Heterogeneity in the rate of benzo[a]pyrene metabolism in single cells: quantitation using flow cytometry.
We describe a method for quantitating heterogeneity in the rate of benzo[a]pyrene metabolism in single cells by using flow cytometry. We have used the technique to study the response of Hepa-1c1c7 mouse hepatoma cells to the microsomal enzyme inducer 2,3,7,8-tetrachlorodibenzo-p-dioxin. Cells responded in a relatively homogeneous fashion at different times of induction with a maximally inducing concentration of the inducer. However, the induction response could be heterogeneous at a submaximal inducer concentration. We found even higher heterogeneity of enzyme activity among low-activity variants derived from the Hepa-1c1c7 cell line. When cells of either high or low activity were isolated from such a clonal population, propagated, and reanalyzed, they displayed average enzyme activity and heterogeneity identical to the parental cells; therefore, the heterogeneity represents transient, nonheritable differences between cells within the population.
Department of Pharmacology, Stanford University School of Medicine, Stanford, California 94305, USA.
A G
AG
Miller
J P
JP
Whitlock
D000818:Animals; D001564:Benzo(a)pyrene / Q000737:chemistry / Q000378:metabolism*; D001711:Biotransformation; D002455:Cell Division / Q000187:drug effects; D045744:Cell Line, Tumor; D004790:Enzyme Induction / Q000187:drug effects; D005434:Flow Cytometry / Q000379:methods*; D007700:Kinetics; D051379:Mice; D000072317:Polychlorinated Dibenzodioxins / Q000494:pharmacology
D000072317:Polychlorinated Dibenzodioxins; D001564:Benzo(a)pyrene