Comparative effects of UW and SLS solutions on concentrative proline uptake in cold preserved rat hepatocytes

In previous studies, we have shown that the rate of cell swelling induced by concentrative proline uptake in isolated rat hepatocytes decreased by 50 per cent after only 24 h of cold storage in University of Wisconsin (UW) solution, thereby representing a sensitive marker of alterations in hepatocyte functions after cold preservation and rewarming. We have thus used concentrative proline uptake to compare the capacity of UW and sodium-lactobionate-sucrose (SLS) solutions to maintain such differentiated hepatocyte functions. Isolated rat hepatocytes were kept at 4 degrees C for 4, 10, 24 and 48 h in UW or SLS solutions, and subsequently cultured at 37 degrees C for 1-2 h. Viability was measured by Trypan blue exclusion. After rewarming, cells were subjected to a 10 min administration of 10 mM proline and accumulation of the amino acid was assessed by changes in cell volume as measured by digital analysis of single-cell images obtained under bright-field illumination. Cell viability was reduced gradually and significantly after 0 to 48 h of preservation, and rewarming amplified this effect. However, loss of viability was similar in UW- and SLS-stored cells, as were initial steady-state cell volumes. Proline-induced swelling rate was reduced significantly by 13, 46 and by 57 per cent after 10, 24 and 48 h of preservation in UW solution, respectively. There is no significant difference between SLS- and UW-preserved hepatocyte swelling rates after 10 h and 48 h of cold preservation. However, the decline in the swelling rate of SLS-preserved hepatocytes incubated for 24 h is significantly lower than that of their UW-preserved counterparts. These results show that the SLS solution can preserve differentiated hepatic functions as well as the UW solution does.