Spin Trapping Studies of Alcohol-Initiated Radicals in Rat Liver: Influence of Dietary Fat

Abstract

We conducted spin trapping experiments to test the effects of acute and chronic alcohol consumption in livers from rats that had been fed either high fat (35% of energy) or low fat (12% of energy) liquid diets. Rats were anesthetized with isoflurane, the spin trapping agent POBN [α-(4-pyridyl-1-oxide)-N-t-butylnitrone] was administered by intravenous injection, and bile samples were collected for electron paramagnetic resonance (EPR) analyses. Two different types of EPR spectra were observed in bile from the animals in these studies. One set of spectral lines was from the 1-hydroxyethyl radical adduct of POBN, which was conclusively identified by injecting the rats with [1-13C]ethanol. The EPR signals of a second type of radical adduct in bile could be observed both before and after acute administration of ethanol. Although the radical(s) responsible for this second series of signals could not be conclusively identified, it is likely that lipid radicals were formed under these conditions and trapped by POBN. For both types of radical adducts, the most intense EPR signals were observed in rats that had been fed alcohol in combination with a high fat diet for 2 wk before the experiments. These results confirm and extend previous data indicating that high levels of dietary fat enhance alcohol-associated free radical formation in the liver.