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Vol. 285, Issue 1, 155-161, April 1998
Department of Pediatrics, Division of Basic Sciences, National
Jewish Medical and Research Center, Denver, Colorado
The effects of ethanol and acetaldehyde on the metabolism of
leukotriene B4 (LTB4) and PGE2 were
investigated in isolated cultures of rat hepatocytes. LTB4
undergoes initial cytochrome P450-dependent
-oxidation leading to
the principal metabolites 20-hydroxy-LTB4,
20-carboxy-LTB4 and the
/
-oxidation product 18-carboxy-LTB4. The addition of low concentrations of
ethanol (25 mM) dramatically changes the relative amounts of these
metabolite products by inhibiting the alcohol dehydrogenase-mediated
oxidation of 20-hydroxy-LTB4. Addition of acetaldehyde to
the incubation, up to 1 mM, had no significant effect on overall
metabolism or distribution of metabolites. Above 1 mM acetaldehyde,
-oxidation of LTB4 was inhibited. Thus the effect of
ethanol on the metabolism of LTB4 appears to be due to
ethanol itself and not to secondary effects from the metabolic
transformation of ethanol to acetaldehyde in the cells.
PGE2 is metabolized in isolated rat hepatocytes to produce
chain-shortened products of
-oxidation characterized as
dinor-PGE1, dinor-PGE2,
tetranor-PGE1, tauro-dinor-PGE1 and tauro-dinor-PGE2. Low concentrations of ethanol (25 mM)
were found to increase the relative concentration of
dinor-PGE1 in the metabolic distribution, with a
corresponding decrease in concentration of tetranor-PGE1.
The amount of dinor-PGE2 that was produced remained relatively unchanged in response to increasing concentrations of
ethanol. Acetaldehyde concentrations from 0.1 mM to 1 mM did not affect
metabolite distribution or the overall magnitude of PGE2
metabolism. Concentrations of acetaldehyde higher than 1 mM decreased
all
-oxidation metabolites. Ethanol, at physiologically relevant
concentrations, could alter eicosanoid metabolism in the liver by
inhibiting LTB4 metabolism and altering that of
PGE2.
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