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Infect. Immun., May 1997, 1767-1772, Vol 65, No. 5
S Sriskandan, D Moyes, LK Buttery, J Wilkinson, TJ Evans, J Polak and J Cohen
Nitric oxide (NO) produced by inducible NO synthase (iNOS) mediates
hypotension in endotoxemia. In this study, NO induction by a toxin-
producing Streptococcus pyogenes isolate, H250, and by recombinant
streptococcal pyrogenic exotoxin A (rSPEA) has been examined, both in vitro
and in vivo. Streptococcal supernatants, but not rSPEA, induce production
of nitrite by murine macrophages when both are coincubated with gamma
interferon. Intraperitoneal injection of rSPEA did not cause significant
production of NO. However, an elevated level of nitrate in serum was
detected in a model of streptococcal fasciitis due to live H250. iNOS was
localized to Kupffer cells, hepatocytes, and renal tubular cells by
immunostaining. Administration of a NOS inhibitor,
N(G)-monomethyl-L-arginine (L-NMMA), reduced peak concentrations of nitrate
in serum but did not affect survival. NO is induced by H250, both in vitro
and in vivo, mainly via SPEA-independent mechanisms. In this model, iNOS is
expressed predominantly in the liver. Furthermore, in this model L-NMMA is
not protective.
Copyright © 1997, American Society for Microbiology
The role of nitric oxide in experimental murine sepsis due to pyrogenic exotoxin A-producing Streptococcus pyogenes
Department of Infectious Diseases, Royal Postgraduate Medical School, Hammersmith Hospital, London, United Kingdom.
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