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Infect. Immun., 06 1997, 2074-2079, Vol 65, No. 6
V Martin, AL Kleschyov, JP Klein and A Beretz
The cardiovascular dysfunctions associated with septic shock induced by
gram-negative or gram-positive bacteria (gram-positive or gram-negative
septic shock) are comparable. In gram-negative septic shock,
lipopolysaccharide (LPS) induces nitric oxide (NO) synthase, which
contributes to the vascular hypotension and hyporeactivity to
vasoconstrictors. The role of NO in gram-positive septic shock and the
nature of the bacterial wall components responsible for the vascular
effects of gram-positive bacteria are not well known. This study
investigated the vascular effects of cell wall serotype polyosides,
rhamnose glucose polymers (RGPs), from Streptococcus mutans, in comparison
with lipoteichoic acid (LTA) from Staphylococcus aureus, on the induction
of NO synthase activity in the rat aorta. We show that 10 microg of both
RGPs and LTA per ml induced hyporeactivity to noradrenaline,
L-arginine-induced relaxation, increases of 2.2- and 7.8- fold,
respectively, of cyclic GMP production, and increases of 7- and 12-fold in
nitrite release. All of these effects appeared after several hours of
incubation and were inhibited by N(omega)-nitro-L-arginine methyl ester
(L-NAME), an inhibitor of NO synthase. Electron paramagnetic resonance spin
trapping experiments demonstrated directly that RGPs and LTA induced NO
overproduction (four- to eightfold, respectively) in rat aortic rings; this
production was inhibited by L- NAME and prevented by dexamethasone. These
results demonstrate directly the induction of NO production in vascular
tissue by LTA and show that another, chemically different component of
gram-positive bacteria can also have these properties. This result suggests
that different components of the gram-positive bacterial wall could be
implicated in the genesis of cardiovascular dysfunctions observed in
gram-positive septic shock.
Copyright © 1997, American Society for Microbiology
Induction of nitric oxide production by polyosides from the cell walls of Streptococcus mutans OMZ 175, a gram-positive bacterium, in the rat aorta
Laboratoire de Pharmacologie et de Physiopathologie Cellulaires, URA CNRS 600, Faculte de Pharmacie, Universite Louis Pasteur de Strasbourg, France.
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