Red blood cells attenuate sinusoidal endothelial cell injury by scavenging xanthine oxidase-dependent hydrogen peroxide in hyperoxic perfused rat liver.
OBJECTIVE
Rat liver perfused with an oxygenated buffered solution alone results in degenerative changes even when the perfusion flow is accelerated to give a sufficient oxygen supply. On the other hand, perfusion media supplemented with red blood cells (RBCs) preserve the viability of the liver. The present study was conducted to clarify how RBCs protect the isolated perfused liver.


METHODS
The liver was perfused with and without RBCs in a perfusate equilibrated with supra-physiological oxygen tension at regulated inflow pressures, and controlled hepatic oxygen consumption. We examined alanine aminotransferase and purine nucleoside phosphorylase activity in the perfusate as specific markers of liver cells injury. Hydrogen peroxide (H2O2) production and morphological changes were determined using cerium electron microscopy. Apoptosis was detected by measuring CPP 32 protease activity and using TdT-mediated dUTP-digoxigenin nick end-labeling.


RESULTS
When the liver was perfused with RBC-free buffer, H2O2 production and consequent injury progressing to apoptosis were initiated in the sinusoidal endothelial cells (SECs). After SECs were injured, H2O2 appeared in the hepatocytes. H2O2 production and associated degenerative changes were attenuated both morphologically and enzymatically by the addition of RBCs, a specific xanthine oxidase (XOD) inhibitor and the H2O2 radical scavenger, catalase.


CONCLUSIONS
In the liver perfused with RBC-free buffer, H2O2 production and consequent injury were initiated in SECs. RBCs attenuate liver injury by scavenging XOD-dependent H2O2.
Motoyama
S
S
Second Department of Surgery, Akita University School of Medicine, Hondo Akita City, Japan.
Saito
S
S
Inaba
H
H
Kitamura
M
M
Minamiya
Y
Y
Suzuki
H
H
Saito
R
R
Kamata
S
S
Nakae
H
H
Ogawa
J
J
D000410:Alanine Transaminase / Q000378:metabolism; D000818:Animals; D017209:Apoptosis; D001219:Aspartate Aminotransferases / Q000378:metabolism; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D015687:Cell Hypoxia; D004727:Endothelium / Q000187:drug effects / Q000201:enzymology* / Q000473:pathology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004912:Erythrocytes / Q000187:drug effects / Q000201:enzymology / Q000502:physiology*; D016166:Free Radical Scavengers; D006861:Hydrogen Peroxide / Q000378:metabolism*; D020287:In Situ Nick-End Labeling; D008099:Liver / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D008297:Male; D008928:Mitochondria / Q000201:enzymology; D023421:Models, Animal; D010477:Perfusion; D011683:Purine-Nucleoside Phosphorylase / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013047:Specific Pathogen-Free Organisms; D014227:Triazines / Q000494:pharmacology; D014969:Xanthine Oxidase / Q000037:antagonists & inhibitors / Q000378:metabolism*
D004791:Enzyme Inhibitors; D016166:Free Radical Scavengers; D014227:Triazines; C072977:BOF 4272; D006861:Hydrogen Peroxide; D014969:Xanthine Oxidase; D011683:Purine-Nucleoside Phosphorylase; D001219:Aspartate Aminotransferases; D000410:Alanine Transaminase; C505410:Casp3 protein, rat; D053148:Caspase 3; D020169:Caspases