Phosphatidylethanol formation and degradation in human and rat blood

Aims: To investigate the rate of formation and degradation of phosphatidylethanol (PEth) in rat blood as compared to human blood, as a model for a biological marker for ethanol exposure. Methods: Rats were given 9% ethanol in liquid diet for 30 days. Control rats were pair fed with a control liquid diet. Blood and organs were analysed considering PEth formed in vivo. Blood from man, rat, pig and ferret as well as human HepG2 cells and rat C6 glioma cells were studied with respect to formation and degradation of PEth in vitro. PEth was analysed by high performance liquid chromatography (HPLC). Results: Most rat organs accumulated considerable amounts of PEth whereas no PEth was found in the blood. After in vitro incubations of blood with ethanol, PEth was only formed by human blood, in contrast to the other species studied. HepG2 cells and C6 cells, like human blood, formed PEth in vitro but only the two cell lines had enzymatic degradation of PEth. Conclusions: The rat is not suitable as a model for assaying PEth in blood as a consequence of ethanol intake. Human blood seems to be particular in its ability to synthesize PEth and to maintain a stable level of PEth due to the lack of degrading activity.