Biomaterial Database

Activation of cat motor units by paired stimuli at short intervals. 1987

G Horcholle-Bossavit, and L Jami, and J Petit, and J J Scott

Laboratoire de Neurophysiologie, Collège de France, Paris.

1. In adult cats, paired stimulations at short intervals were applied in ventral root filaments to single motor axons innervating the peroneus tertius muscle. Paired impulses were recorded from the muscle nerve simultaneously with the electrical and mechanical responses of the muscle portion of the motor unit (muscle unit). The interstimulus interval was gradually reduced in order to determine the minimum compatible with a full activation of the muscle unit by the second impulse. 2. For motor units of all physiological types, this minimum stimulus interval was the shortest interval allowing initiation and conduction of two impulses in the axon, that is, the absolute refractory period for conduction. Its duration ranged between 0.58 and 0.88 ms, displaying no correlation with the axonal conduction velocity. 3. The amount of tension enhancement produced by paired stimulations at the shortest interval varied with the type of the motor unit: it was largest for fast-fatigable units, intermediate for fast-resistant units and smallest for slow units. 4. Paired impulses elicited by paired stimulations at the shortest possible interval arrived near the muscle at a longer interval because the second impulse was conducted at a slower velocity. The minimum interval between arrival of impulses at the muscle depended on conduction velocity and on conduction distance. 5. In motor axons to peroneus tertius, paired impulses leaving the spinal cord at a mean interval of 0.78 ms arrived near the muscle separated by a mean interval of 1.90 ms. Since such an interval always allowed full activation of the muscle unit by the second impulse, this interval is longer than the refractory period of motor units in this muscle.

UI	MeSH Term	Description	Entries
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
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
D006614	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)	Hindlimbs
D000200	Action Potentials	Abrupt changes in the membrane potential that sweep along the CELL MEMBRANE of excitable cells in response to excitation stimuli.	Spike Potentials,Nerve Impulses,Action Potential,Impulse, Nerve,Impulses, Nerve,Nerve Impulse,Potential, Action,Potential, Spike,Potentials, Action,Potentials, Spike,Spike Potential
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
D001369	Axons	Nerve fibers that are capable of rapidly conducting impulses away from the neuron cell body.	Axon
D013126	Spinal Nerve Roots	Paired bundles of NERVE FIBERS entering and leaving the SPINAL CORD at each segment. The dorsal and ventral nerve roots join to form the mixed segmental spinal nerves. The dorsal roots are generally afferent, formed by the central projections of the spinal (dorsal root) ganglia sensory cells, and the ventral roots are efferent, comprising the axons of spinal motor and PREGANGLIONIC AUTONOMIC FIBERS.	Dorsal Roots,Spinal Roots,Ventral Roots,Dorsal Root,Nerve Root, Spinal,Nerve Roots, Spinal,Root, Dorsal,Root, Spinal,Root, Spinal Nerve,Root, Ventral,Roots, Dorsal,Roots, Spinal,Roots, Spinal Nerve,Roots, Ventral,Spinal Nerve Root,Spinal Root,Ventral Root