HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 286/3/R451    most recent 00569.2003v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (5) Citing Articles via Google Scholar Google Scholar Articles by Orer, H. S. Articles by Barman, S. M. Search for Related Content PubMed PubMed Citation Articles by Orer, H. S. Articles by Barman, S. M.

NEUROHUMORAL CONTROL OF CIRCULATION AND HYPERTENSION

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

¹Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan 48824; and ²Department of Pharmacology, Faculty of Medicine, Hacettepe University, 06100 Ankara, Turkey

Submitted 1 October 2003 ; accepted in final form 4 November 2003

We tested the hypothesis that blockade of N-methyl-D-aspartate (NMDA) and non-NMDA receptors on medullary lateral tegmental field (LTF) neurons would reduce the sympathoexcitatory responses elicited by electrical stimulation of vagal, trigeminal, and sciatic afferents, posterior hypothalamus, and midbrain periaqueductal gray as well as by activation of arterial chemoreceptors with intravenous NaCN. Bilateral microinjection of a non-NMDA receptor antagonist into LTF of urethane-anesthetized cats significantly decreased vagal afferent-evoked excitatory responses in inferior cardiac and vertebral nerves to 29 ± 8 and 24 ± 6% of control (n = 7), respectively. Likewise, blockade of non-NMDA receptors significantly reduced chemoreceptor reflex-induced increases in inferior cardiac (from 210 ± 22 to 129 ± 13% of control; n = 4) and vertebral nerves (from 253 ± 41 to 154 ± 20% of control; n = 7) and mean arterial pressure (from 39 ± 7 to 21 ± 5 mmHg; n = 8). Microinjection of muscimol, but not an NMDA receptor antagonist, caused similar attenuation of these excitatory responses. Sympathoexcitatory responses to the other stimuli were not attenuated by microinjection of a non-NMDA receptor antagonist or muscimol into LTF. In fact, excitatory responses elicited by stimulation of trigeminal, and in some cases sciatic, afferents were enhanced. These data reveal two new roles for the LTF in control of sympathetic nerve activity in cats. One, LTF neurons are involved in mediating sympathoexcitation elicited by activation of vagal afferents and arterial chemoreceptors, primarily via activation of non-NMDA receptors. Two, non-NMDA receptor-mediated activation of other LTF neurons tonically suppresses transmission in trigeminal-sympathetic and sciatic-sympathetic reflex pathways.

arterial chemoreceptor reflex; excitatory amino acid receptors; sciatic-sympathetic reflex; trigeminal-sympathetic reflex; vagal-sympathetic reflex

This article has been cited by other articles:

				H. S. Orer, G. L. Gebber, and S. M. Barman Medullary lateral tegmental field neurons influence the timing and pattern of phrenic nerve activity in cats J Appl Physiol, August 1, 2006; 101(2): 521 - 530. [Abstract] [Full Text] [PDF]

				S. M. Barman, S. W. Phillips, and G. L. Gebber Medullary lateral tegmental field mediates the cardiovascular but not respiratory component of the Bezold-Jarisch reflex in the cat Am J Physiol Regulatory Integrative Comp Physiol, December 1, 2005; 289(6): R1693 - R1702. [Abstract] [Full Text] [PDF]

				S. W. Phillips, G. L. Gebber, and S. M. Barman Medullary lateral tegmental field: control of respiratory rate and vagal lung inflation afferent influences on sympathetic nerve discharge Am J Physiol Regulatory Integrative Comp Physiol, May 1, 2005; 288(5): R1396 - R1410. [Abstract] [Full Text] [PDF]

				R. Dampney Medullary pathways regulating sympathetic outflow: the need for more lateral thinking Am J Physiol Regulatory Integrative Comp Physiol, March 1, 2004; 286(3): R446 - R448. [Full Text] [PDF]