Data/hora: 11/06/2024 13:29:29

Provedor de dados: | 56
País: | Brazil
Título: | Antagonic effect of the inhibition of inducible nitric oxide on the mortality of mice acutely infected with Escherichia coli and Bacteroides fragilis
Autores: | Astolfi,R.S.; Khouri,D.G.; Brandizzi,L.I.V.; Ávila-Campos,M.J.; Andrade Jr.,H.F. de.
Data: | 2007-03-01
Ano: | 2007
Palavras-chave: | Nitric oxide; Sepsis; Experimental model; Bacterial infections; Escherichia coli; Bacteroides fragilis.
Resumo: | Sepsis, the leading cause of death in intensive care units, is associated with overproduction of nitric oxide (NO) due to inducible NO synthase (iNOS), responsible for some of the pathologic changes. Aminoguanidine (AG) is a selective iNOS inhibitor with reported inconsistent actions in sepsis. To investigate the influence of iNOS, we studied models of acute bacterial sepsis using acute challenges with aerobic (Escherichia coli) and anaerobic (Bacteroides fragilis) bacteria in the presence of AG. Six-week-old, 23 g, male and female BALB/c and C57Bl/6j mice, in equal proportions, were inoculated (ip) with bacteria in groups of 4 animals for each dose and each experiment in the absence or presence of AG (50 mg/kg, ip, starting 24 h before challenge and daily until day 6) and serum nitrate was measured by chemiluminescence. Both types of bacteria were lethal to mice, with an LD50 of 6 nephelometric units (U) for E. coli and 8 U for B. fragilis. Nitrate production peaked on the second day after E. coli inoculation with 8 and 6 U (P &lt; 0.05), but was absent after non-lethal lower doses. After challenge with B. fragilis this early peak occurred at all tested doses after 24 h, including non-lethal ones (P &lt; 0.05). AG-treated mice challenged with E. coli presented higher survival (P &lt; 0.05) and increased LD50. AG-treated mice challenged with B. fragilis had lower LD50 and higher mortality. Control AG-treated animals presented no toxic effects. The opposite effect of iNOS blockade by AG in these models could be explained by restriction of oxygen for immune cells or an efficient action of NO in anaerobic localized infections. The antagonic role of NO production observed in our bacterial models could explain the reported discrepancy of NO action in sepsis.
Tipo: | Info:eu-repo/semantics/other
Idioma: | Inglês
Identificador: | http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2007000300006
Editor: | Associação Brasileira de Divulgação Científica
Relação: | 10.1590/S0100-879X2006005000078
Formato: | text/html
Fonte: | Brazilian Journal of Medical and Biological Research  v.40 n.3 2007
Fonte: | info:eu-repo/semantics/openAccess