Promutagen activation by freshly isolated and cryopreserved rat hepatocytes

Abstract
The metabolic activation of promutagens by freshly isolated and cryopreserved rat hepatocytes was compared using the Chinese hamster ovary/hypoxanthine‐guanine phosphoribosyltransferase assay (CHO/HGPRT). Cryopreserved rat hepatocytes were equivalent to freshly isolated hepatocytes in their ability to metabolize dimethylbenz(a)anthracene (DMBA) and dimethylnitrosamine (DMN) to active mutagens. Similar dose‐response curves were observed using either freshly isolated or cryopreserved hepatocytes as activating systems after treatment with DMBA (0.1‐1 μg/ml) and DMN (0.075‐0.6 mg/ml). Our results suggest that cryopreserved hepatocytes are similar to freshly isolated hepatocytes as an experimental system for studies on promutagen activation.