Relationship beteen activation of "detoxicating" enzymes in stored broken-cell preparations and in autolysing liver

Abstract

Activity of UDP-glucuronyltransferase (GT) towards o-aminophenol, p-nitrophenol and bilirubin has been followed in portions of mouse liver stored for periods up to 24 h and in mouse-liver homogenates stored under similar conditions of time and temperature. In both preparations and for all three substrates the pattern of change of GT activity was closely similar. Activity decreased initially, then rose to an optimum higher than in fresh tissue before finally falling. Overall glucuronidation, as measured in slices, also follwed this pattern. The effect of cycloheximide and of detergents, and the levels of UDP-glucose dehydrogenase, UDP-glucuronic acid and aniline hydroxylase were also studied. It is concluded that autolysing liver tissue passes through a period of increased GT activity and glucuronidation corresponding in onset with spontaneous activation of GT in stored homogenates and probably originating by a similiar mechanism. This increase contrasts with progressive fall in hydroxylating activity. The latency of GT in vivo and the value of its activation in damaged liver are discussed.