Biomaterial Database

Changes in fusimotor discharge rate provoked by isotonic fatiguing muscle contractions in decerebrate cats. 1995

M Ljubisavljević, and R Anastasijević, and D Trifunjagić

Institute for Medical Research, Beograd, Yugoslavia.

Changes in discharge rate of 26 fusimotor neurones to medial gastrocnemius muscle were studied during isotonic fatiguing contractions of lateral gastrocnemius and soleus muscles in decerebrate cats. Muscle contractions were elicited by either continuous or repetitive electrical stimulation of the muscle nerves. The muscles were considered to be fatigued when, against a load equal to one third of the tension developed at the onset of an isometric contraction, i.e. to the tension indicating isometrically-induced fatigue, they returned to the length at which the isometric contraction was elicited. At the onset of muscle contraction an increase in discharge rate, lasting for 5-220 s, occurred in all except one of the neurones. In 73% of the units a late increase developed in addition in parallel with muscle fatigue outlasting the contraction for 5-180 s. All but one of the remaining neurones exhibited a short lasting burst of spike discharges coincident with the end of contraction. Enhancement of the late increase by muscle ischaemia indicates contribution of chemosensitive small-diameter muscle afferents, while the short lasting burst is supposed to be elicited rather by the mechanosensitive units sensitized by metabolic products liberated during contraction and/or fatigue. Differences of the fusimotor reflex responses to isotonic vs. isometric contraction and/or fatigue and their possible functional role are discussed.

UI	MeSH Term	Description	Entries
D007551	Isotonic Contraction	Muscle contraction with negligible change in the force of contraction but shortening of the distance between the origin and insertion.	Contraction, Isotonic,Contractions, Isotonic,Isotonic Contractions
D009047	Motor Neurons, Gamma	Motor neurons which activate the contractile regions of intrafusal SKELETAL MUSCLE FIBERS, thus adjusting the sensitivity of the MUSCLE SPINDLES to stretch. Gamma motor neurons may be "static" or "dynamic" according to which aspect of responsiveness (or which fiber types) they regulate. The alpha and gamma motor neurons are often activated together (alpha gamma coactivation) which allows the spindles to contribute to the control of movement trajectories despite changes in muscle length.	Neurons, Fusimotor,Neurons, Gamma Motor,Gamma Motorneurons,Motor Neurons, Gamma-Efferent,Fusimotor Neuron,Fusimotor Neurons,Gamma Motor Neuron,Gamma Motor Neurons,Gamma Motorneuron,Gamma-Efferent Motor Neuron,Gamma-Efferent Motor Neurons,Motor Neuron, Gamma,Motor Neuron, Gamma-Efferent,Motor Neurons, Gamma Efferent,Motorneuron, Gamma,Motorneurons, Gamma,Neuron, Fusimotor,Neuron, Gamma Motor,Neuron, Gamma-Efferent Motor,Neurons, Gamma-Efferent Motor
D009119	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.	Inotropism,Muscular Contraction,Contraction, Muscle,Contraction, Muscular,Contractions, Muscle,Contractions, Muscular,Inotropisms,Muscle Contractions,Muscular Contractions
D002415	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)	Felis catus,Felis domesticus,Domestic Cats,Felis domestica,Felis sylvestris catus,Cat,Cat, Domestic,Cats, Domestic,Domestic Cat
D003655	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)	Decerebrate Posturing,Decorticate Rigidity,Decorticate State,Rigidity, Decerebrate,Rigidity, Decorticate,Decerebrate Posturings,Decerebrate Rigidity,Decerebrate States,Decorticate Rigidities,Decorticate States,Posturing, Decerebrate,Posturings, Decerebrate,Rigidities, Decorticate,State, Decerebrate,States, Decerebrate
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D013997	Time Factors	Elements of limited time intervals, contributing to particular results or situations.	Time Series,Factor, Time,Time Factor
D018482	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.	Anterior Tibial Muscle,Gastrocnemius Muscle,Muscle, Voluntary,Plantaris Muscle,Skeletal Muscle,Soleus Muscle,Muscle, Anterior Tibial,Muscle, Gastrocnemius,Muscle, Plantaris,Muscle, Soleus,Muscles, Skeletal,Muscles, Voluntary,Skeletal Muscles,Tibial Muscle, Anterior,Voluntary Muscle,Voluntary Muscles
D018763	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.	Fatigue, Muscle,Muscular Fatigue,Fatigue, Muscular