Flow microfluorometric identification of liver cells with elevated gamma-glutamyltranspeptidase activity after carcinogen exposure.
We have developed a fluorometric cytochemical assay for gamma-glutamyltranspeptidase (gamma-GT) using the substrate gamma-glutamyl-4-methoxy-2-naphthylamide in which the released methoxynaphthylamine was coupled with 5-nitrosalicylaldehyde to form a yellow fluorescent crystalline product within the cells. Single cell suspensions were obtained by collagenase perfusion of livers from rats that had either received a two-thirds partial hepatectomy followed 24 hr later by a single injection of diethylnitrosamine (DEN) or received a partial hepatectomy alone. Cultured HTC cells were used as a source of gamma-GT+ cells. Fluorescence (gamma-GT activity) was low in most of the cells from both DEN-exposed and control rats, but high in HTC cells. The livers of both DEN-exposed and control rats had a subpopulation of cells that were gamma-GT+; this population could be quantitated and sorted by flow cytometry. Five weeks post injection the number of GT+ cells from the rats exposed to DEN was more than 20 times that from the control rats. Increased gamma-GT activity may be a useful cytochemical marker for preneoplastic liver cells.
D000818:Animals; D006528:Carcinoma, Hepatocellular; D002460:Cell Line; D004052:Diethylnitrosamine / Q000494:pharmacology*; D005260:Female; D006651:Histocytochemistry; D008099:Liver / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology; D008113:Liver Neoplasms; D009602:Nitrosamines / Q000494:pharmacology*; D051381:Rats; D013050:Spectrometry, Fluorescence; D005723:gamma-Glutamyltransferase / Q000032:analysis*
D009602:Nitrosamines; D004052:Diethylnitrosamine; D005723:gamma-Glutamyltransferase