Sympathetic and noradrenaline effects on C-fibre transmission: single-unit analysis.

Single afferent unmyelinated fibres were dissected from the otherwise intact sural nerve in anesthetized rabbits. The sympathetic trunk could be stimulated via electrodes implanted through the abdomen. The response in single C fibres was elicited by electrical stimulation in the cutaneous innervation area of the fibre. Sympathetic stimulation (8 Hz, 1 ms pulses, 5 mA for 60 s) increased the latency in all tested C fibres (2.0% +/- 0.8%, mean +/- SD, n = 17). In 48% of the units the amplitude of the action potential decreased (26.4% +/- 12.3%) during sympathetic stimulation. Infusion of noradrenaline (5 micrograms min-1) increased (7.7% +/- 4.1%) the latency in all units and increased (36.9% +/- 29.8%) the amplitude of 25% of the units. The effects of sympathetic stimulation and noradrenaline infusion were blocked by pre-treatment with phentolamine (3 mg kg-1 i.v.). The results suggest that catecholamines change the membrane properties of unmyelinated fibres.

[1]  S. Andersson,et al.  Effects of sympathetic stimulation on C-fibre responses in rabbit. , 1989, Acta physiologica Scandinavica.

[2]  L. Dahlin,et al.  Effects of nerve compression or ischaemia on conduction properties of myelinated and non-myelinated nerve fibres. An experimental study in the rabbit common peroneal nerve. , 1989, Acta physiologica Scandinavica.

[3]  B. Lynn,et al.  Effects of sympathetic stimulation on mechanoreceptive and nociceptive afferent units from the rabbit pinna , 1986, Brain Research.

[4]  W. Roberts.  A hypothesis on the physiological basis for causalgia and related pains , 1986, Pain.

[5]  W. Roberts,et al.  Sympathetic activation of unmyelinated mechanoreceptors in cat skin , 1985, Brain Research.

[6]  W. Kollmann,et al.  The involvement of the sympathetic nervous system in pain. Possible neuronal mechanisms. , 1984, Arzneimittel-Forschung.

[7]  W. Bradley,et al.  Unmyelinated axon subpopulations in the rat peripheral nervous system , 1983, Neurology.

[8]  W. Bradley,et al.  Sympathetic postganglionic unmyelinated axons in the rat peripheral nervous system , 1983, Neurology.

[9]  M. Devor.  Nerve pathophysiology and mechanisms of pain in causalgia. , 1983, Journal of the autonomic nervous system.

[10]  R. Klein,et al.  Opioid peptides and noradrenaline co-exist in large dense-cored vesicles from sympathetic nerve , 1982, Neuroscience.

[11]  M. Devor,et al.  Activation of myelinated afferents ending in a neuroma by stimulation of the sympathetic supply in the rat , 1981, Neuroscience Letters.

[12]  M. Devor,et al.  Ectopic adrenergic sensitivity in damaged peripheral nerve axons in the rat , 1981, Experimental Neurology.

[13]  Akoev Gn.  Catecholamines, acetylcholine and excitability of mechanoreceptors. , 1980 .

[14]  P. Nathan,et al.  Painful peripheral states and sympathetic blocks. , 1978, Journal of neurology, neurosurgery, and psychiatry.

[15]  H. E. Torebjörk,et al.  Afferent C units responding to mechanical, thermal and chemical stimuli in human non-glabrous skin. , 1974, Acta physiologica Scandinavica.

[16]  Patrick D. Wall,et al.  Ongoing activity in peripheral nerves: The physiology and pharmacology of impulses originating from a neuroma ☆ , 1974 .

[17]  Nixon Da.  The microbiological detection and determination of meso-inositol. , 1956 .

[18]  W. Loewenstein.  Modulation of cutaneous mechanoreceptors by sympathetic stimulation , 1956, The Journal of physiology.