Blood flow increases in the skin of the anaesthetized rat that follow antidromic sensory nerve stimulation and strong mechanical stimulation

Lynn, Bruce; Cotsell, B.

doi:10.1016/0304-3940(92)90415-4

Cited by 19 publications

(15 citation statements)

References 15 publications

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“…As in the rabbit, the vasoactive nociceptive units in the rat had relatively low mechanical sensitivity. This therefore provides an explanation as to why the kinds of pressures that excite most rat cutaneous polymodal nociceptor units do not result in flare (Lynn & Cotsell, 1992). There was no difference between the vasodilator and non-vasodilator polymodal units in the rat in terms of their heat sensitivity.…”

Section: Species Differencesmentioning

confidence: 76%

The Relationship between Cutaneous C Fibre Type and Antidromic Vasodilatation in the Rabbit and the Rat

Gee

Lynn

Cotsell

1997

The Journal of Physiology

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Skin blood flow was monitored during antidromic stimulation of identified cutaneous C fibres in fine filaments dissected from the saphenous nerve of anaesthetized rabbits and rats. The techniques used to monitor skin blood flow were laser Doppler perfusion imaging and laser Doppler flowmetry. In the rabbit filaments a total of thirty‐three C fibres were tested for their ability to produce antidromic vasodilatation. The only C fibres found to have vasodilator actions were of the polymodal nociceptor afferent class, and fourteen (50%) of the twenty‐eight polymodal nociceptor units tested were vasoactive. The afferent receptive fields of polymodal nociceptor afferents were mapped carefully using suprathreshold mechanical stimuli, and there was a good correlation between afferent receptive field area and area of vasodilatation. In the rat, eleven of the fifty‐four C fibres antidromically stimulated had vasodilator actions. All eleven vasoactive C fibres were nociceptive and comprised seven polymodal nociceptor units, two heat nociceptor units and two incompletely classified nociceptor units. The area of increased blood flow was always coincident with the afferent field of the stimulated unit. In the rat the vasodilator units were not evenly distributed over the saphenous nerve receptive field. Nine of the eleven vasoactive C fibres had receptive fields located on the foot or the digits, and only two were on the ankle or lower leg. Overall, the population of nociceptive C fibres was evenly distributed over the saphenous nerve receptive field. In both the rabbit and the rat, a subclass of polymodal nociceptor afferents form the majority of the vasoactive units and will make the main contribution to axon reflex flare and other neurogenic inflammatory responses involving vasodilatation. The vasoactive polymodal nociceptor units tend to have relatively low mechanical sensitivity, although they have typical heat thresholds. In the rat heat nociceptor units also have vasodilator actions. However, such heat nociceptor units form a minor functional class of afferent C fibre in the rat saphenous nerve, and are not found in the rabbit saphenous nerve. The findings from this study in the rabbit and the rat are compared with the situation in pig skin. The close relationship between afferent receptive field area and spread of flare across species is noted, and the way these measures increase with body size is discussed.

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Section: Species Differencesmentioning

confidence: 76%

The Relationship between Cutaneous C Fibre Type and Antidromic Vasodilatation in the Rabbit and the Rat

Gee

Lynn

Cotsell

1997

The Journal of Physiology

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“…The release of neuropeptides from the terminal endings of the excited axon caused this flare reaction [11]. This increase of blood flow can be evoked by transcutaneous electrical stimulation [1], and maximum vasodilatation has been recorded at low frequencies of around 1 Hz [12]. Increasing the pulse frequencies of the electrical stimuli at a suprathreshold intensity further enhanced neuropeptide release in vitro [13] and flare area in humans in vivo [14].…”

Section: Axonal Responsementioning

confidence: 99%

Rapid flare development evoked by current frequency-dependent stimulation analyzed by full-field laser perfusion imaging

et al. 2007

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We analyzed, with a new imaging technique, the rapid axon reflex flare responses in human skin upon transcutaneous delivery of electrical stimuli at 1, 5, 10 and 50 Hz in single bursts of five pulses each. Two-dimensional perfusion images covering an area of 8 x 8 cm(2) were captured at 25 Hz and their averages saved at 0.5 Hz. The stimulation caused an axon reflex flare (maximum 3 cm(2), 20 s after stimulation) that gradually resolved within 2 min. Maximum flare responses developed at 5 Hz, whereas pain ratings increased with stimulation frequency. The highest neuropeptide release at 5 Hz correlates to the discharge characteristics of mechanoinsensitive C-fibers, whereas the maximum pain intensity at 50 Hz may be attributed to the activation of A-delta fibers.

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“…see Szolcsanyi, 1984). However, little attention has been paid to the fact that polymodal nociceptors respond to relatively low pressures that themselves do not produce flare (Lynn & Cotsell, 1992 (Lynn, Faulstroh & Pierau, 1995a), is specialized to produce vasodilatation in the skin.…”

mentioning

confidence: 99%

The vasodilator component of neurogenic inflammation is caused by a special subclass of heat‐sensitive nociceptors in the skin of the pig.

Lynn¹,

Schütterle²,

Pierau³

1996

The Journal of Physiology

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1. Skin blood flow has been imaged during stimulation of fine nerve filaments containing small numbers of identified C fibre units. Filaments were dissected from the saphenous nerve of anaesthetized pigs. 2. Stimulation of filaments containing C heat nociceptor units gave small areas of elevated blood flow (average increase 96 %, n = 11) restricted to the afferent receptive field. The extent of the areas of raised blood flow was imaged completely for 8 units. The average extent of vasodilatation in the direction of greatest spread was 8 mm and the maximum spread in any unit was 13 mm. 3. Stimulation of C polymodal nociceptor units never caused increases in blood flow7 in or near their receptive fields. 4. Localized noxious stimuli (55°C or intradermal injection of capsaicin) caused flare extending 7-15 mm in the same skin region. 5. In agreement with the axon reflex model, spread of flare was restricted to the zone innervated by the terminals of single C fibre units. 6. It is concluded that the C heat nociceptor units are the major class of afferent involved in the flare reaction in the skin of the pig. C polymodal nociceptor units do not appear to be involved in flare in this species. The probable situation in human skin, which is also innervated by heat nociceptors, is discussed.

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Blood flow increases in the skin of the anaesthetized rat that follow antidromic sensory nerve stimulation and strong mechanical stimulation

Cited by 19 publications

References 15 publications

The Relationship between Cutaneous C Fibre Type and Antidromic Vasodilatation in the Rabbit and the Rat

The Relationship between Cutaneous C Fibre Type and Antidromic Vasodilatation in the Rabbit and the Rat

Rapid flare development evoked by current frequency-dependent stimulation analyzed by full-field laser perfusion imaging

The vasodilator component of neurogenic inflammation is caused by a special subclass of heat‐sensitive nociceptors in the skin of the pig.

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