Medullary lateral tegmental field mediates the cardiovascular but not respiratory component of the Bezold-Jarisch reflex in the cat

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

doi:10.1152/ajpregu.00406.2005

Cited by 10 publications

(17 citation statements)

References 39 publications

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“…One might also argue that the use of a mixture of diallylbarbiturate and urethane in our experiments interfered with the role of the NTS in mediating sympatho-sympathetic reflexes. However, several studies (3,4,11,22,29,35) show that this anesthetic regimen does not hinder the ability of NTS to mediate other reflexes (e.g., baroreceptor, Bezold-Jarisch, and lung-inflation).…”

Section: Discussionmentioning

confidence: 99%

“…Data from past work from this laboratory (11,31,32,35) raised two questions about the involvement of the LTF in reflex control of SND. Is the LTF an element of all autonomic reflex pathways in which the primary afferent terminates in the NTS?…”

Section: Perspectives and Significancementioning

confidence: 99%

“…On the basis of the data from the current study, the answer to the first question is a "qualified" "Yes"; the answer to the second question is a definitive "No." The LTF is involved in mediating sympathoexcitatory and sympathoinhibitory responses elicited by natural or electrical activation of afferent fibers in at least two visceral cranial nerves (vagus and glossopharyngeal), which synapse in the NTS (11,31,32,35), but not a somatic cranial nerve (trigeminal), which does not synapse in the NTS (32). The LTF does not mediate reflexes elicited by activation of somatic (sciatic) or visceral (SN, CN) afferent fibers that synapse in the dorsal horn of the spinal cord (32, current study).…”

Section: Perspectives and Significancementioning

confidence: 99%

“…Rather, our data show that LTF neurons are also elements of these reflex pathways. Specifically, microinjection of NMDA receptor antagonists into LTF significantly reduced baroreceptor and Bezold-Jarisch reflex-induced inhibition of SND (11,31). Modulation of SND by lung inflation afferents was also prevented by blockade of NMDA receptors in the LTF (S. M. Barman and G. L. Gebber, unpublished observation) or by chemical inactivation (muscimol microinjection) of this region (35).…”

mentioning

confidence: 92%

“…These data show that activation of non-NMDA receptors in the RVLM is a critical step in mediating the sympathosympathetic reflex. cardiac sympathetic afferents; caudal ventrolateral medulla; nucleus tractus solitarius; splanchnic afferents; sympathetic nerve discharge WORK FROM THIS LABORATORY (5,7,10,11,31,32,35) in the past decade or so has provided evidence that medullary lateral tegmental field (LTF) neurons play a crucial role in setting the resting pattern of sympathetic nerve discharge (SND) and in mediating at least some reflex-induced changes in SND in cats. These studies challenge two popular views of central control of cardiovascular function.…”

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confidence: 99%

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Rostral ventrolateral medullary but not medullary lateral tegmental field neurons mediate sympatho-sympathetic reflexes in cats

Barman

Orer

2010

American Journal of Physiology-Regulatory, Integrative and Comp

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This study was designed to build on past work from this laboratory by testing the hypothesis that medullary lateral tegmental field (LTF) neurons play a critical role in mediating sympathoexcitatory responses to activation of sympathetic afferent fibers. We studied the effects of microinjection of N-methyl-d-aspartate (NMDA) or non-NMDA receptor antagonists or muscimol bilaterally into the LTF on the area under the curve of the computer-averaged sympathoexcitatory potential in the right inferior cardiac nerve elicited by short trains of stimuli applied to afferent fibers in the left inferior cardiac or left splanchnic nerve (CN, SN) of baroreceptor-denervated and vagotomized cats anesthetized with a mixture of diallylbarbiturate and urethane. In contrast to our hypothesis, sympathoexcitatory responses to stimulation of CN (n = 5-7) or SN (n = 4-7) afferent fibers were not significantly affected by these procedures. We then determined whether the rostral and caudal ventrolateral medulla (RVLM, CVLM) and nucleus tractus solitarius (NTS) were involved in mediating these reflexes. Blockade of non-NMDA, but not NMDA, receptors in the RVLM significantly reduced the area under the curve of the sympathoexcitatory responses to electrical stimulation of either CN (P = 0.0110; n = 6) or SN (P = 0.0131; n = 5) afferent fibers. Neither blockade of excitatory amino acid receptors nor chemical inactivation of CVLM or NTS significantly affected the responses. These data show that activation of non-NMDA receptors in the RVLM is a critical step in mediating the sympatho-sympathetic reflex.

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Section: Discussionmentioning

confidence: 99%

Section: Perspectives and Significancementioning

confidence: 99%

Section: Perspectives and Significancementioning

confidence: 99%

mentioning

confidence: 92%

mentioning

confidence: 99%

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Rostral ventrolateral medullary but not medullary lateral tegmental field neurons mediate sympatho-sympathetic reflexes in cats

Barman

Orer

2010

American Journal of Physiology-Regulatory, Integrative and Comp

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New insights into the electrophysiology of brainstem circuits controlling blood pressure

Mifflin¹

2007

Current Science Inc

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The brainstem contains the necessary circuitry for the maintenance and regulation of arterial blood pressure. It has become increasingly clear in the past few years that the characteristics of the neurons that constitute these circuits are not static, but can be altered in the face of chronic changes in physiological state. Alterations in voltage-gated and ligand-gated ion channels have been reported in neurons located within the nucleus of the solitary tract and the nucleus ambiguus in response to hypertension and exposures to hypoxia and environmental pollutants (eg, ozone and cigarette smoke). A discussion of these neuronal adaptations, the mechanisms that might initiate and sustain the adaptations, and their potential significance is the focus of this brief review.

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Nonuniformity in the von Bezold-Jarisch reflex

Salo¹,

Woods²,

Anderson³

et al. 2007

American Journal of Physiology-Regulatory, Integrative and Comp

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The von Bezold-Jarisch reflex (BJR) is a vagally mediated chemoreflex from the heart and lungs, causing hypopnea, bradycardia, and inhibition of sympathetic vasomotor tone. However, cardiac sympathetic nerve activity (CSNA) has not been systematically compared with vasomotor activity during the BJR. In 11 urethane-anesthetized (1-1.5 g/kg iv), artificially ventilated rats, we measured CSNA simultaneously with lumbar sympathetic activity (LSNA) while the BJR was evoked by right atrial bolus injections of phenylbiguanide (0.5, 1.0, 1.5, and 2 microg). Nerve and heartbeat responses were analyzed by calculating normalized cumulative sums. LSNA and heartbeats were always reduced by the BJR. An excitatory "rebound" component often followed the inhibition of LSNA but never outweighed it. For CSNA, however, excitation usually (in 7 of 11 rats) outweighed any initial inhibition, such that the net response to phenylbiguanide was excitatory. The differences in net response between LSNA, CSNA, and heartbeats were all significant (P < 0.01). A second experimental series on seven rats showed that methyl atropine (1 mg/kg iv) abolished the bradycardia of the BJR, whereas subsequent bilateral vagotomy substantially reduced LSNA and CSNA responses, both excitatory and inhibitory. These findings show that, during the BJR, 1) CSNA is often excited, 2) there may be coactivation of sympathetic and parasympathetic drives to the heart, 3) divergent responses may be evoked simultaneously in cardiac vagal, cardiac sympathetic, and vasomotor nervous pathways, and 4) those divergent responses are mediated primarily by the vagi.

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Medullary lateral tegmental field mediates the cardiovascular but not respiratory component of the Bezold-Jarisch reflex in the cat

Cited by 10 publications

References 39 publications

Rostral ventrolateral medullary but not medullary lateral tegmental field neurons mediate sympatho-sympathetic reflexes in cats

Rostral ventrolateral medullary but not medullary lateral tegmental field neurons mediate sympatho-sympathetic reflexes in cats

New insights into the electrophysiology of brainstem circuits controlling blood pressure

Nonuniformity in the von Bezold-Jarisch reflex

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