Absorptive-excretory function of isolated dog liver during its perfusion]

Twenty experiments were performed on mongrel dogs. The absorptive and excretory function of the liver in the intact organism and during its isolated perfusion through the portal vein with the use of extracorporeal circulation was studied by means of the bromsulfaline test. The absorptive function of the perfused liver proved to decrease by 50-60 per cent. The rate of bile elimination and plasma clearance was 5-6 times higher at the beginning of the experiment in the intact organism. Later on, the difference in the degree of retention of the hepatic excretory function was reduced. Hypoxia connected with denervation, hepatectomy and the isolated perfusion proper apparently served as the principal cause of reduction of the absorptive-excretory function of the isolated liver.     

Metabolism of chylomicrons by the isolated rat liver

Isolated livers perfused with washed corn oil chylomicrons labeled in vivo with palmitic acid-1-(14)C removed a large proportion of the chylomicrons. Slices from these livers oxidized chylomicron fatty acid esters to both carbon dioxide and acetoacetate. The liver slices also generated free fatty acids from chylomicron lipids and converted chylomicron triglycerides to phospholipids. Similar activities were observed in rat liver slices prepared shortly after the intravenous administration of chylomicrons to intact rats. The observed chylomicron uptake and lipid conversions were similar in livers from both fed and fasted rats. Fasting increased the oxidation of chylomicron fatty acid esters by livers labeled in vivo and by perfusion. In livers removed from intact rats given labeled chylomicrons, the triglyceride-(14)C to phospholipid-(14)C ratio was high, a finding unexpected if the liver had acquired this (14)C by removal of circulating fatty acids formed by extrahepatic lipolysis. These results demonstrate the ability of the liver to remove and utilize chylomicrons directly and suggest that direct removal accounts for a significant portion of the chylomicron fatty acids utilized by the liver of intact rats.