In vivo biliary function in the adult rat: The effect of parenteral glucose and amino acids

Parenteral glucose and glucose-amino acid mixtures are used in the nutritional support of infants, children, and adults when enteral feedings are precluded for any reason. During the first week of such nutritional support, the total energy intakes are generally low and glucose and electrolytes are the only nutrients provided. To assess the effects of such 'hypocaloric' regimens, we determined the hepatic responses to parenteral infusions of either glucose or glucose-amino acid mixtures in rats. Further, to illustrate the magnitude of these changes in comparison to normally fed animals, we included a group of sham-operated, chow-fed rats. Bile flow, biliary bile acid output, bile osmolarity, serum bile acids, and plasma amino acids were measured in adult rats following 5 days of the respective dietary regimens. Liver histology was also assessed. Bile acid output, but not bile flow, was significantly decreased by the infusion of glucose compared to glucose-amino acid mixtures. However, in comparison to the chow-fed rats, bile acid output was significantly reduced in both groups of parenterally fed animals, whereas bile flow was significantly reduced only in the glucose-infused animals. Plasma amino acids were markedly different between the groups; concentrations of essential amino acids were greater in the glucose-amino acid infused animals than in the glucose infused animals. Nonessential gluconeogenic amino acids were significantly higher in the glucose-infused animals compared to the other groups; plasma valine was significantly lower in the glucose-infused animals reflecting the lack of protein intake. Liver histology was markedly abnormal in all of the glucose-infused animals, whereas only half the glucose-amino acid infused animals had abnormal pathology. Our data indicate that adverse effects on hepatic function are induced by the infusion of glucose alone in the rat; further, the addition of amino acids to the infusion of glucose appears to decrease some of these adverse effects. Data in sham-operated, chow-fed animals indicate the magnitude of change in hepatic function due to the parenteral infusions. We hypothesize that the use of glucose and electrolytes alone for extended periods of time prior to the introduction of amino acids may increase the possibility of hepatic dysfunction in response to parenteral nutrition.