The activities of the cytosolic, microsomal and mitochondrial γ-glutamyl transpeptidase(γ-GTP) and leucine aminopeptidase(LAP) in the liver were measured in order to evaluate the biochemical back ground, especially the enzymological background
of
endotoxin toxicity. And the activities of these enzymes in the serum were also measured.
For administration of endotoxin, a dose of 5mg of endotoxin(lipopolysaccharide E. coli O26: B6, from Sigma, USA) per kg of body weight was administered through a right external jugular vein. Then the rats were killed after 3, 8 and 24 hours of
injection
with endotoxin to measure the activities of the above enzymes in serum and their livers.
Cyrtosolic γ-GTP activity showed a significant increase at 8 hours after endotoxin administration. Microsomal γ-GTP activity showed a significant decrease between 3 and 8 hours after endotoxin administration. The activity of the mitochondrial
γ-GTP
in the liver showed no significant changes throughout the experiment.
Cytosolic LAP activity showed a significant decrease between 8 and 24 hours after endotoxin administration. The activities of microsomal PAP and mitochondrial LAP in the liver showed no significant changes throughout the experiment.
Serum γ-GTP activity showed a significant increase between 3 and 8 hours after endotoxin administration. The activity of serum LAP showed a significant decrease at 3 hours after endotoxin administration.
According to the results, it is suggested that microsomal γ-GTP flows into the serum through the damaged membrane and the biosynthesis of this enzyme is decreased, and changes of the serum γ-GTP and LAP activities are due to leak into the blood
through the damaged membrane of hopatocyte.
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