3) the site(s) of action and reversibility ... whereby NO and ROS regulate contraction. This review article provides a personal perspective on the processes regulated by NO ... modulate contractile function of respiratory and limb skeletal muscle. The intracellular processes regulated by NO and ROS ...
... Oleg S. Matusovsky. ,1. ,. 2 Olga Mayans. ,3 and Danuta ... showed that during muscle contraction force and calcium transients are not changing in parallel and that a change in steady- ... Molecular Mechanism of Muscle Contraction: New Perspectives and Ideas. View this Special Issue. ... pointed out the poorly understood aspects of striated muscle contraction and, in particular, the relationship between the force ...
Muscle power output and the steady rate of contraction are linked by modulating a single parameter, a viscosity coefficient. ... Muscle operation is characterized by working strokes of much shorter length and much quicker than in the classical model. As a ... as the tendency of these proteins to form geometrically ordered structures provide a link between water and muscle contraction ... to the stiffness of muscle structures and to the viscosity of the sliding of the thin over the thick filaments. ...
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Cardiac Muscle resembles skeletal muscle in its structure and in regulation of actin-myosin interactions and muscle contraction ... Smooth Muscle[edit]. Actin and myosin are much less organized in smooth muscle when compared to skeletal muscle. Smooth muscle ... Skeletal Muscle[edit]. A motor nerve action potential spreads down transverse tubules and then passes to the sarcoplasmic ... Troponin/Tropomyosin Regulate Contraction[edit]. Myosin and Actin invitro binds and hydrolyzes ATP, even in the absence of Ca2+ ...
Triclosan impairs excitation-contraction coupling and Ca2+ dynamics in striated muscle Message Subject (Your Name) has sent you ... Triclosan impairs excitation-contraction coupling and Ca2+ dynamics in striated muscle. Gennady Cherednichenko, Rui Zhang, ... 1982) Slow inward calcium currents have no obvious role in muscle excitation-contraction coupling. Nature 298:292-294. ... 1995) Raised intracellular [Ca2+] abolishes excitation-contraction coupling in skeletal muscle fibres of rat and toad. J ...
... in a chemical reaction with water provides energy for skeletal muscles to contract. Since the amount of... ... How do your muscle cells produce ATP during rapid exercise?. A: Muscle cells produce ATP anaerobically during periods of rapid ... such as muscle contraction, transmission of nerve... Full Answer , Filed Under: * Tennis ... metabolic pathways that generate new ATP must be activated for continued muscle contraction. These pathways are either ...
  • Regulating the activity level and eating a balanced diet with plenty of water supports effective functioning and eliminates many symptoms of muscle cramping. (earthclinic.com)
  • Symptoms Blockages can restrict blood flow to the muscles , causing muscle cramps , tightness or weakness, especially during activity. (symptoma.com)
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