nitrophenols and Starvation

Conditions leading to the accumulation of unconjugated phenols and catechols were investigated in mouse livers. The formation of unconjugated hydroxylated products of added p-nitrophenol and aniline was investigated in isolated hepatocytes prepared from 48 hr fasted or fed mice or from fed mice after acetone pretreatment. 4-Nitrocatechol and p-aminophenol--the hydroxylated products of p-nitrophenol and aniline--were accumulated in cells prepared from fasting animals, while in cells prepared from fed mice these unconjugated derivatives were not detectable. The accumulation of 4-nitrocatechol and p-aminophenol was also shown in isolated hepatocytes prepared from acetone pretreated fed mice. Inhibition of glucuronidation by N6,O2-dibutyryl cAMP or by D-galactosamine increased the accumulation of 4-nitrocatechol upon addition of p-nitrophenol in cells prepared from fasted mice. Both 48 hr starvation and acetone pretreatment enhanced the activity of microsomal p-nitrophenol and aniline hydroxylase by 300% and 600%, respectively, whereas p-nitrophenol conjugation in isolated hepatocytes as well as in hepatocyte homogenates was decreased by about 80% after 48 hr starvation. Acetone pretreatment did not alter the rate of p-nitrophenol conjugation measured in liver homogenates. It is suggested that a shift from conjugation toward hydroxylation in starvation gives rise to the formation of hazardous metabolites.

Topics: Acetone; Aniline Compounds; Animals; Catechols; Cells, Cultured; In Vitro Techniques; Liver; Mice; Nitrophenols; Phenols; Starvation

Acid phosphatase activity is demonstrated employing p-nitrophenyl phosphate as substrate and lead acetate as coupler. The fine structural localization of the enzyme in starved planarian tissues is described. The method is used to pin-point starvation - induced acid phosphatase activity in relation to autophagy and crinophagy in the gland cells; autophagy, autolysis and cell death in parenchymal and gastrodermal cells and basement membrane lysis. Attention is also payed to the demonstration of muscle lysis. The histochemical implications of the method are discussed.

Topics: 4-Nitrophenylphosphatase; Acid Phosphatase; Animals; Basement Membrane; Histocytochemistry; Microscopy, Electron; Nitrophenols; Phosphoric Monoester Hydrolases; Planarians; Staining and Labeling; Starvation; Turbellaria

The effect of a 3-day period of complete starvation on the hepatic UDPglucuronosyltransferase activity was studied in the rat. The substrate specificity of the enzyme was assayed with bilirubin as a carboxylic acceptor, and phenolphthalein and p-nitrophenol as phenolic acceptors. Starvation increased the bilirubin UDPglucuronosyltransferase specific activity by 33%, whereas no increase in specific activities appeared when the phenolic substrates were used. However, on a total liver weight basis, all three activities were significantly lower than those of the controls. Kinetic studies of activated microsomal bilirubin UDPglucuronosyltransferase showed that apparent Km values were similar; fasting acted only by increasing V. The results suggest that the changes in bilirubin glucoronosyltransferase activity provoked by starvation may reflect actual enzyme induction; they favour the multiplicity of the UDPglucuronosyltransferase system.

Topics: Animals; Bilirubin; Glucuronosyltransferase; Hexosyltransferases; Kinetics; Liver; Male; Microsomes, Liver; Nitrophenols; Organ Size; Phenolphthaleins; Rats; Starvation

Topics: Biochemical Phenomena; Hypoxia; Nitrophenols; Oxygen; Phosphorylation; Starvation