Changes in discharge rate of cat hamstring fusimotor neurones during fatiguing contractions of triceps surae muscles

doi:10.1016/0006-8993(92)90057-G

Brain Research

Volume 579, Issue 2, 8 May 1992, Pages 246-252

https://doi.org/10.1016/0006-8993(92)90057-G Get rights and content

Abstract

Changes in the discharge rate of fusimotor neurones to hamstring muscles during long-lasting, fatiguing, contractions of the triceps surae muscles were studied in decerebrate cats. Discharges of fusimotor neurones were recorded from the nerve filaments. Muscle contractions were elicited by electrical stimulation of the muscle nerves applied until the muscle tension fell to about 30% of its initial value. Early and late changes could be recognized in fusimotor discharge rate. The early changes, at the onset of muscle contraction, occurred in 9 out of 22 neurones and varied in both sign and duration among the cells. The late change, encountered in 16 fusimotor neurones, was an increase in discharge rate developing towards the end of the muscle contraction and outlasting it. When the contracting triceps muscle was made ischaemic the late increase in discharge rate developed earlier, as did the muscle tension fall and started to subside after the arterial clamp was removed. After severing the muscle nerves their stimulation provoked either no changes or a slight sustained decrease in fusimotor discharge rate. It is supposed that the late increase in discharge rate of fusimotor neurones to hamstring muscles appears due to reflex excitation by discharges in group III and IV afferent fibres from the triceps muscle provoked and/or enhanced by metabolic products liberated during its fatiguing contraction. The possibility is raised that the excitation is elicited primarily by the discharges from chemosensitive afferent fibres. Its functional role in muscle fatigue is discussed.

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Changes in discharge rate of cat hamstring fusimotor neurones during fatiguing contractions of triceps surae muscles

Abstract

Exp. Neurol.

Brain Res.

Neuroscience

The relative dependence of the activity of Renshaw cells on recurrent pathways during contraction of the triceps muscle

Pflügers Arch.

Action on gamma motoneurones elicited by electrical stimulation of group II muscle afferent fibres in the hindlimb of the cat

J. Physiol.

Action on gamma motoneurones elicited by electrical stimulation of group III muscle afferent fibres in the hind limb of the cat

J. Physiol.

Recurrent actions on gamma motoneurones mediated via large and small ventral root fibres in the cat

J. Physiol.

Continuous conduction in demyelinated mammalian nerve fibres

Nature

Electro-mechanic failures and lactate production during fatigue

Eur. J. Appl. Physiol.

Supraspinal control of interneurones mediating spinal reflexes

J. Physiol.

Recurrent inhibition of fusimotor neurones exhibiting background discharge in the decerebrate and the spinal cat

J. Physiol.

Closely coupled excitation of γ-motoneurones by group III muscle afferents with low mechanical threshold in the cat

J. Physiol.

Effects of muscle fatigue on mechanically sensitive afferents of slow conduction velocity in the cat triceps surae

J. Neurophysiol.

Intrinsic membrane properties causing a bistable behaviour of α-motoneurones

Exp. Brain Res.

Relation of function to diameter in afferent fibres of muscle nerves

J. Gen. Physiol.

Persisting changes in sensory and motor activity of a muscle following its reflex activation

Pflügers Arch.