In this study, we focused on the antimicrobial effect of NO
against V. harveyi infection in the hepatopancreas of L. vannamei.
We studied the kinetics and dose-dependent effects of NO killing of
V. harveyi by using NOC-18, a highly stable chemical donor that
releases NO in aqueous solutions without requiring co-factors and
without producing toxic metabolites [23]. We also monitored the
changes of hepatopancreatic NO/nitrite concentration and NOS
mRNA level after V. harveyi challenge. Furthermore, the effects of an
established mammalian cell-permeable NOS inhibitor (L-NAME,
which have Ki values of 15 nM, 39 nM, and 4.4 mM for nNOS, eNOS
and iNOS, respectively [24], and can be hydrolyzed into the fully
functional inhibitor, L-NNA, by cellular esterases [25]) on bacterially
induced-NO/nitrite production and V. harveyi survival were
examined.