Chapter 21 Cardiovascular control by the rostral ventrolateral medulla in the conscious dog

Dormer, Kenneth J.; Bedford, T. G.

doi:10.1016/s0079-6123(08)62016-6

Cited by 16 publications

(14 citation statements)

References 32 publications

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“…Animal studies [1][2][3][4][5][6][7] have clearly defined the role of the sympathoexcitatory neurons of the RVLM and the inhibitory neurons of the caudal ventrolateral medulla in blood pressure regulation. The C1 group of adrenergic neurons in the RVLM has a major efferent pathway to the intermediolateral column of cells (preganglionic sympathetic neurons) in the spinal cord.…”

Section: Discussionmentioning

confidence: 99%

“…In animals, electrical or chemical stimulation of the RVLM results in vasoconstriction and hypertension, and bilateral inhibition or chemical destruction of the RVLM results in hypotension. [1][2][3] In baboons, experimental pulsatile compression of the left VLM induced a hypertensive blood pressure response. 4 Human postmortem studies have demonstrated that the C1 adrenergic neurons of the RVLM are within 1 mm from surface of the ROS.…”

Section: Discussionmentioning

confidence: 99%

“…Centrally mediated hyperactivity of the sympathetic nervous system has been proposed as an "initiator" of early EHTN and may provide a major contribution to sustaining elevated blood pressure over the long term in some patients. Studies in animal models [1][2][3][4][5][6][7] have confirmed the presence of sympathoexcitatory bulbospinal neurons in the rostral ventrolateral medulla (RVLM) and their important role in the control of blood pressure. In humans, those neurons are thought to be in the retro-olivary sulcus (ROS), just anterior to the root entry zone of the glossopharyngeal and vagus nerves.…”

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Vascular Compression of the Rostral Ventrolateral Medulla in Sympathetic Mediated Essential Hypertension

et al. 2000

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Abstract-The pathophysiological factors of neurogenic or sympathetically mediated essential hypertension are unknown.Neurons close to the surface of the ventrolateral medulla (specifically, in the retro-olivary sulcus [ROS]) are integrally involved in the control of blood pressure by means of efferent connections to presympathetic neurons in the spinal cord. It is hypothesized that vascular contact with the ROS is pathogenically involved in neurogenically mediated hypertension. We evaluated that theory in 20 subjects with uncomplicated stage 1 to stage 2 essential hypertension (EHTN) (18 of whom completed the study). The baseline supine plasma norepinephrine level served as an index of central sympathetic outflow. The response of blood pressure to clonidine was used as a surrogate marker for neurogenically mediated hypertension. We also examined the relationship between those markers and evidence of anatomic abnormalities in the area of the ROS that was provided by magnetic resonance imaging. A vessel contacted the left ROS in 5 of the 18 subjects. Those 5 subjects had higher plasma norepinephrine concentrations than did the 13 subjects without this vascular contact (358Ϯ46 versus 76Ϯ43 pg/mL, PϽ0.001). These 5 subjects also exhibited a significant depressor response to clonidine that tended to be greater than that seen in the 13 subjects without vascular contact (Ϫ20.6Ϯ3.2 versus Ϫ13.6Ϯ9 mm Hg). Both race and baseline mean blood pressure had only an independent effect on the depressor response to clonidine. The findings are consistent with the theory that vascular contact with the left ROS may contribute to neurogenically mediated "essential" hypertension in some patients. (Hypertension. 2000;36:78-82.)Key Words: hypertension, essential Ⅲ norepinephrine Ⅲ medulla oblongata Ⅲ clonidine Ⅲ sympathetic nervous system T he cause of essential hypertension (EHTN) remains unclear and is probably multifactorial. Centrally mediated hyperactivity of the sympathetic nervous system has been proposed as an "initiator" of early EHTN and may provide a major contribution to sustaining elevated blood pressure over the long term in some patients. Studies in animal models [1][2][3][4][5][6][7] have confirmed the presence of sympathoexcitatory bulbospinal neurons in the rostral ventrolateral medulla (RVLM) and their important role in the control of blood pressure. In humans, those neurons are thought to be in the retro-olivary sulcus (ROS), just anterior to the root entry zone of the glossopharyngeal and vagus nerves. 8 Several studies 9 -11 in which the results of magnetic resonance imaging (MRI) and autopsy were used have indicated an increased incidence of vascular compression of the left ventrolateral medulla (VLM) in patients with EHTN. However, the reported incidences have been inconsistent, as has been the laterality of vascular contact, and the exact location of vessel contact was not made clear. Moreover, microvascular decompression to relieve such vascular contact with the VLM has not been uniformly effective in normaliz...

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

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Vascular Compression of the Rostral Ventrolateral Medulla in Sympathetic Mediated Essential Hypertension

et al. 2000

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“…28 The CVLM was defined as the region of the ventral brain stem between the nucleus reticularis ventralis, the nucleus reticularis, and the nucleus ambiguus. The RVLM was defined as a region ventromedial to the facial nucleus, as described by Dormer et al 29 and corresponding to Figures 28 to 30 in Lim et al 27 The AP was defined as the tissue protruding into the fourth ventricle lateral to the dorsal motor nucleus of the vagus and the nucleus gracilis 28 27 Counts were taken unilaterally from each region. The numbers of Fos-Lipositive cells, as indicated by black nuclear staining, were counted by observers who were blind to the experimental conditions of the dogs.…”

Section: Microscopic Analysis and Quantificationmentioning

confidence: 99%

“…Thus, the results of this study should be carefully interpreted with this caveat in mind. Nonetheless, as the quantification of Fos-Li-positive cells was based on precise neuroanatomical landmarks, [27][28][29] we feel it is highly likely that the increased Fos-Li staining in the NTS, CVLM, and RVLM of obese dogs reflected activation of neurons in the baroreflex pathway. Additionally, the activation pattern of neurons in the NTS and CVLM, presumably reflecting baroreflex suppression of sympathoexcitatory RVLM neurons, was essentially the same as we reported previously in conscious dogs during elevations in arterial pressure produced by both acute and chronic ANG II infusion.…”

Section: Lohmeier Et Al Central Baroreflex Pathway In Obesity Hypertementioning

confidence: 99%

Sustained Activation of the Central Baroreceptor Pathway in Obesity Hypertension

2003

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Abstract-The major goal of this study was to determine whether there is increased activation of medullary neurons that participate in the central baroreceptor reflex pathway in dogs with obesity-induced hypertension, a model of hypertension that is associated with increased sympathetic activity. We used Fos-like (Fos-Li) protein immunohistochemical methods to determine activation of neurons in the nucleus tractus solitarius (NTS), caudal ventrolateral medulla (CVLM), and rostral ventrolateral medulla (RVLM). Dogs were fed either a regular diet or an identical diet with the addition of 0.5 to 0.9 kg of cooked beef fat. After Ϸ6 weeks of the high fat diet, body weight (36.3Ϯ0.4 vs 21.5Ϯ0.5 kg), mean arterial pressure (105Ϯ4 vs 91Ϯ3 mm Hg), and heart rate (97Ϯ4 vs 70Ϯ3 bpm) were significantly greater in obese than in control dogs, respectively. There was little Fos-Li immunoreactivity in medullary neurons of control dogs but marked reactivity in obese dogs. Specifically, the number of Fos-Li-positive cells in the NTS and CVLM was 3 to 5 times greater in obese than in control dogs. Furthermore, despite sustained activation of these baroreceptorsensitive neurons, there was a significantly greater number of Fos-Li positive cells in the RVLM of dogs fed the high fat diet. As baroreceptor suppression of sympathoexcitatory cells in the RVLM is mediated by activation of neurons in the NTS and CVLM, these results support recent findings indicating that baroreflex suppression of sympathetic activity is a long-term compensatory response in hypertension. However, sympathoexcitatory inputs onto RVLM neurons would appear to predominate over the inhibitory effects of the baroreflex in obesity hypertension. Key Words: angiotensin Ⅲ hypertension, obesity Ⅲ baroreflex Ⅲ central nervous system Ⅲ brain T here is considerable evidence that activation of the sympathetic nervous system plays an important role in the pathogenesis of hypertension. 1-3 However, the factors that chronically influence sympathetic activity and the precise mechanisms that mediate neurally induced hypertension are unclear. In large part, this has been due to technical limitations that prevent assessment of sympathetic function under chronic conditions. An area of long-standing interest, but one of considerable uncertainty, concerns the potential impact of baroreflexes on sympathetic activity and arterial pressure in hypertension. Clearly, baroreflex function is often impaired in chronic hypertension, 4 but whether baroreflex dysfunction contributes to increased sympathetic activity and the severity of hypertension is unresolved.The hypothesis that baroreflex dysfunction contributes to increased sympathetic activity in hypertension implies that baroreflexes normally play a role in the chronic (as well as the acute) regulation of body fluid volumes and arterial pressure. On one hand, a major argument against this possibility is that baroreflexes reset in the direction of the prevailing level of arterial pressure. 5 On the other hand, although chronic resetting is...

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Posterior fossa brain tumors and arterial hypertension

Kan¹,

Couldwell²

2006

Neurosurg Rev

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Hypertension caused by arterial compression of the rostral ventrolateral medulla is well described. Much less information is available on the association between neurogenic hypertension and posterior fossa brain tumors. To date, multiple reports have supported the impression that a small subpopulation of patients with posterior fossa tumors can present with arterial hypertension, and many of those patients achieved significant improvement of their hypertension after tumor resection and medullary decompression. To review the relationship between posterior fossa brain tumors and hypertension, we detail the history, basic science, and clinical reports along with an illustrative case regarding this topic.

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Chapter 21 Cardiovascular control by the rostral ventrolateral medulla in the conscious dog

Cited by 16 publications

References 32 publications

Vascular Compression of the Rostral Ventrolateral Medulla in Sympathetic Mediated Essential Hypertension

Vascular Compression of the Rostral Ventrolateral Medulla in Sympathetic Mediated Essential Hypertension

Sustained Activation of the Central Baroreceptor Pathway in Obesity Hypertension

Posterior fossa brain tumors and arterial hypertension

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