Isolated hepatocytes are a valuable tool to study liver functions. Suitable methods to preserve the isolated cells with good maintenance of viability and functions are crucial to extend experiments with hepatocytes from a single isolation over 2 or more consecutive days. We investigated whether University of Wisconsin (UW) solution, which was designed to preserve organs for transplantation, is also suitable for preservation of isolated rat hepatocytes. Viability, as determined by Trypan blue exclusion and reduction of the tetrazolium 3(4,5-dimethyl-thiazoyl-2-yl)2,5 diphenyltetrazolium bromide to a purple formazan, morphological appearance using electron microscopy, ATP levels and uptake and storage of three model drugs ([3H]vecuronium, [3H]taurocholic acid and [3H]ouabain) were determined directly after isolation and after 22 hr of storage in UW solution at 0-4 degrees. The present study shows that cold storage of rat hepatocytes for 22 hr in UW can be performed without significant loss of viability and with maintenance of proper morphology, cellular ATP and transport functions. In contrast, after storage in Krebs-Henseleit buffer the normal morphology, ATP content and transport functions were strongly affected. These results imply that hepatocytes from a single isolation and stored in UW solution can be used for experiments on 2 consecutive days.