322 BIOCHIMICA ET BIOPHYSICA ACTA VOL. 4 (1950) 



OBSERVATIONS ON A FACTOR DETERMINING THE 

 METABOLIC RATE OF THE LIVER 



by 



EINAR LUNDSGAARD 



Institute of Medical Physiology, University of Copenhagen {Denmark) 



In a paper published some years ago^ brief mention was made of experiments on 

 isolated, artificially perfused livers in which the rate of oxygen uptake in the liver was 

 consistently found to decrease during the first 30-45 minutes after the liver had been 

 isolated. This phenomenon has intrigued me ever since, and although the cause of this 

 drop in metabolic rate in a liver isolated from the "periphery" is not ascertained a short 

 appraisal of the experience gained so far may be presented. 



Most of the experiments have been carried out on cat livers. The metabolism of 

 the isolated cat liver is peculiar in that carbohydrates are not metabolized^. The respira- 

 tory quotient of the isolated cat liver is always very low — generally below 0.7. The 

 blood sugar concentration never decreases. Irrespectively of the blood sugar level a 

 steady increase in blood sugar concentration is observed. This increase must be due to 

 a gluconeogenesis as it is observed also in livers in which the glycogen store has been 

 exhausted by starvation. It appears most likely that the lack of carbohydrate metabo- 

 lism in the isolated cat liver is not an artefact but a characteristic feature in the liver 

 metabolism of this species. Nevertheless one might claim that a liver which does not 

 metabolize carbohydrate must be in an abnormal state and that the drop in metabolic 

 rate might have some connection with this abnormal state. Contrary to the cat liver 

 the isolated rabbit liver, however, stores glucose as glykogen and oxidizes carbohydrate 

 and although my experience with the rate of oxygen consumption in the isolated rabbit 

 liver is far more limited than my expeiience with cat livers it can safely be stated that 

 in the isolated rabbit liver also a drop in metabolic rate is encountered immediately 

 after isolation. 



It might well be questioned whether any importance can be attached to a drop in 

 metabolic rate in an organ kept alive by artificial perfusion. Such a view appears justi- 

 fied, however, since such a decline in oxygen uptake is observed in experiments on livers 

 only and not in experiments on other organs. In the — unfortunately unsuccessful — 

 endeavour to make preparations of isolated cat intestines function normally with respect 

 to absorption a considerable number of experiments have been carried out in which 

 the oxygen uptake of the isolated cat intestine was determined. The oxygen consumption 

 of such a preparation always remains constant. In perfusing experiments on hind limb 

 preparations the oxygen uptake always increases markedly. This increase generally 

 continues for the entire experimental period of two hours which is the time most often 

 used in my experiments. The marked difference between the changes in oxygen uptake 

 in a typical experiment on a liver preparation as compared with a hind limb preparation 



References p. 32 g. 



