VOL. 4 (1950) 



METABOLIC RATE OF THE LIVER 



323 



30 



60 



90 120 



time in win 



Fig. I. Spontaneous changes in oxygen 

 consumption during artificial perfusion 



of a cat liver (• •) and a hind limb 



preparation (x x). 



i 



6 

 E 4 



.S 



5 3 



is shown in Fig. i. The oxygen uptake has been followed by frequent photoelectric 

 determinations of the oxygen content in the venous blood. The galvanometer readings 

 in each experiment have been standardized by .s 5 

 at least 4 determinations of the venous oxygen ^ 

 content by the Van Slyke technique. Care has ^ 4 

 been taken to obtain, as great differences be- 5 

 tween the oxygen content in the samples used g 3 

 for the standardization as possible. The oxygen g" 

 content in the arterial blood was determined 2 

 with the Van Slyke technique at the beginning 

 and at the end of the experimental period and in ' 

 some experiments also in the middle of this 

 period. Though the initial pronounced decrease in 

 oxygen consumption is only observed in experi- 

 ments with isolated livers it can not of course be 

 ruled out that this decrease might be due to an 

 impairment of the circulation in the liver or 

 some other damage developing during the first 



period after the isolation of the organ. The question whether it is possible to restore the 

 oxygen uptake after it has attained its low and rather constant level must be of 

 decisive importance for the evaluation of the phenomenon. 



On the assumption that the decrease in oxygen consumption is due to a disappear- 

 ance of some substance present in fresh blood but gradually used up by the liver the 

 simplest way to try to restore the oxygen uptake would be to renew the blood after 

 the drop in oxygen uptake has developed. The result of such a simple experiment is 

 shown in Fig. 2. As is seen the addition of fresh blood to the perfusion apparatus causes 

 a marked but transitory increase in the oxygen uptake. A quantitative comparison 

 between the increase obtained by adding fresh blood and the initial drop in oxygen 

 uptake is difficult since it is not possible to renew the blood in the apparatus completely. 

 It is only possible to remove some of the blood and add some fresh blood. In this way 



not more than about 50% renewal of the blood 

 is obtained. As some change in the cell volume 

 of the perfusion blood resulting from the addi- 

 tion of fresh blood cannot be avoided, and as 

 this alters the standardization of the galvano- 

 meter readings care has been taken to draw 

 simultaneously a sample of arterial and venous 

 blood for Van Slyke determinations as near as 

 possible to the "peak" as judged from the gal- 

 vanometer readings. In this way the magnitude 

 of the increase in the neighbourhood of the maxi- 

 mum is ascertained by the Van Slyke technique. 

 In some experiments blood used for the per- 

 fusion of a liver for one to one and a half hours 

 has been used for perfusion of an other freshly 

 prepared liver. In these experiments the oxygen uptake of the second liver was low 

 from the start of the perfusion and remained low. 

 References p. 329. 



30 



60 



90 120 



time in min 



Fig. 2. Oxygen uptake of isolated cat 



liver, between > and < perfusion blood 



partly exchanged with fresh blood. 



