Although it has been over 100 years since Claude Bernard first reported the use of the isolated perfused rat liver (IPRL) (l), this model is still a valuable and commonly used tool for exploring the physiology and pathophysiology of the liver. Indeed, the IPRL remains an important experimental model despite the availability of newer techniques (e.g., liver slices, isolated and cultured cells, and isolated organelles) for evaluating hepatic function. This popularity is due to the fact that, in contrast to in uiuo models, such as the bile fistula rat, the IPRL allows repeated sampling of the perfusate, permits easy exposure of the liver to different concentrations of test substances and is amenable to alterations in temperature that would not be tolerated in uiuo. Furthermore, experiments can be done independent of the influence of other organ systems, plasma constituents and neural-hormonal effects. In contrast to other in uitro models, such as isoiated and cultured hepatocytes and isolated organelles, hepatic architecture, cell polarity and bile flow are preserved in the IPRL.
Given these considerations, it seems timely to update and, in a selective manner, to review the IPRL, especially as it relates to the study of hepatic function, the advantages and disadvantages of different technical aspects of the model and the problem of reliably assessing organ viability. This manuscript is intended not only to help the reader establish this model, but also to allow him to choose those conditions which best fit his particular needs. In addition, it will provide sufficient conceptual information to permit the reader to critically evaluate work with the IPRL. However, the manuscript is not meant to be a comprehensive technical review, as these are readily available (2). Rather, it is a highly selective update focusing on concepts, practical considerations and applications.