Effect of perfusate albumin on organ viability and vascular responses in the in vitro dual-perfused rat liver Wenxuan Yang a , Irving S. Benjamin a , Roy Sherwood b , Jonathan Salisbury c , Barry Alexander a, * a Liver Sciences Unit, Academic Department of Surgery, St. Thomas Hospital, Lambeth Palace Road, London SE1 7EH, UK b Department of Clinical Biochemistry, King's College Hospital, Bessemer Road, London SE5 9PJ, UK c Department of Histopathology, King's College Hospital, Bessemer Road, London SE5 9PJ, UK Received 21 June 2000; received in revised form 19 August 2000; accepted 7 September 2000 Abstract Inclusion of albumin in the perfusate has been previously shown to be detrimental to liver function, but its effect on hepatic vascular reactivity remains unknown. The aim of this study was to determine the effects of albumin on hepatic arterial vascular reactivity and liver viability in the isolated dual-perfused rat liver. A total of 12 rat livers were perfused with Krebs± Bu Èlbring buffer without (Group 1) and with (Group 2) addition of 1% bovine serum albumin (BSA) through the hepatic artery and portal vein for up to 5 h. Hepatic arterial responses to acetylcholine and sodium nitroprusside were studied at 30-min intervals. Liver viability was assessed by bile volume production, release of aspartate serine aminotransferase (AST) and lactic acid dehydrogenase (LDH), and histological examination. Hepatic arterial responses to acetylcholine were significantly attenuated in Group 2. No significant differences in sodium nitroprusside responses were noted. However, bile volume production in Group 2 was significantly decreased compared to Group 1. Effluent AST and LDH release increased significantly in Group 1 but not in Group 2. Histological results showed that sinusoidal endothelial cells and hepatocytes were well preserved without significant deterioration in either group, although there was a marked decrease in vasodilatation to acetylcholine in Group 2. This data suggested that the presence of albumin in the perfusate did not improve retention of smooth muscle reactivity and reduced endothelium-dependent vasodilatation and bile volume production during perfusion. However, improved liver parenchymal cell function was observed. D 2001 Elsevier Science Inc. All rights reserved. Keywords: Rat liver; Perfusate; Albumin; Endothelium response; Liver viability 1. Introduction Isolated perfused rat livers have been used extensively to investigate the mechanisms of hepatic metabolism (Alex- ander, 1998), the control of vascular tone (Yang, Benjamin, & Alexander, 1995), and the viability of preserved livers prior to transplantation (Imamura, Brault, & Huet, 1997; Ontell et al., 1988). Krebs ± Henseleit buffer supplemented with glucose, albumin, and taurocholic acid has been pre- viously used as the standard perfusate for many studies (Gores, Kost, & Larusso, 1986; Ontell et al., 1988; Wolkoff, Johansen, & Goeser, 1987). In addition, some investigators add erythrocytes to the perfusate to improve its oxygen- carrying capacity (Wolkoff et al., 1987), but this may compound data interpretation in pharmacological studies since these may allow release of vasoactive agents (Berg- field & Forrester, 1992). Krebs±Bu Èlbring buffer has been widely used in our laboratory for rabbit (Alexander, Mathie, Ralevic, & Burn- stock, 1992) and rat (Alexander, Aslam, & Benjamin, 1995; Yang, Benjamin, & Alexander, 1999) liver perfu- sions without addition of albumin or erythrocytes. Although the oxygen-carrying capacity of the perfusate used is relatively poor compared to erythrocyte-supplemen- ted perfusates (Alexander, Aslam, & Benjamin, 1998), pharmacological data suggest that this may be unimportant in relation to hepatic vascular responses during perfusion of up to 5 h (Alexander, Browse, & Benjamin, 1999; Browse, Benjamin, & Alexander, 1994; Yang, Benjamin, & Alexander, 1997, 1999). Furthermore, it has been suggested that addition of erythrocytes, glucose, albumin, * Corresponding author. Liver Science Unit, The Rayne Institute, King's College London, 123 Coldharbour Lane, London SE5 7EH, UK. Tel.: +44-171-928-9292 ext. 2877; fax: +44-171-928-8742. E-mail address: barry.alexander@kcl.ac.uk (B. Alexander). Journal of Pharmacological and Toxicological Methods 43 (2000) 225± 231 1056-8719/00/$ ± see front matter D 2001 Elsevier Science Inc. All rights reserved. PII:S1056-8719(00)00106-4