Vestibular stimulation leads to distinct hemodynamic patterning

Kerman, Ilan A.; Yates, Bill J

doi:10.1152/ajpregu.2000.279.1.r118

Cited by 51 publications

(61 citation statements)

References 23 publications

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“…However, hindlimb muscle spindles also receive limited sympathetic nervous system innervation (11,14,16), and thus we cannot exclude the possibility that some central nervous system neurons were infected though these projections. Even so, considering the relatively large number of muscle vasoconstrictor fibers that are present within peripheral nerves (10,20,26,27,32), it seems reasonable to conclude that most of the circuitry that was labeled in these experiments participated in controlling muscle blood flow. Caution must also be used when interpreting the results of the experiment involving the injection of PRV recombinants into the left and right gastrocnemius, because the infection of a neuron by one virus can limit its susceptibility to be infected by a second virus (23).…”

Section: Discussionmentioning

confidence: 95%

“…It is possible that the lateral vestibular nucleus and red nucleus are mainly involved in adjusting sympathetic outflow to muscle, but not other tissues. Vestibular signals participate in regulating hindlimb blood flow (20,22,41), and thus the infected neurons in the lateral vestibular nucleus likely are components of the neural pathway that mediates this response. The red nucleus is not typically considered to participate in autonomic regulation but instead plays a fundamental role in motor control in the rat (13,24).…”

Section: Discussionmentioning

confidence: 99%

“…This conclusion is partly based on the observation that when sodium glutamate microinjections were used to activate neuronal cell bodies in the principal vasomotor region of the brain stem, the rostral ventrolateral medulla (RVLM) of anesthetized cats, no separation could be found between sites that caused vasoconstriction in forelimb and hindlimb muscles (26), despite the fact that injection sites that specifically altered blood flow to particular tissues were readily identifiable (27). However, other studies have indicated that particular sensory stimuli, such as those detected by the vestibular system, can evoke discrete changes in the activity of sympathetic efferents innervating blood vessels in different limb muscles and trigger anatomically patterned changes in blood flow (20,22,41). These latter observations suggest that distinct populations of brain stem neurons regulate the sympathetic outflow to each skeletal muscle.…”

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confidence: 99%

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Transneuronal tracing of neural pathways that regulate hindlimb muscle blood flow

Lee

Lois²,

Troupe³

et al. 2007

American Journal of Physiology-Regulatory, Integrative and Comp

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Lee T-K, Lois JH, Troupe JH, Wilson TD, Yates BJ. Transneuronal tracing of neural pathways that regulate hindlimb muscle blood flow. Am J Physiol Regul Integr Comp Physiol 292: R1532-R1541, 2007. First published December 7, 2007 doi:10.1152/ajpregu.00633.2006.-Despite considerable interest in the neural mechanisms that regulate muscle blood flow, the descending pathways that control sympathetic outflow to skeletal muscles are not adequately understood. The present study mapped these pathways through the transneuronal transport of two recombinant strains of pseudorabies virus (PRV) injected into the gastrocnemius muscles in the left and right hindlimbs of rats: PRV-152 and PRV-BaBlu. To prevent PRV from being transmitted to the brain stem via motor circuitry, a spinal transection was performed just below the L2 level. Infected neurons were observed bilaterally in all of the areas of the brain that have previously been shown to contribute to regulating sympathetic outflow: the medullary raphe nuclei, rostral ventrolateral medulla (RVLM), rostral ventromedial medulla, A5 adrenergic cell group region, locus coeruleus, nucleus subcoeruleus, and the paraventricular nucleus of the hypothalamus. The RVLM, the brain stem region typically considered to play the largest role in regulating muscle blood flow, contained neurons infected following the shortest postinoculation survival times. Approximately half of the infected RVLM neurons were immunopositive for tyrosine hydroxylase, indicating that they were catecholaminergic. Many (47%) of the RVLM neurons were dually infected by the recombinants of PRV injected into the left and right hindlimb, suggesting that the central nervous system has a limited capacity to independently regulate blood flow to left and right hindlimb muscles.

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Section: Discussionmentioning

confidence: 95%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

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Transneuronal tracing of neural pathways that regulate hindlimb muscle blood flow

Lee

Lois²,

Troupe³

et al. 2007

American Journal of Physiology-Regulatory, Integrative and Comp

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“…Experiments conducted on anesthetized (13,15) and conscious (32) cats demonstrated that the vestibular system influences on different vascular beds are not equivalent. Electrical stimulation of vestibular afferents produces opposite changes in the activity of sympathetic nerve fibers innervating arterioles in skeletal muscle of the upper and lower body (15) and reciprocal changes in forelimb and hindlimb blood flow (13).…”

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confidence: 99%

Effects of postural changes and removal of vestibular inputs on blood flow to and from the hindlimb of conscious felines

Yavorcik¹,

Reighard²,

Misra³

et al. 2009

American Journal of Physiology-Regulatory, Integrative and Comp

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September 30, 2009; doi:10.1152 doi:10. /ajpregu.00551.2009 show that the vestibular system contributes to blood pressure regulation. Prior studies reported that lesions that eliminate inputs from the inner ears attenuate the vasoconstriction that ordinarily occurs in the hindlimbs of conscious cats during head-up rotations. These data led to the hypothesis that labyrinthine-deficient animals would experience considerable lower body blood pooling during head-up postural alterations. The present study tested this hypothesis by comparing blood flow though the femoral artery and vein of conscious cats during 20 -60°head-up tilts from the prone position before and after removal of vestibular inputs. In vestibular-intact animals, venous return from the hindlimb dropped considerably at the onset of head-up tilts and, at 5 s after the initiation of 60°rotations, was 66% lower than when the animals were prone. However, after the animals were maintained in the head-up position for another 15 s, venous return was just 33% lower than before the tilt commenced. At the same time point, arterial inflow to the limb had decreased 32% from baseline, such that the decrease in blood flow out of the limb due to the force of gravity was precisely matched by a reduction in blood reaching the limb. After vestibular lesions, the decline in femoral artery blood flow that ordinarily occurs during head-up tilts was attenuated, such that more blood flowed into the leg. Contrary to expectations, in most animals, venous return was facilitated, such that no more blood accumulated in the hindlimb than when labyrinthine signals were present. These data show that peripheral blood pooling is unlikely to account for the fluctuations in blood pressure that can occur during postural changes of animals lacking inputs from the inner ear. Instead, alterations in total peripheral resistance following vestibular dysfunction could affect the regulation of blood pressure.blood flow patterning; venous return; cardiac output; orthostatic hypotension HEAD-UP BODY ROTATIONS in humans or animals typically result in some pooling of blood in the periphery and a resulting reduction in return of blood to the heart. Because cardiac output is directly related to cardiac preload (Starling's law of the heart) (27), cardiac output tends to decrease during head-up movements (25). Furthermore, cardiac output and peripheral vascular resistance determine systemic blood pressure, such that the sympathetic nervous system must produce a rapid net increase in peripheral resistance by inducing vasoconstriction at the onset of head-up body rotations to maintain stable blood pressure (7). Arterial baroreceptor mechanisms play an important role in regulating peripheral vasoconstriction during postural alterations (23). In addition, there is considerable evidence from studies in animals (6,8,10,11,21,22,32) and humans (1,4,12,23,26,28,30) that the vestibular system also participates in triggering increases in vasomotor activity during movements that promote peripheral blood pooling...

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“…This study observed that, on denervation of the vestibular nerve, tilted cats were unable to maintain arterial blood pressure (8). Later studies reported that stimulation of the otolith organs increases sympathetic outflow and vascular resistance in the cat (12,32,33).…”

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confidence: 83%