Glutamatergic and GABAergic inputs to the RVL mediate cardiovascular adjustments to noxious stimulation

Glutamatergic and GABAergic inputs to the RVL mediate cardiovascular adjustments to noxious stimulation

Author Possas, Olga Sueli Autor UNIFESP Google Scholar
Lopes, Oswaldo Ubriaco Autor UNIFESP Google Scholar
Cravo, Sergio Luiz Autor UNIFESP Google Scholar
Institution Universidade Federal de São Paulo (UNIFESP)
Abstract Stimulation of cutaneous and muscle afferents induces several cardiovascular adjustments such as hypertension, tachycardia, and muscle vasodilation. Although previous studies have demonstrated that the rostral ventrolateral medulla (RVL) mediates sympathoexcitation and pressor responses to sciatic nerve stimulation (SNS), whether it also mediates blood flow adjustments remains unclear. Therefore, in the present study, we examined the role of the RVL in the vasodilation induced by SNS and the possible neurotransmitters involved. In Urethane-anesthetized, paralyzed, and artificially ventilated rats, SNS (square pulses, 1 ms, 20 Hz, 800-1200 muA, 10 s) produced increases in blood pressure, heart rate, blood flow, and vascular conductance of the stimulated limb. Unilateral microinjection of kainic acid (2 nmol/100 nl) into the RVL contralateral to the stimulated limb abolished cardiovascular adjustments to SNS. Unilateral microinjections of kynurenic acid (2 nmol/100 nl) selectively abolished the pressor response to SNS, whereas bicuculline (400 pmol/100 nl) abolished the increases in blood flow without changing the pressor response. These results suggest that glutamatergic synapses within the RVL mediate pressor responses, whereas GABAergic synapses may mediate the vasodilation to SNS.
Keywords blood flow
somatosympathetic reflexes
blood pressure
sciatic nerve
rostral ventrolateral medulla
Language English
Date 2001-02-01
Published in American Journal Of Physiology-regulatory Integrative And Comparative Physiology. Bethesda: Amer Physiological Soc, v. 280, n. 2, p. R434-R440, 2001.
ISSN 0363-6119 (Sherpa/Romeo, impact factor)
Publisher Amer Physiological Soc
Extent R434-R440
Origin http://ajpregu.physiology.org/content/280/2/R434
Access rights Open access Open Access
Type Article
Web of Science ID WOS:000166421300017
URI http://repositorio.unifesp.br/11600/42354

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