The effects of ethanol and diet on hepatic and serum gamma-glutamyltranspeptidase activities in rats.

Rats fed pelleted nonpurified diets had significantly higher hepatic gamma-glutamyltranspeptidase (GGTP) activities than those fed liquid diets, with no difference in serum GGTP activities. However, levels of both hepatic and serum GGTP activity were higher in rats fed ethanol than in those fed liquid diets without ethanol. In addition, hepatic GGTP levels varied inversely with dietary carbohydrate content. These findings suggest that factors other than a mere increase of liver GGTP may be responsible for the elevated serum levels of this enzyme seen after chronic ethanol consumption and that dietary carbohydrate levels influence hepatic GGTP levels.