OxyFile #229

Endotoxin-induced hydrogen peroxide production in intact 
pulmonary circulation of rat.


Author:  Minamiya Y; Abo S; Kitamura M; Izumi K; Kimura Y;
         Tozawa K; Saito S

Source:  Am J Respir Crit Care Med 1995 Jul; 152(1):348-54

Abstract:

Although the importance of free oxygen radical has been 
reported in acute lung injury, the direct evidence in vivo 
model was lacking. We report a new method, which for the 
first time allows direct detection of hydrogen peroxide 
in the intact rat pulmonary microcirculation. We used the 
computer image-analyzing system and 2',7'-dichlorofluorescin 
diacetate for the marker of hydrogen peroxide production 
in vivo. A rat sepsis model was produced by continuous 
infusion of endotoxin for 30, 60, and 120 min. Hydrogen 
peroxide production in the pulmonary microcirculation of 
the sepsis rat was higher than in the control rat at each 
time point (p < 0.01) and increased time-dependently (p 
< 0.01). Catalase (5,000 U/kg) almost completely inhibited 
the hydrogen peroxide production in the sepsis rat (p < 
0.01). In high-power view, hydrogen peroxide was detected 
in granulocytes that adhered to the capillaries and endothelial 
cells that were adjoining adherent granulocytes. These 
observations suggest that hydrogen peroxide in the endothelium 
was diffused from granulocytes. In this study, we demonstrated 
direct evidence of hydrogen peroxide production from adherent 
granulocytes in intact rat lung treated with endotoxin. 
We conclude that endotoxin causes the granulocyte adhesion 
and oxidative stress to the endothelium due to adherent 
granulocytes within 30 min in the pulmonary microcirculation.