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Rostral ventrolateral medulla: an integrative site for muscle vasodilation during defense-alerting reactions.
Cell Mol Neurobiol. 2003 Oct; 23(4-5):579-95.CM

Abstract

1. Evidence gathered over the last 30 years has firmly established that the rostral ventrolateral medulla (RVLM) is a major vasomotor center in the brainstem, harboring sympathetic premotor neurons responsible for generating and maintaining basal vasomotor tone and resting levels of arterial blood pressure. Although the RVLM has been almost exclusively classified as a vasopressor area, in this report we review some evidence suggesting a prominent role of the RVLM in muscle vasodilation during defense-alerting responses. 2. Defense-alerting reactions are a broad class of behavior including flexion of a limb, fight/flight responses, apologies, etc. They comprise species-distinctive motor and neurovegetative adjustments. Cardiovascular responses include hypertension, tachycardia, visceral vasoconstriction, and muscle vasodilation. Since defense-alerting reactions generally involve intense motor activation, muscle vasodilation is regarded as a key feature of these responses 3. In anesthetized or unanesthetized-decerebrate animals, natural or electrical stimulation of cutaneous and muscle afferents produced hypertension, tachycardia, and vasodilation restricted to the stimulated limb. 4. Unilateral inactivation of the RVLM contralateral to the stimulated limb abolished cardiovascular adjustments to stimulation of cutaneous and muscle afferents. Within the RVLM glutamatergic synapses mediate pressor responses, whereas GABAergic synapses mediates muscle vasodilation. 5. In urethane-anesthetized rats, electrical stimulation of the hypothalamus elicited hypertension, tachycardia, visceral vasoconstriction, and hindlimb vasodilation. The hindlimb vasodilation induced by hypothalamic stimulation is a complex response, involving reduction of sympathetic vasoconstrictor tone, release of catecholamines by the adrenal medulla, and a still unknown system that may use nitric oxide as a mediator. 6. Blockade of glutamatergic transmission within the RVLM selectively blocks muscle vasodilation induced by hypothalamic stimulation. 7. The results obtained suggest that, besides its role in the generation and maintenance of the sympathetic vasoconstrictor drive, the RVLM is also critical for vasodilatory responses during defense reactions. The RVLM may contain several, distinctive mechanisms for muscle vasodilation. Anatomical and functional characterization of these pathways may represent a breakthrough in our understanding of cardiovascular control in normal and/or pathological conditions.

Authors+Show Affiliations

Department of Physiology, Universidade Federal de São Paulo, 04023-060 São Paulo, SP, Brazil. sldcravo@fcr.epm.brNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't
Review

Language

eng

PubMed ID

14514017

Citation

Cravo, Sergio L., et al. "Rostral Ventrolateral Medulla: an Integrative Site for Muscle Vasodilation During Defense-alerting Reactions." Cellular and Molecular Neurobiology, vol. 23, no. 4-5, 2003, pp. 579-95.
Cravo SL, Possas OS, Ferreira-Neto ML. Rostral ventrolateral medulla: an integrative site for muscle vasodilation during defense-alerting reactions. Cell Mol Neurobiol. 2003;23(4-5):579-95.
Cravo, S. L., Possas, O. S., & Ferreira-Neto, M. L. (2003). Rostral ventrolateral medulla: an integrative site for muscle vasodilation during defense-alerting reactions. Cellular and Molecular Neurobiology, 23(4-5), 579-95.
Cravo SL, Possas OS, Ferreira-Neto ML. Rostral Ventrolateral Medulla: an Integrative Site for Muscle Vasodilation During Defense-alerting Reactions. Cell Mol Neurobiol. 2003;23(4-5):579-95. PubMed PMID: 14514017.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Rostral ventrolateral medulla: an integrative site for muscle vasodilation during defense-alerting reactions. AU - Cravo,Sergio L, AU - Possas,Olga S, AU - Ferreira-Neto,Marcos L, PY - 2003/9/30/pubmed PY - 2004/5/1/medline PY - 2003/9/30/entrez SP - 579 EP - 95 JF - Cellular and molecular neurobiology JO - Cell. Mol. Neurobiol. VL - 23 IS - 4-5 N2 - 1. Evidence gathered over the last 30 years has firmly established that the rostral ventrolateral medulla (RVLM) is a major vasomotor center in the brainstem, harboring sympathetic premotor neurons responsible for generating and maintaining basal vasomotor tone and resting levels of arterial blood pressure. Although the RVLM has been almost exclusively classified as a vasopressor area, in this report we review some evidence suggesting a prominent role of the RVLM in muscle vasodilation during defense-alerting responses. 2. Defense-alerting reactions are a broad class of behavior including flexion of a limb, fight/flight responses, apologies, etc. They comprise species-distinctive motor and neurovegetative adjustments. Cardiovascular responses include hypertension, tachycardia, visceral vasoconstriction, and muscle vasodilation. Since defense-alerting reactions generally involve intense motor activation, muscle vasodilation is regarded as a key feature of these responses 3. In anesthetized or unanesthetized-decerebrate animals, natural or electrical stimulation of cutaneous and muscle afferents produced hypertension, tachycardia, and vasodilation restricted to the stimulated limb. 4. Unilateral inactivation of the RVLM contralateral to the stimulated limb abolished cardiovascular adjustments to stimulation of cutaneous and muscle afferents. Within the RVLM glutamatergic synapses mediate pressor responses, whereas GABAergic synapses mediates muscle vasodilation. 5. In urethane-anesthetized rats, electrical stimulation of the hypothalamus elicited hypertension, tachycardia, visceral vasoconstriction, and hindlimb vasodilation. The hindlimb vasodilation induced by hypothalamic stimulation is a complex response, involving reduction of sympathetic vasoconstrictor tone, release of catecholamines by the adrenal medulla, and a still unknown system that may use nitric oxide as a mediator. 6. Blockade of glutamatergic transmission within the RVLM selectively blocks muscle vasodilation induced by hypothalamic stimulation. 7. The results obtained suggest that, besides its role in the generation and maintenance of the sympathetic vasoconstrictor drive, the RVLM is also critical for vasodilatory responses during defense reactions. The RVLM may contain several, distinctive mechanisms for muscle vasodilation. Anatomical and functional characterization of these pathways may represent a breakthrough in our understanding of cardiovascular control in normal and/or pathological conditions. SN - 0272-4340 UR - https://www.unboundmedicine.com/medline/citation/14514017/Rostral_ventrolateral_medulla:_an_integrative_site_for_muscle_vasodilation_during_defense_alerting_reactions_ L2 - http://ovidsp.ovid.com/ovidweb.cgi?T=JS&PAGE=linkout&SEARCH=14514017.ui DB - PRIME DP - Unbound Medicine ER -