The effects of light exposure on the in vitro hepatic response to an amino acid-vitamin solution

Background: Administration of parenteral nutrition (PN) that has been irradiated with light is associated with hepatic dysfunction in rats in vivo. Using the isolated perfused rat liver, we report the in vitro hepatic response to a light-exposed amino acid-vitamin (AAV) solution, compared with a light-protected solution. Methods: The amino acid-vitamin solution (3 g Aminosyn and 2.5 mL MVI-12 added to buffer) was placed under a lamp in a beaker that was covered completely with foil (light-protected) or with a transparent wrap (light-exposed) for 24 hours before liver perfusion. Livers from adult male rats were isolated and perfused with buffer for 30 minutes, with the AAV solution for 60 minutes, and again with buffer for 30 minutes. Results: Infusion with the AAV solution resulted in decreases in bile flow rates. Compared with light-protected groups, light-exposure was associated with significantly lower bile flow rates, significant increases in biliary concentrations of oxidized glutathione (GSSG), and significantly decreased biliary concentrations of free amino acids, including the glutathione precursors glutamate and glycine. Conclusions: Perfusion of the isolated rat liver with an AAV solution that has been irradiated with light for 24 hours results in a decrease in bile flow rates and an increase in biliary GSSG concentrations, suggesting oxidant stress. Consideration should be given to protecting solutions from light in the clinical selling.