Model of TPN-associated hepatobiliary dysfunction in the young pig

Gallbladder 'sludge' and cholestasis are two common complications associated with total parenteral nutrition (TPN), but the aetiology of each is uncertain. An animal model has been developed in the young pig which demonstrates these two complications. Five female piglets, of Landrace Large White Cross variety weighing 4.5-5.9 kg, received nutritional support for 2 weeks with a continuous infusion of TPN solution at a dose of 150 kcal kg-1 day-1. The solution was 35 per cent dextrose, 5 per cent L-amino acids with conventional electrolyte, mineral and vitamin additives. No lipid was used in the solution. Five weight-matched animals were used as controls. All animals in the TPN group developed 'sludge' in their gallbladders, decreased basal bile flow, decreased bile salt excretion and a diminished response to bile salt stimulated bile flow, as compared with controls. There was no abnormality in routine liver function tests or liver histology. It is concluded that TPN therapy in this animal model is associated with the appearance of gallbladder 'sludge', and cholestasis as demonstrated by direct bile flow studies. It is suggested that this bile flow abnormality is due to a decrease in bile salt dependent and bile salt independent fractions of canalicular bile flow. The model provides the opportunity to investigate TPN related hepatobiliary dysfunction in an animal that has similar liver function to man and comparable nutritional requirements.