Modifications of the vestibular nerve activity by stimulation of the efferent vestibular system

1963 ◽  
Vol 19 (1) ◽  
pp. 39-39 ◽  
Author(s):  
O. Sala
Keyword(s):  
Vestibular System ◽  
Vestibular Nerve ◽  
Nerve Activity ◽  
Stimulation Of ◽  
Efferent Vestibular System

scholarly journals Role of the heart in blood pressure lowering during chronic baroreflex activation: insight from an in silico analysis

2018 ◽  
Vol 315 (5) ◽  
pp. H1368-H1382 ◽  
Author(s):  
John S. Clemmer ◽  
W. Andrew Pruett ◽  
Robert L. Hester ◽  
Radu Iliescu ◽  
Thomas E. Lohmeier
Keyword(s):  
Blood Pressure ◽  
Mathematical Model ◽  
Renal Denervation ◽  
Sympathetic Nerve Activity ◽  
Blood Pressure Lowering ◽  
Nerve Activity ◽  
Renal Sympathetic Nerve Activity ◽  
Pressure Lowering ◽  
Renal Sympathetic ◽  
Stimulation Of

Electrical stimulation of the baroreflex chronically suppresses sympathetic activity and arterial pressure and is currently being evaluated for the treatment of resistant hypertension. The antihypertensive effects of baroreflex activation are often attributed to renal sympathoinhibition. However, baroreflex activation also decreases heart rate, and robust blood pressure lowering occurs even after renal denervation. Because controlling renal sympathetic nerve activity (RSNA) and cardiac autonomic activity cannot be achieved experimentally, we used an established mathematical model of human physiology (HumMod) to provide mechanistic insights into their relative and combined contributions to the cardiovascular responses during baroreflex activation. Three-week responses to baroreflex activation closely mimicked experimental observations in dogs including decreases in blood pressure, heart rate, and plasma norepinephrine and increases in plasma atrial natriuretic peptide (ANP), providing validation of the model. Simulations showed that baroreflex-induced alterations in cardiac sympathetic and parasympathetic activity lead to a sustained depression of cardiac function and increased secretion of ANP. Increased ANP and suppression of RSNA both enhanced renal excretory function and accounted for most of the chronic blood pressure lowering during baroreflex activation. However, when suppression of RSNA was blocked, the blood pressure response to baroreflex activation was not appreciably impaired due to inordinate fluid accumulation and further increases in atrial pressure and ANP secretion. These simulations provide a mechanistic understanding of experimental and clinical observations showing that baroreflex activation effectively lowers blood pressure in subjects with previous renal denervation. NEW & NOTEWORTHY Both experimental and clinical studies have shown that the presence of renal nerves is not an obligate requirement for sustained reductions in blood pressure during chronic electrical stimulation of the carotid baroreflex. Simulations using HumMod, a mathematical model of integrative human physiology, indicated that both increased secretion of atrial natriuretic peptide and suppressed renal sympathetic nerve activity play key roles in mediating long-term reductions in blood pressure during chronic baroreflex activation.

Electronmicroscopic and electrophysiological studies of the teat branch of the XIII thoracic nerve: relationship with lactation in the rat

1988 ◽  
Vol 118 (3) ◽  
pp. 471-483 ◽  
Author(s):  
L. M. Voloschin ◽  
E. Décima ◽  
J. H. Tramezzani
Keyword(s):  
Electrical Stimulation ◽  
Conduction Velocity ◽  
Action Potentials ◽  
Silent Period ◽  
High Amplitude ◽  
Milk Ejection ◽  
Nerve Activity ◽  
Thoracic Nerve ◽  
Myelinated Fibres ◽  
Stimulation Of

ABSTRACT Electrical stimulation of the XIII thoracic nerve (the 'mammary nerve') causes milk ejection and the release of prolactin and other hormones. We have analysed the route of the suckling stimulus at the level of different subgroups of fibres of the teat branch of the XIII thoracic nerve (TBTN), which innervates the nipple and surrounding skin, and assessed the micromorphology of the TBTN in relation to lactation. There were 844 ± 63 and 868 ± 141 (s.e.m.) nerve fibres in the TBTN (85% non-myelinated) in virgin and lactating rats respectively. Non-myelinated fibres were enlarged in lactating rats; the modal value being 0·3–0·4 μm2 for virgin and 0·4–0·5 μm2 for lactating rats (P > 0·001; Kolmogorov–Smirnov test). The modal value for myelinated fibres was 3–6 μm2 in both groups. The compound action potential of the TBTN in response to electrical stimulation showed two early volleys produced by the Aα- and Aδ-subgroups of myelinated fibres (conduction velocity rate of 60 and 14 m/s respectively), and a late third volley originated in non-myelinated fibres ('C') group; conduction velocity rate 1·4 m/s). Before milk ejection the suckling pups caused 'double bursts' of fibre activity in the Aδ fibres of the TBTN. Each 'double burst' consisted of low amplitude action potentials and comprised two multiple discharges (33–37 ms each) separated by a silent period of around 35 ms. The 'double bursts' occurred at a frequency of 3–4/s, were triggered by the stimulation of the nipple and were related to fast cheek movements visible only by watching the pups closely. In contrast, the Aα fibres of the TBTN showed brief bursts of high amplitude potentials before milk ejection. These were triggered by the stimulation of cutaneous receptors during gross slow sucking motions of the pup (jaw movements). Immediately before the triggering of milk ejection the mother was always asleep and a low nerve activity was recorded in the TBTN at this time. When reflex milk ejection occurred, the mother woke and a brisk increase in nerve activity was detected; this decreased when milk ejection was accomplished. In conscious rats the double-burst type of discharges in Aδ fibres was not observed, possibly because this activity cannot be detected by the recording methods currently employed in conscious animals. During milk ejection, action potentials of high amplitude were conveyed in the Aα fibres of the TBTN. During the treading time of the stretch reaction (SR), a brisk increase in activity occurred in larger fibres; during the stretching periods of the SR a burst-type discharge was again observed in slow-conducting afferents; when the pups changed nipple an abrupt increase in activity occurred in larger fibres. In summary, the non-myelinated fibres of the TBTN are increased in diameter during lactation, and the pattern of suckling-evoked nerve activity in myelinated fibres showed that (a) the double burst of Aδ fibres, produced by individual sucks before milk ejection, could be one of the conditions required for the triggering of the reflex, and (b) the nerve activity displayed during milk-ejection action may result, at least in part, from 'non-specific' stimulation of cutaneous receptors. J. Endocr. (1988) 118, 471–483

Neural, hemodynamic, and renal responses to stimulation of intestinal receptors

1987 ◽  
Vol 253 (5) ◽  
pp. H1167-H1176 ◽  
Author(s):  
L. C. Weaver ◽  
S. Genovesi ◽  
A. Stella ◽  
A. Zanchetti
Keyword(s):  
Sympathetic Nerve ◽  
Reflex Response ◽  
Renal Nerves ◽  
Nerve Activity ◽  
Renal Vasoconstriction ◽  
Pressor Responses ◽  
Fractional Excretion Of Sodium ◽  
Intestinal Receptors ◽  
Renal Responses ◽  
Stimulation Of

Stimulation of visceral receptors with bradykinin has been shown to cause reflex increases in sympathetic nerve activity and systemic arterial pressure. In this investigation, serosal receptors of the intestine were stimulated by bradykinin in anesthetized cats to 1) compare mesenteric and renal sympathetic responses, 2) compare hemodynamic responses in mesenteric and renal beds, and 3) determine changes in renal function. This stimulation in intact animals caused pressor responses, significantly greater excitation of mesenteric than renal nerves, significantly greater mesenteric than renal vasoconstriction, diuresis, natriuresis, and, in denervated kidneys, increases in fractional sodium excretion. In vagotomized, sinoaortic-denervated cats, stimulation of intestinal receptors caused excitation of mesenteric nerve activity greater than renal for only 30 s. This sympathetic reflex response led to pressor responses, equal mesenteric and renal vasoconstriction, diuresis, natriuresis, and increased fractional excretion of sodium only in denervated kidneys. When abdominal perfusion pressure was held constant with an aortic snare in these same animals, the sympathetic reflexes initially caused greater mesenteric than renal vasoconstriction and antidiuresis and antinatriuresis only in innervated kidneys. These findings demonstrate that the intensity of hemodynamic and renal responses to stimulation of visceral receptors correlates well with the magnitude of sympathetic nerve responses.

Gestational effects on volume-sensitive cardiopulmonary receptor reflexes in the rat

1995 ◽  
Vol 268 (3) ◽  
pp. R736-R743 ◽  
Author(s):  
T. Hines ◽  
S. W. Mifflin
Keyword(s):  
Sympathetic Nerve Activity ◽  
Right Atrial ◽  
Nerve Activity ◽  
Pregnant Rats ◽  
Renal Sympathetic Nerve Activity ◽  
Cell Discharge ◽  
Afferent Stimulus ◽  
Gallamine Triethiodide ◽  
Renal Sympathetic ◽  
Stimulation Of

We tested the hypothesis that augmented reflex sympathoinhibition mediated by volume-sensitive cardiopulmonary (CP) receptors contributes to the vasodilation of pregnancy by comparing responses to acute volume expansion in 21-day-pregnant and age-matched virgin rats (n = 7) that were anesthetized (pentobarbital sodium, 50 mg/kg ip), paralyzed (gallamine triethiodide, 25 mg/kg iv), ventilated, and had undergone bilateral sinoaortic denervation. CP receptors were stimulated with intra-atrial injections of saline (50, 100, 200, and 300 microliter), and the following variables were recorded: 1) mean right atrial pressure (MRAP) to index the afferent stimulus intensity; 2) cell discharge in the nucleus tractus solitarii (NTS), the primary central terminus for CP afferents; and 3) mean arterial pressure (MAP), heart rate (HR), and renal sympathetic nerve activity (RSNA) to assess efferent reflex effects. Basal MAP was significantly lower in pregnant (71.5 +/- 3.8 mmHg) than in virgin rats (86.6 +/- 3.1 mmHg), and plasma volume was expanded in the pregnant group (17.6 +/- 1.1 vs. 10.0 +/- 0.7 ml, P < 0.05). Baseline MRAP was similar between groups. Saline injections evoked graded increases in MRAP, which were larger in gravid animals (P < 0.05). Volume injections evoked similar changes in NTS cell discharge between groups, but the responses were nongraded. Despite larger changes in MRAP in gravid rats, reflex effects on RSNA and HR were similar to those in control animals, and effects on MAP were attenuated in the pregnant group. We conclude that larger changes in MRAP in pregnant rats during stimulation of CP receptors are not associated with larger changes in central or efferent components of this reflex.(ABSTRACT TRUNCATED AT 250 WORDS)

Development of the rat efferent vestibular system on the ground and in microgravity

2001 ◽  
Vol 128 (1) ◽  
pp. 35-44 ◽  
Author(s):  
Danielle Demêmes ◽  
Claude J Dechesne ◽  
Stéphanie Venteo ◽  
Florence Gaven ◽  
Jacqueline Raymond
Keyword(s):  
Vestibular System ◽  
Efferent Vestibular System

Suppression of the vestibular short-latency evoked potential by electrical stimulation of the central vestibular system

2018 ◽  
Vol 361 ◽  
pp. 23-35 ◽  
Author(s):  
Christopher J. Pastras ◽  
Ian S. Curthoys ◽  
Ljiljana Sokolic ◽  
Daniel J. Brown
Keyword(s):  
Electrical Stimulation ◽  
Vestibular System ◽  
Evoked Potential ◽  
Short Latency ◽  
Stimulation Of
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