Cardiovascular responses to hydrogen peroxide into the nucleus tractus solitarius

Cardiovascular responses to hydrogen peroxide into the nucleus tractus solitarius

Author Cardoso, Leonardo Maximo Autor UNIFESP Google Scholar
Almeida Colombari, Debora Simoes de Google Scholar
Menani, Jose V. Google Scholar
Toney, Glenn M. Google Scholar
Chianca, Deoclecio Alves Google Scholar
Colombari, Eduardo Autor UNIFESP Google Scholar
Institution Universidade Federal de São Paulo (UNIFESP)
São Paulo State Univ
Univ Texas Hlth Sci Ctr San Antonio
Univ Fed Ouro Preto
Abstract Cardoso LM, Colombari DSA, Menani JV, Toney GM, Chianca Jr. DA, Colombari E. Cardiovascular responses to hydrogen peroxide into the nucleus tractus solitarius. Am J Physiol Regul Integr Comp Physiol 297: R462-R469, 2009. First published June 10, 2009; doi:10.1152/ajpregu.90796.2008.-The nucleus tractus solitarius (NTS), a major hindbrain area involved in cardiovascular regulation, receives primary afferent fibers from peripheral baroreceptors and chemoreceptors. Hydrogen peroxide (H(2)O(2)) is a relatively stable and diffusible reactive oxygen species (ROS), which acting centrally, may affect neural mechanisms. in the present study, we investigated effects of H(2)O(2) alone or combined with the glutamatergic antagonist kynurenate into the NTS on mean arterial pressure (MAP) and heart rate (HR). Conscious or anesthetized (urethane and alpha-chloralose) male Holtzman rats (280-320 g) were used. Injections of H(2)O(2) (125 to 1500 pmol/40 nl) into the intermediate NTS of anesthetized rats evoked dose-dependent and transient hypotension (-18 +/- 3 to -55 +/- 11 mmHg) and bradycardia (-16 +/- 5 to -116 +/- 40 bpm). Injection of the catalase inhibitor 3-amino-1,2,4-triazole (100 nmol/40 nl) into the NTS also produced hypotension and bradycardia. Previous injection of the ionotropic L-glutamate receptor antagonist kynurenate (7 nmol/40 nl) attenuated by 48% the bradycardic response, without changing the hypotension evoked by H(2)O(2) (500 pmol/40 nl) in anesthetized rats. the antioxidant L-ascorbate (600 pmol/80 nl) injected into the NTS attenuated the bradycardic (42%) and hypotensive (67%) responses to H(2)O(2) (500 pmol/40 nl) into the NTS. in conscious rats, injection of H(2)O(2) (50 nmol/100 nl) into the NTS also evoked intense bradycardia (-207 +/- 8 bpm) and hypotension (-54 +/- 6 mmHg) that were abolished by prior injection of kynurenate (7 nmol/100 nl). the results show that H(2)O(2) into the NTS induces hypotension and bradycardia probably due to activation of glutamatergic mechanisms.
Keywords reactive oxygen species
catalase inhibition
kynurenic acid
blood pressure
heart rate
Language English
Sponsor Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
National Institutes of Health
Grant number National Institutes of Health: HL-071645
Date 2009-08-01
Published in American Journal of Physiology-regulatory Integrative and Comparative Physiology. Bethesda: Amer Physiological Soc, v. 297, n. 2, p. R462-R469, 2009.
ISSN 0363-6119 (Sherpa/Romeo, impact factor)
Publisher Amer Physiological Soc
Extent R462-R469
Access rights Open access Open Access
Type Article
Web of Science ID WOS:000268187100026

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