Formation of phosphatidylethanol in frozen kidneys from ethanol-treated rats

We recently identified phosphatidylethanol (Pet) in tissues from ethanol-treated rats. Since phosphatidyl esters are formed artefactually during freezing in plants we wanted to examine if PE was elevated during freezing in animal tissues. Rats were treated with 3 g/kg of ethanol, killed after 3 h and PE was isolated from kidneys at once or after storage at 0, -5, -10, -15, -20 and -80 degrees C for 7 days. Kidneys analyzed at once or after storage at -80 degrees C had Pet equivalent to 0.02 mumol Pet/g. Storage at -10 degrees C and -15 degrees C resulted in increases of Pet to 1.5 mumol Pet/g and 1.2 mumol Pet/g, respectively. Thus, Pet is artefactually elevated during storage of tissues from ethanol-treated rats at lower freezing temperatures, reflecting considerable changes in composition of acidic phospholipids.