Metabolism of phenacetin in V79 Chinese hamster cell cultures expressing rat liver cytochrome P4501A2 compared to isolated rat hepatocytes

In a genetically engineered V79 cell line (XEMd-MZ) expressing rat cytochrome P4501A2 the activity of phenacetin-O-deethylase was determined and compared with freshly isolated rat hepatocytes. In the V79 cells the apparent Km was 0.99 microM (N = 4), compared to the high affinity Km (0.23 microM, N = 4) found in freshly isolated rat hepatocytes, where as the Vmax found in the XEMd-MZ cells (14.90 pmol/min/10(6) cells) corresponded to the Vmax for the high affinity site of the hepatocytes (18.2 pmol/min/10(-6) cells). The metabolic capacity of phenacetin was quantitatively comparable to that of freshly isolated hepatocytes on a cell to cell basis.