Role of the Sympathetic Innervation of the Pacinian Corpuscle

SUMMARY1. Sympathetic effects on the activity of single guard hair receptors and slowly adapting, type II mechanoreceptors were studied in anaesthetized cats.2. Spontaneous activity in type II receptors and mechanically evoked activity in both type II and guard hair receptors was recorded both without and with electrical stimulation of the lumbar sympathetic trunk.3. Almost all guard hair receptors were desensitized by sympathetic stimulation, the mean effect being an increase in threshold to 2-2 times the unconditioned value.4. One third of the more slowly adapting guard hair units showed sympathetically induced spontaneous activity.5. These sympathetic effects on guard hair receptors appear not to be related to pilomotor responses or to changes in central arterial pressure.6. Individual type HI receptors were found to be excited by skin stretch along one of two axes: either parallel or perpendicular to the long axis of the leg. Intermediate orientations were not observed.7. 'Perpendicular' units showed marked increases in resting discharge but no change in mechanical sensitivity during sympathetic stimulation. 'Parallel' units were unaffected.8. The sympathetic effect appeared not to be related to changes in blood pressure or skin tension.9. It is suggested that the location and orientation of stretch sensitivity of these receptors make them well suited for detection of limb movements; however, no satisfactory functional explanation was found for the pronounced sympathetic facilitation of only one subset of the receptors.

Section: Discussionmentioning

confidence: 98%

Section: Discussionmentioning

confidence: 99%

Sympathetically induced changes in the responses of guard hair and type II receptors in the cat.

Pierce¹,

Roberts²

1981

“…Chernetski, 1964). The mechanosensitivity of pacinian corpuscles in cat mesentery and mesocolon is modulated by sympathetic post-ganglionic fibres which stimulate pacinian fiadrenoceptors (Loewenstein & Altamirano-Orrego, 1956;Schiff, 1974). Stimulation of sympathetic nerves inhibits ganglionic transmission in cat stomach and small intestine (Kewenter, 1965;Jansson & Martinson, 1966) and in the guinea-pig inhibits acetylcholine output in response to pelvic nerve stimulation (Beani et al 1969).…”

Section: Discussionmentioning

confidence: 99%

A study of peripheral input to and its control by post‐ganglionic neurones of the inferior mesenteric ganglion.

Szurszewski¹,

Weems²

1976

101

SUMMARY1. Intracellular recordings were made, in vitro, from neurones of guinea-pig inferior mesenteric ganglia (IMG) attached, via the lumbar colonic nerves, to segments of distal colon.2. 'Spontaneous' synaptic input from colonic afferent fibres was observed in 79% of the neurones tested. In any given preparation, the level and pattern of this synaptic input to different neurones varied considerably. 3. Superfusion of colonic segments with drugs (papaverine, isoprenaline, and adenosine triphosphate) which reduce colonic motility decreased colonic afferent input to IMG neurones. 4. Superfusion of colonic segments with acetylcholine or stimulation of pelvic nerves, both of which increase colonic motility, increased colonic afferent input to 1MG neurones.5. Superfusion of colonic segments with either atropine or tubocurarine reduced the level of 'spontaneous', colonic afferent input. However, distension of these relaxed segments increased the colonic afferent input.6. Repetitive stimulation of preganglionic inputs to the IMG inhibited afferent input from drug relaxed segments of colon that were moderately distended by the injection of air into the lumen. Superfusion of the colon with phentolamine blocked this inhibition.7. The results of this study suggest that IMG neurones receive afferent input from mechanoreceptors located in the distal colon and that the mechanosensitivity of this afferent pathway is in part controlled by efferent noradrenergic neurones of the IMG. The IMG-colon neural circuitry can therefore be considered to form a feed-back control system which participates in the regulation of colonic motility.

“…The exact nature of this influence is unclear since different authors describe excitatory, suppressive or mixed responses depending on the species used and on the protocol. In general all the experiments using amphibian or in vitro mammalian preparations have reported purely excitatory responses to sympathetic stimulation or superfused noradrenaline (Loewenstein, 1956;Loewenstein & Altamirano-Orrego, 1956;Chernetski, 1964;Spray, 1974; Schiff, 1974;Calof, Jones & Roberts, 1981). In contrast, those using in vivo mammalian preparations have reported either mixed responses (Hunt, 1960;Eldred, Schnitzlein & Buchwald, 1960;Edwall & Scott, 197 1 ;Freeman & Rowe, 1981;Pierce & Roberts, 1981;Roberts & Levitt, 1982;Barasi & Lynn, 1983), or suppressive responses (Nilsson, 1972;Cash & Linden, 1982;Barasi & Lynn, 1983;Passatori & Filippi, 1983).…”

Section: Introductionmentioning

confidence: 99%

Sympathetic modulation of cold‐receptive neurones in the trigeminal system of the rat.

Davies¹

1985

SUMMARY1. The effects of cervical sympathetic electrical stimulation on the activity of cold-receptive neurones in the trigeminal system of the rat have been studied.2. Sympathetic stimulation caused excitation and/or suppression of cold-receptive cells in the trigeminal nucleus caudalis. The responses were complex but within any one cell low-frequency stimulation (below 5 Hz) usually (81 % of cells) caused excitation, while high-frequency stimulation (above 10 Hz) caused excitation and suppression.3. The temperature of the cutaneous receptive fields was 'clamped' with a thermode. Measurements of surface and intradermal temperatures suggested that the temperature fall caused by sympathetic stimulation was not sufficient to account for the increased firing rate observed.4. The suppression was blocked by a low dose of phentolamine; it was mimicked by carotid occlusion and may be a consequence of vasoconstriction.5. The excitation was resistant to ,8-blockade; it was best mimicked by the z-agonist phenylephrine.6. Similar frequency-dependent excitations and suppressions, and responses to pharmacological agonists, were obtained in recordings from cold-receptive primary afferent neurones in the trigeminal ganglion.7. The excitation may be a complex secondary effect, or there may be a direct c-receptor-mediated excitation of cold-receptive primary afferent fibres by the sympathetic system.