Nitric oxide modulation of glutamatergic, baroreflex, and cardiopulmonary transmission in the nucleus of the solitary tract

Nitric oxide modulation of glutamatergic, baroreflex, and cardiopulmonary transmission in the nucleus of the solitary tract

Author Dias, ACR Google Scholar
Vitela, M. Google Scholar
Colombari, Eduardo Autor UNIFESP Google Scholar
Mifflin, S. W. Google Scholar
Institution Univ Texas
Universidade Federal de São Paulo (UNIFESP)
Abstract The neuromodulatory effect of NO on glutamatergic transmission has been studied in several brain areas. Our previous single-cell studies suggested that NO facilitates glutamatergic transmission in the nucleus of the solitary tract (NTS). in this study, we examined the effect of the nitric oxide synthase (NOS) inhibitor NG-nitro-L-arginine methyl ester (L-NAME) on glutamatergic and reflex transmission in the NTS. We measured mean arterial pressure (MAP), heart rate (HR), and renal sympathetic nerve activity (RSNA) from Inactin-anesthetized Sprague-Dawley rats. Bilateral microinjections of L-NAME (10 nmol/100 nl) into the NTS did not cause significant changes in basal MAP, HR, or RSNA. Unilateral microinjection of (RS)-alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA, 1 pmol/100 nl) into the NTS decreased MAP and RSNA. Fifteen minutes after L-NAME microinjections, AMPA-evoked cardiovascular changes were significantly reduced. N-methyl-D-aspartate (NMDA, 0.5 pmol/100 nl) microinjection into the NTS decreased MAP, HR, and RSNA. NMDA-evoked falls in MAP, HR, and RSNA were significantly reduced 30 min after L-NAME. To examine baroreceptor and cardiopulmonary reflex function, L-NAME was microinjected at multiple sites within the rostro-caudal extent of the NTS. Baroreflex function was tested with phenylephrine (PE, 25 mug iv) before and after L-NAME. Five minutes after L-NAME the decrease in RSNA caused by PE was significantly reduced. To examine cardiopulmonary reflex function, phenylbiguanide (PBG, 8 mug/kg) was injected into the right atrium. PBG-evoked hypotension, bradycardia, and RSNA reduction were significantly attenuated 5 min after L-NAME. Our results indicate that inhibition of NOS within the NTS attenuates baro- and cardiopulmonary reflexes, suggesting that NO plays a physiologically significant neuromodulatory role in cardiovascular regulation.
Keywords (RS)-alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid
N-methyl-D aspartate
baroreceptor and cardiopulmonary reflexes
cardiovascular regulation
renal sympathetic nerve activity
Language English
Date 2005-01-01
Published in American Journal of Physiology-heart and Circulatory Physiology. Bethesda: Amer Physiological Soc, v. 288, n. 1, p. H256-H262, 2005.
ISSN 0363-6135 (Sherpa/Romeo, impact factor)
Publisher Amer Physiological Soc
Extent H256-H262
Access rights Open access Open Access
Type Article
Web of Science ID WOS:000225733000037

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