Utilisation of Amino Acids by the Perfused Rat Liver

Abstract

Amino acid metabolism has been studied in the perfused rat liver, with a perfusate containing glucose, a mixture of glycerol, lactate and pyruvate, and amino acids at relative concentrations resembling those in normal rats. Most amino acids were utilised by the liver, despite the excess carbohydrate. Branched-chain acids were not released, except in the absence of added amino acids. This finding, and measurements of urea production, suggested that lysis of endogenous protein was not marked. In starved or diabetic rats, utilisation of most amino acids and lysis of endogenous protein was enhanced. During perfusion without added amino acids, a range of amino acids were released into the perfusate, from livers of fed rats, but not from livers of diabetic or starved rats. These results are discussed in terms of the influence of carbohydrate fuels upon amino acid metabolism.