Central nitric oxide modulates hindquarter vasodilation elicited by AMPA receptor stimulation in the NTS of conscious rats

Central nitric oxide modulates hindquarter vasodilation elicited by AMPA receptor stimulation in the NTS of conscious rats

Author Dias, Ana Carolina Rodrigues Google Scholar
Colombari, Eduardo Autor UNIFESP Google Scholar
Institution Universidade Federal de São Paulo (UNIFESP)
Univ Estadual São Paulo
Abstract Microinjection of S-alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid ( AMPA) in the nucleus of the solitary tract (NTS) of conscious rats causes hypertension, bradycardia, and vasoconstriction in the renal, mesenteric, and hindquarter vascular beds. in the hindquarter, the initial vasoconstriction is followed by vasodilation with AMPA doses > 5 pmol/100 nl. To test the hypothesis that this vasodilation is caused by activation of a nitroxidergic pathway in the NTS, we examined the effect of pretreatment with the nitric oxide synthase inhibitor N-G-nitro-L- arginine methyl ester (L-NAME, 10 nmol/ 100 nl, microinjected into the NTS) on changes in mean arterial pressure, heart rate, and regional vascular conductance (VC) induced by microinjection of AMPA ( 10 pmol/100 nl in the NTS) in conscious rats. AMPA increased hindquarter VC by 18 +/- 4%, but after pretreatment with L-NAME, AMPA reduced hindquarter VC by 16 +/- 7% and 17 +/- 9% ( 5 and 15 min after pretreatment, P < 0.05 compared with before pretreatment). Pretreatment with L-NAME reduced AMPA-induced bradycardia from 122 +/- 40 to 92 +/- 32 beats/min but did not alter the hypertension induced by AMPA ( 35 +/- 5 mmHg before pretreatment, 43 +/- 6 mmHg after pretreatment). Control injections with D-NAME did not affect resting values or the response to AMPA. the present study shows that stimulation of AMPA receptors in the NTS activates both vasodilatatory and vasoconstrictor mechanisms and that the vasodilatatory mechanism depends on production of nitric oxide in the NTS.
Keywords nitric oxide synthase
regional vascular conductance
cardiovascular regulation
Language English
Date 2006-05-01
Published in American Journal of Physiology-regulatory Integrative and Comparative Physiology. Bethesda: Amer Physiological Soc, v. 290, n. 5, p. R1330-R1336, 2006.
ISSN 0363-6119 (Sherpa/Romeo, impact factor)
Publisher Amer Physiological Soc
Extent R1330-R1336
Origin http://dx.doi.org/10.1152/ajpregu.00150.2005
Access rights Open access Open Access
Type Article
Web of Science ID WOS:000236664400021
URI http://repositorio.unifesp.br/handle/11600/28863

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