EFFECTS OF LIGHT-EXPOSED PARENTERAL-NUTRITION ON HEPATIC-FUNCTION ANDLIDOCAINE METABOLISM - A STUDY USING ISOLATED RAT-LIVER PERFUSION

Effects of light-exposed parenteral solutions on hepatic function and lidocaine metabolism were studied. Male rats (190-220 g) were randomly assigned to one of the three isocaloric treatment groups: parenteral nutrition (PN)(+L) group (n = 6), animals received a solution of 24.2% dextrose and 5.2% amino acids with light exposure; PN(-L) group (n = 5), animals received the same solution without light exposure; and CF group, chow-fed animals (n = 6) that received rat chow and water. Aver age energy intake in these animals was similar to 33 kcal/100 g/d. Lid ocaine metabolism was studied in livers isolated from animals 7 d afte r treatment. Liver morphology indicated that five livers from PN(+L) a nimals developed steatosis. The lidocaine metabolism rate was the slow est in PN(+L) animals; this is marked by changes in the steady state l evels (% dose) of lidocaine [PN(+L), 47.9 +/- 17.6; PN(-L), 25.9 +/- 2 .1; versus CF, 11.3 +/- 5.3; p < 0.05]. The extraction ratio and intri nsic clearance values were reduced by 41 and 86% in PN(+L) group and 1 6 and 70% in PN(-L) group, respectively, when compared with CF (p < 0. 05). Metabolite to drug ratios indicated that N-dealkylation, ring-hyd roxylation, and aryl methyl hydroxylation of lidocaine were severely i mpaired, particularly in the PN(+L) animals. The extents of reduction in metabolic pathways were in the ranges 79-95% in the PN(+L) group an d 44-90% in the PN(-L) (p < 0.05). These findings suggest that parente ral nutrition infusion induces steatosis and reduces the rate of lidoc aine metabolism and exposure of parenteral nutrition solutions to ligh t exacerbates this change.