Glutamatergic and GABAergic inputs to the RVL mediate cardiovascular adjustments to noxious stimulation
Data
2001-02-01
Autores
Possas, Olga Sueli 
Lopes, Oswaldo Ubriaco
Cravo, Sergio Luiz
Tipo
Artigo
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Resumo
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.
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Citação
American Journal Of Physiology-regulatory Integrative And Comparative Physiology. Bethesda: Amer Physiological Soc, v. 280, n. 2, p. R434-R440, 2001.