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Am J Physiol Regul Integr Comp Physiol 280: R434-R440, 2001;
0363-6119/01 $5.00
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Vol. 280, Issue 2, R434-R440, February 2001

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

Olga S. Possas, Oswaldo U. Lopes, and Sérgio L. Cravo

Department of Physiology, Federal University of São Paulo, Rua Botucatu, 862 São Paulo, SP 04023-060, Brazil

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 µA, 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.

blood flow; somatosympathetic reflexes; blood pressure; sciatic nerve; rostral ventrolateral medulla


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Am. J. Physiol. Regul. Integr. Comp. Physiol.Home page
D. N. Mayorov and G. A. Head
Glutamate receptors in RVLM modulate sympathetic baroreflex in conscious rabbits
Am J Physiol Regulatory Integrative Comp Physiol, February 1, 2003; 284(2): R511 - R519.
[Abstract] [Full Text] [PDF]




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