Rabbit hepatocytes in primary culture: preparation, viability and use in studies of propranolol metabolism.

Isolated hepatocyte cultures have become a frequently used model system for investigating drug metabolism. Although rat and hamster hepatocytes are frequently used for this purpose, metabolism in these species differs in many respects from human metabolism. A species with a metabolism more closely resembling that of humans might be more useful. Our in vivo experiments demonstrated that the metabolism of propranolol in the rabbit is more similar to that in humans than in rats or hamsters. We therefore examined the usefulness of rabbit parenchymal liver cells for studies of propranolol metabolism. A detailed method is presented for their preparation and culture, along with data on their viability, structure and protein synthesizing capability. One- or two-day-old hepatocyte cultures were exposed to 10 mumol/L 3H-propranolol from 30 min to 2 hr; metabolites were identified by gas chromatography-mass spectrometry and quantitated by high-performance liquid chromatography. Propranolol metabolism was linear over 1 hr, with 15% of the substrate metabolized during this time. The cytochrome P-450 pathways, which result in ring oxidation and side-chain oxidation, were expressed in a reproducible fashion similar to that found in vivo in humans. The arylhydrocarbon hydroxylase inhibitor alpha-naphthoflavone (100 mumol/L) inhibited side-chain oxidation of propranolol by 90% without affecting ring oxidation. In contrast, chlorpromazine (100 mumol/L) was shown to inhibit ring oxidation of propranolol by 85% without affecting side-chain oxidation. Cimetidine (250 mumol/L) inhibited both pathways by about 50%.(ABSTRACT TRUNCATED AT 250 WORDS)