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Tipo do documento: Artigo
Título: Discharge of RVLM vasomotor neurons is not increased in anesthetized angiotensin II-salt hypertensive rats
Autor: Pedrino, Gustavo Rodrigues
Calderon, Alfredo S.
Andrade, Mary Ann
Cravo, Sergio Luiz Domingues
Toney, Glenn M.
Abstract: Neurons of the rostral ventrolateral medulla (RVLM) are critical for generating and regulating sympathetic nerve activity (SNA). Systemic administration of ANG II combined with a high-salt diet induces hypertension that is postulated to involve elevated SNA. However, a functional role for RVLM vasomotor neurons in ANG II-salt hypertension has not been established. Here we tested the hypothesis that RVLM vasomotor neurons have exaggerated resting discharge in rats with ANG II-salt hypertension. Rats in the hypertensive (HT) group consumed a high-salt (2% NaCl) diet and received an infusion of ANG II (150 ng·kg 1·min 1 sc) for 14 days. Rats in the normotensive (NT) group consumed a normal salt (0.4% NaCl) diet and were infused with normal saline. Telemetric recordings in conscious rats revealed that mean arterial pressure (MAP) was significantly increased in HT compared with NT rats (P 0.001). Under anesthesia (urethane/chloralose), MAP remained elevated in HT compared with NT rats (P 0.01). Extracellular single unit recordings in HT (n 28) and NT (n 22) rats revealed that barosensitive RVLM neurons in both groups (HT, 23 cells; NT, 34 cells) had similar cardiac rhythmicity and resting discharge. However, a greater (P 0.01) increase of MAP was needed to silence discharge of neurons in HT (17 cells, 44 5 mmHg) than in NT (28 cells, 29 3 mmHg) rats. Maximum firing rates during arterial baroreceptor unloading were similar across groups. We conclude that heightened resting discharge of sympathoexcitatory RVLM neurons is not required for maintenance of neurogenic ANG II-salt hypertension.
Palavras-chave: Angiotensin II
Sympathetic nerve activity
High-salt diet
Single unit recording
Rostral ventrolateral medulla vasomotor neurons
País: Estados unidos
Unidade acadêmica: Instituto de Ciências Biológicas - ICB (RG)
Citação: PEDRINO, Gustavo R. et al. Discharge of RVLM vasomotor neurons is not increased in anesthetized angiotensin II-salt hypertensive rats. American Journal of Physiology. Heart and Circulatory Physiology, Rockville, v. 305, n. 12, p. H1781-H1789, 2013.
Tipo de acesso: Acesso Aberto
Identificador do documento: 10.1152/ajpheart.00657.2013
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Identificador do documento: 10.1152/ajpheart.00657.2013
Data de publicação: 2013
Aparece nas coleções:ICB - Artigos publicados em periódicos

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