• JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
  • JoomlaWorks Simple Image Rotator
 
  Bookmark and Share
 
 
Master's Dissertation
DOI
https://doi.org/10.11606/D.17.2018.tde-17042018-161320
Document
Author
Full name
Jéssica Maria Sanches Lopes
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
Ribeirão Preto, 2017
Supervisor
Committee
Santos, Jose Eduardo Tanus dos (President)
Júnior, Wilson Salgado
Kemp, Rafael
Silva, Cristina Antoniali
Title in Portuguese
Efeitos de drogas inibidoras da secreção ácida do estômago sobre as respostas hipotensoras do nitrito de sódio
Keywords in Portuguese
Nitrito; Nitrosotióis; Omeprazol; Ranitidina
Abstract in Portuguese
O nitrito pode ser reduzido a NO de forma dependente do pH ácido do estômago ou por enzimas com atividade nitrito-redutase. O tratamento com omeprazol, previne parte dos efeitos anti-hipertensivos do nitrito administrado por via oral por aumentar o pH gástrico. Contudo, nenhum estudo até o momento avaliou se, assim como o omeprazol, a ranitidina também é capaz de atenuar os efeitos anti-hipertensivos do nitrito de sódio por aumentar o pH gástrico. Nesse estudo, examinamos se a administração oral de ranitidina poderia prejudicar os efeitos anti-hipertensivos do nitrito de sódio administrados por via oral, por interferir na formação de NO e espécies nitrosiladas a partir do nitrito. A fim de verificar a influência da ranitidina no efeito hipotensor do nitrito de sódio, utilizamos animais tratados agudamente com LNAME pré-tratados com ranitidina, omeprazol e veículo e, posteriormente, com nitrito de sódio 15mg/kg. Como esperado, o tratamento com L-NAME resultou em aumento na pressão arterial média (PAM). O pH gástrico foi diferente entre os grupos, tendo um aumento no pH dos animais tratados com ranitidina e omeprazol, quando comparado ao veículo, e os tampões tinham o mesmo pH do veículo e das drogas. O nitrito de sódio exerceu efeitos anti-hipertensivos significativos nos grupos estudados. No entanto, foram observadas menores diminuições na PAM em ratos tratados com omeprazol e ranitidina em comparação aos ratos que receberam veículo. Esses achados foram associados a diminuições nas concentrações gástricas de NO e diminuições nos níveis plasmáticos de espécies nitrosiladas. Além disso, houve aumento nas concentrações de nitrito no estômago. Não foram observadas diferenças nas concentrações de nitrito no plasma. Além disso, não foram observadas diferenças nos níveis de NOx no plasma e estômago entre os grupos do estudo. Os animais tratados com tampão apresentaram resultados similares aos tratados com as drogas. Nossos resultados sugerem que a ranitidina, ao aumentar o pH gástrico, afeta as respostas anti-hipertensivas ao nitrito de sódio oral por diminuir a formação de NO e espécies nitrosiladas. Este fato é reforçado pelo aumento do nitrito no estômago, sugerindo uma diminuição na conversão de nitrito a NO e espécies nitrosiladas no ambiente gástrico.
Title in English
Effects of inhibitors of acid secretion of stomach on the hypotensive responses to sodium nitrite
Keywords in English
Nitrite; Nitrosylated species; Omeprazole; Ranitidine
Abstract in English
Nitrite can be reduced to NO depending on acidic pH of the stomach or by enzymes with nitrite reductase activity. Treatment with omeprazole attenuates the antihypertensive effects of oral nitrite by increasing of gastric pH. However, studies are still necessary to further evaluate wheter ranitidine is also able to attenuate the antihypertensive effects of sodium nitrite by increasing gastric pH. In this study, we examined whether oral administration of ranitidine could impair oral antihypertensive effects of sodium nitrite by interfering with the formation of NO and nitrosylated species from nitrite. In order to analyze the influence of ranitidine under hypotensive effect of sodium nitrite, rats were treated with L-NAME and pretreated with ranitidine, omeprazole, vehicle or buffer, subsequently all the groups were treated with sodium nitrite 15 mg/kg. The L-NAME treatment increase mean arterial pressure (MAP). The gastric pH was different among the groups, there was an increased in rats gastric pH treated with ranitidine and omeprazole compared to the vehicle. The buffer group had the same pH of vehicle and drugs treatment. Sodium nitrite exerted significant antihypertensive effects in the groups studied. However, lesser decreases in MAP were observed in rats treated with omeprazole and ranitidine compared to rats that received vehicle. These findings were associated with a lower NO gastric concentrations as well as nitrosylated species plasma levels. In addition, there was an increased in nitrite concentrations in the stomach. No differences were observed in plasma nitrite levels. Moreover, there was not any significant difference in plasma and stomach NOx levels among the studied groups. The rats treated with buffer showed similar results to those treated with the drugs. Together these data demonstrated that ranitidine, through increased gastric pH, affects antihypertensive responses to oral sodium nitrite by reducing the formation of NO and nitrosylated species. This fact is reinforced by higher levels in nitrite concentrations in the stomach, thereby it suggests a lower conversion of nitrite to NO and nitrosylated species in the gastric environment.
 
WARNING - Viewing this document is conditioned on your acceptance of the following terms of use:
This document is only for private use for research and teaching activities. Reproduction for commercial use is forbidden. This rights cover the whole data about this document as well as its contents. Any uses or copies of this document in whole or in part must include the author's name.
JESSICAMARIALOPES.pdf (1.62 Mbytes)
Publishing Date
2018-05-29
 
WARNING: Learn what derived works are clicking here.
All rights of the thesis/dissertation are from the authors
CeTI-SC/STI
Digital Library of Theses and Dissertations of USP. Copyright © 2001-2024. All rights reserved.