Role of the medullary lateral tegmental field in reflex-mediated sympathoexcitation in cats

Orer, Hakan S.; Gebber, Gerard L.; Phillips, Shaun W.; Barman, Susan M.

doi:10.1152/ajpregu.00569.2003

Cited by 17 publications

(42 citation statements)

References 47 publications

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“…The inferior cardiac and vertebral branches of the left stellate ganglia were exposed retropleurally by removing the head of the 1st rib (31,46). These nerves project to the heart and vasculature of the forelimb, respectively.…”

Section: Sympathetic and Phrenic Nerve Recordingsmentioning

confidence: 99%

“…Several laboratories have shown that this region of the cat brain stem contains neurons with activity correlated to SND (7-9, 12, 18, 30, 56), and chemical activation of the LTF can alter blood pressure (17,26,32,41,54). Importantly, there is a growing body of evidence supporting the view that, at least in the cat, the LTF plays a crucial role not only in setting the basal level of SND (9, 10, 45) but also in mediating responses to activation of baroreceptor and chemoreceptor afferents (45,46). Specifically, blockade of non-N-methyl-D-aspartate (non-NMDA) receptors in the LTF reduced the level of basal SND and the sympathoexcitatory effect of arterial chemoreceptor activation (10,45,46), whereas blockade of NMDA receptors attenuated baroreflexmediated sympathoinhibition (45).…”

mentioning

confidence: 99%

“…Importantly, there is a growing body of evidence supporting the view that, at least in the cat, the LTF plays a crucial role not only in setting the basal level of SND (9, 10, 45) but also in mediating responses to activation of baroreceptor and chemoreceptor afferents (45,46). Specifically, blockade of non-N-methyl-D-aspartate (non-NMDA) receptors in the LTF reduced the level of basal SND and the sympathoexcitatory effect of arterial chemoreceptor activation (10,45,46), whereas blockade of NMDA receptors attenuated baroreflexmediated sympathoinhibition (45). These observations prompted us in the current study to test the hypothesis that the LTF is involved in mediating the effects of vagal lung inflation afferents on SND and PNA.…”

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confidence: 99%

“…However, the neuronal connections beyond this point that are responsible for changes in SND have not been identified. A recent study from this laboratory (46) showed that the sympathoexcitatory and sympathoinhibitory effects of electrical stimulation of cervical vagal afferents were prevented by microinjection of the GABA agonist muscimol into the medullary lateral tegmental field (LTF) in cats. The LTF includes portions of nucleus reticularis parvocellularis and nucleus reticularis ventralis.…”

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Medullary lateral tegmental field: control of respiratory rate and vagal lung inflation afferent influences on sympathetic nerve discharge

Phillips¹,

Gebber²,

Barman³

2005

American Journal of Physiology-Regulatory, Integrative and Comp

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Phillips, Shaun W., Gerard L. Gebber, and Susan M. Barman. Medullary lateral tegmental field: control of respiratory rate and vagal lung inflation afferent influences on sympathetic nerve discharge. Am J Physiol Regul Integr Comp Physiol 288: R1396 -R1410, 2005. First published December 16, 2004; doi:10.1152/ajpregu.00632.2004.-We used spectral analysis and event-triggered averaging to determine the effects of chemical inactivation of the medullary lateral tegmental field (LTF) on 1) the relationship of intratracheal pressure (ITP, an index of vagal lung inflation afferent activity) to sympathetic nerve discharge (SND) and phrenic nerve activity (PNA) and 2) central respiratory rate in paralyzed, artificially ventilated dial-urethane-anesthetized cats. ITP-SND coherence value at the frequency of artificial ventilation was significantly (P Ͻ 0.05; n ϭ 18) reduced from 0.73 Ϯ 0.04 (mean Ϯ SE) to 0.24 Ϯ 0.04 after bilateral microinjection of muscimol into the LTF. Central respiratory rate was unexpectedly increased in 12 of these experiments (0.28 Ϯ 0.03 vs. 0.95 Ϯ 0.25 Hz). The ITP-PNA coherence value was variably affected by chemical inactivation of the LTF. It was unchanged when central respiratory rate was also not altered, decreased when respiratory rate was increased above the rate of artificial ventilation, and increased when respiratory rate was raised from a value below the rate of artificial ventilation to the same frequency as the ventilator. Chemical inactivation of the LTF increased central respiratory rate in four of six vagotomized cats but did not significantly affect the PNA-SND coherence value. These data demonstrate that the LTF 1) plays a critical role in mediating the effects of vagal lung inflation afferents on SND but not PNA, 2) helps maintain central respiratory rate in the physiological range, but 3) is not involved in the coupling of central respiratory and sympathetic circuits. cardiorespiratory synchronization; dorsal respiratory group; HeringBreuer reflex; phrenic nerve activity; respiratory-related rhythm; ventral respiratory group IT HAS LONG BEEN RECOGNIZED that neural mechanisms controlling the respiratory and cardiovascular systems are tightly linked (25,34,38,49,55). This interaction facilitates the complementary functions of the two systems: respiration maintains appropriate levels of arterial blood gases, while the cardiovascular system transports these gases to and from tissues. One indication of this cardiorespiratory coordination was noted by Adrian et al. (1) in 1932 when they made the first recordings of sympathetic nerve discharge (SND). They found that the amplitude of the cardiac-related bursts of SND waxed and waned on the time scale of the respiratory cycle. There are at least two sources of respiratory modulation of SND: input from vagal lung inflation afferents and an influence of the respiratory rhythm generator on central sympathetic neurons (4 -6, 21, 25, 33-35, 59). Although some investigators (38, 49) have proposed that there is a common network controlling bo...

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Section: Sympathetic and Phrenic Nerve Recordingsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Medullary lateral tegmental field: control of respiratory rate and vagal lung inflation afferent influences on sympathetic nerve discharge

Phillips¹,

Gebber²,

Barman³

2005

American Journal of Physiology-Regulatory, Integrative and Comp

Self Cite

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“…Furthermore, blockade of N -methyl-D-aspartate (NMDA) receptors in the LTF abolished baroreceptor reflex control of sympathetic activity (Barman and Gebber 1987). In a recent study in cats, the same group showed that a blockade of non-NMDA receptors in the LTF significantly attenuated the reflex increase in cardiac and vertebral sympathetic nerve activity in response to electrical stimulation of vagal afferents or by activation of arterial chemo receptors (Orer et al 2004). On the other hand, the reflex sympathetic activation, in response to electrical stimulation of the sciatic or trigeminal nerve, was not affected by previous glutamatergic blockade within the LTF.…”

Section: The Rostral Ventrolateral Medulla and The Generation Of The mentioning

confidence: 96%

Role of the medulla oblongata in normal and high arterial blood pressure regulation: the contribution of Escola Paulista de Medicina - UNIFESP

Cravo

Campos

Colombari

et al. 2009

An. Acad. Bras. Ciênc.

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Several forms of experimental evidence gathered in the last 37 years have unequivocally established that the medulla oblongata harbors the main neural circuits responsible for generating the vasomotor tone and regulating arterial blood pressure. Our current understanding of this circuitry derives mainly from the studies of Pedro Guertzenstein, a former student who became Professor of Physiology at UNIFESP later, and his colleagues. In this review, we have summarized the main findings as well as our collaboration to a further understanding of the ventrolateral medulla and the control of arterial blood pressure under normal and pathological conditions.

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Processing of vestibular inputs by the medullary lateral tegmental field of conscious cats: implications for generation of motion sickness

et al. 2012

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The dorsolateral reticular formation of the caudal medulla, the lateral tegmental field (LTF), participates in generating vomiting. LTF neurons exhibited complex responses to vestibular stimulation in decerebrate cats, indicating that they received converging inputs from a variety of labyrinthine receptors. Such a convergence pattern of vestibular inputs is appropriate for a brain region that participates in generating motion sickness. Since responses of brainstem neurons to vestibular stimulation can differ between decerebrate and conscious animals, the current study examined the effects of whole-body rotations in vertical planes on the activity of LTF neurons in conscious felines. Wobble stimuli, fixed-amplitude tilts, the direction of which moves around the animal at a constant speed, were used to determine the response vector orientation, and also to ascertain whether neurons had spatial–temporal convergence (STC) behavior (which is due to the convergence of vestibular inputs with different spatial and temporal properties). The proportion of LTF neurons with STC behavior in conscious animals (25 %) was similar to that in decerebrate cats. Far fewer neurons in other regions of the feline brainstem had STC behavior, confirming findings that many LTF neurons receive converging inputs from a variety of labyrinthine receptors. However, responses to vertical plane vestibular stimulation were considerably different in decerebrate and conscious felines for LTF neurons lacking STC behavior. In decerebrate cats, most LTF neurons had graviceptive responses to rotations, similar to those of otolith organ afferents. However, in conscious animals, the response properties were similar to those of semicircular canal afferents. These differences show that higher centers of the brain that are removed during decerebration regulate the labyrinthine inputs relayed to the LTF, either by gating connections in the brainstem or by conveying vestibular inputs directly to the region.

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Role of the medullary lateral tegmental field in reflex-mediated sympathoexcitation in cats

Cited by 17 publications

References 47 publications

Medullary lateral tegmental field: control of respiratory rate and vagal lung inflation afferent influences on sympathetic nerve discharge

Medullary lateral tegmental field: control of respiratory rate and vagal lung inflation afferent influences on sympathetic nerve discharge

Role of the medulla oblongata in normal and high arterial blood pressure regulation: the contribution of Escola Paulista de Medicina - UNIFESP

Processing of vestibular inputs by the medullary lateral tegmental field of conscious cats: implications for generation of motion sickness

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