Biomaterial Database

Physiological types and histochemical profiles in motor units of the cat gastrocnemius. 1973

R E Burke, and D N Levine, and P Tsairis, and F E Zajac

1. A variety of physiological properties of single motor units have been studied in the gastrocnemius muscle (primarily in the medial head) of pentobarbitone-anaesthetized cats. Intracellular stimulation of individual motoneurones ensured functional isolation of the muscle units innervated by them.2. A system for muscle unit classification was developed using a combination of two physiological properties. Almost all of the units studied could be classified into one of three major types, including two groups with relatively short twitch contraction times (types FF and FR, which were differentiable from one another on the basis of sensitivity to fatigue) and one group with relatively long contraction times (type S, which were extremely resistant to fatigue and were differentiable from FF and FR units on the basis of the shape of unfused tetani). Post-tetanic potentiation of twitch responses was observed in all three muscle unit types. The distributions of axonal conduction velocities for motoneurones innervating FF and FR muscle units were essentially the same, while conduction velocities for motoneurones innervating type S units were, in general, slower.3. Histochemical profiles of muscle units representative of each of the physiological classes present in the gastrocnemius pool were determined using a method of glycogen depletion for muscle unit identification. Each of the physiological categories of muscle units exhibited a corresponding unique set of muscle fibre staining reactions, or histochemical profile. Within each physiological type, all of the units examined had the same histochemical profile. The results generally support the hypothesis that the histochemical characteristics of muscle fibres are meaningfully related to the physiological properties of the same fibres. However, certain limitations in the detailed application of the hypothesis were also apparent.4. Systematic assessment of the histochemical profiles of relatively large numbers of fibres belonging to single muscle units provided strong support for the hypothesis that all of the muscle fibres innervated by a single alpha-motoneurone are histochemically identical.

UI	MeSH Term	Description	Entries
D007770	L-Lactate Dehydrogenase	A tetrameric enzyme that, along with the coenzyme NAD+, catalyzes the interconversion of LACTATE and PYRUVATE. In vertebrates, genes for three different subunits (LDH-A, LDH-B and LDH-C) exist.	Lactate Dehydrogenase,Dehydrogenase, L-Lactate,Dehydrogenase, Lactate,L Lactate Dehydrogenase
D007866	Leg	The inferior part of the lower extremity between the KNEE and the ANKLE.	Legs
D009046	Motor Neurons	Neurons which activate MUSCLE CELLS.	Neurons, Motor,Alpha Motorneurons,Motoneurons,Motor Neurons, Alpha,Neurons, Alpha Motor,Alpha Motor Neuron,Alpha Motor Neurons,Alpha Motorneuron,Motoneuron,Motor Neuron,Motor Neuron, Alpha,Motorneuron, Alpha,Motorneurons, Alpha,Neuron, Alpha Motor,Neuron, 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
D009132	Muscles	Contractile tissue that produces movement in animals.	Muscle Tissue,Muscle,Muscle Tissues,Tissue, Muscle,Tissues, Muscle
D009247	NADH, NADPH Oxidoreductases	A group of oxidoreductases that act on NADH or NADPH. In general, enzymes using NADH or NADPH to reduce a substrate are classified according to the reverse reaction, in which NAD+ or NADP+ is formally regarded as an acceptor. This subclass includes only those enzymes in which some other redox carrier is the acceptor. (Enzyme Nomenclature, 1992, p100) EC 1.6.	Oxidoreductases, NADH, NADPH,NADPH Oxidoreductases NADH,Oxidoreductases NADH, NADPH
D009431	Neural Conduction	The propagation of the NERVE IMPULSE along the nerve away from the site of an excitation stimulus.	Nerve Conduction,Conduction, Nerve,Conduction, Neural,Conductions, Nerve,Conductions, Neural,Nerve Conductions,Neural Conductions
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
D004558	Electric Stimulation	Use of electric potential or currents to elicit biological responses.	Stimulation, Electric,Electrical Stimulation,Electric Stimulations,Electrical Stimulations,Stimulation, Electrical,Stimulations, Electric,Stimulations, Electrical
D004594	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.