M. Suematsu et al., MICROVASCULAR OXIDATIVE STRESS PRECEDING LEUKOCYTE ACTIVATION ELICITED BY IN-VIVO NITRIC-OXIDE SUPPRESSION, The American journal of physiology, 266(6), 1994, pp. 80002410-80002415
This study was aimed to determine the mechanism by which endogenous ni
tric oxide supression promotes leukocyte adhesion in vivo. The rat mes
enteric microcirculation was superfused with NG-nitro-Larginine methyl
ester (L-NAME; 100 mu M), and intracellular oxidant formation in seve
ral microcirculatory cellular components such as arteriolar and venula
r endothelium and mast cells was visually monitored by digital microfl
uorography assisted by carboxydichlorofluorescein (CDCF), a hydroperox
ide-sensitive fluorogenic probe. Adherent leukocyte density was measur
ed simultaneously. L-NAME induced a significant time-dependent increas
e in CDCF fluorescence in arteriolar and venular endothelium and mast
cells followed by firm adhesion of leukocytes. L-NAME-induced CDCF ele
vation showed a different spatial distribution compared with that evok
ed by N-formylmethionyl-leucyl-phenylalanine, in which only local venu
lar segments with adhering leukocytes exhibited CDCF fluorescence enha
ncement. The level of hydroperoxide formation in arterioles and venule
s evoked by 60-min L-NAME superfusion was equivalent to that induced b
y the superfusion of similar to 880 mu M tert-butyl hydroperoxide for
10 min. Pretreatment with anti-intracellular adhesion molecule-1, anti
-P-selectin, or anti-CD18 monoclonal antibody attenuated L-NAME-elicit
ed venular leukocyte adhesion without abolishing CDCF fluorescence in
situ. Pretreatment with desferioxamine (50 mg/kg iv; 1 h before L-NAME
superfusion) significantly diminished the iron-catalyzed hydroperoxid
e formation in arterioles and venules, but not in interstitial mast ce
lls, as well as subsequent venular leukocyte adhesion. These findings
indicate that endogenous nitric oxide may modulate oxidative stress in
mast cells, arteriolar and venular microvascular endothelium and ther
eby can play a crucial role in leukocyte recruitment in venules.