In all these situations proper assessment of liver viability is essential and it is generally agreed that the rates of oxygen consumption and bile production are two simple but reliable guides. However, because of the multiplicity and complexity of liver cell functions, a more extensive assessment is usually desirable, and a large variety of liver-function tests have been used for this purpose. These include the clearance of bromsulphalein (B.S.P.) (Chapman, Goldsworthy, Nyhus, Volwiler, and Harkins, 1960), the clearance of ammonia (Eiseman, Knipe, Koh, Normell, and Spencer, 1963), and the clearance of lactate and pyruvate (Schimassek, 1965); the rate of synthesis of glycogen from glucose (Craig, 1966); the synthesis of urea from ammonia (Hems, Ross, Berry, and Krebs, 1966); the rate of elimination of galactose (Tengstrom, 1966); the rate of glucose oxidation (Sicular and Moore, 1961); and the rate of uptake of potassium (Flink, Hastings, and Lowry, 1950).
Unfortunately, conflicting views are held with regard to the value of some of these tests. Drapanas, Zemel, and Vang (1966) have stated that the clearance of ammonia, B.S.P., and bilirubin can be carried out readily by even the dying liver, whereas Van Wyk and Eiseman (1966) have used these same liverfunction tests as criteria of liver viability.
We first developed a successful technique for the prolonged perfusion of an isolated pig liver. This technique was then used in a series of twelve perfusions in order to assess the value and limitations of some of the above liver-function tests and to study the changes in liver viability during perfusion as a function of time.
Methods
The animals used were large white pigs weighing 60-80 lb. All animals were fed on glucose and vitamin-E supplements for 36 hours before operation. The pigs were anaesthetized with halothane, nitrous oxide, and oxygen, via a tracheostomy. The external jugular vein and the carotid artery were cannulated for administering intravenous glucose * Read at a meeting of the Surgical Research Society, January, 1968.