The influence of the position of the oxygen dissociation curve on oxygen-dependent functions of the isolated perfused rat liver

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Abstract
The influence of a 2,3-diphosphoglycerate (2,3-DPG)-induced displacement of the oxygen dissociation curve (O.D.C.) on the isolated perfused rat liver was studied at different levels of anaemic hypoxia. Rat livers were perfused either with fresh or with 2,3-DPG-depleted human erythrocytes at different haematocrit values (from 30% to 2.5%) at constantP O 2 of the inflowing perfusate and at constant blood flow rate. The 2,3-DPG-induced difference in oxygen affinity of the red cells did not cause a significant difference in perfusion pressure during the perfusion experiments. Therefore, there is no evidence that 2,3-DPG did alter the vascular resistance of the liver, since blood flow rate could be adjusted at equal values. The decrease in oxygen supply brought about by decrease of haematocrit caused a decrease of O2 consumption, of bile flow rate and of venousP O 2 and an increase of lactate/pyruvate (L/P) ratio and of β-hydroxybutyrate/acetoacetate (βOH/Acac) ratio. There was no influence of a difference in 2,3-DPG content of the erythrocytes on the above-mentioned parameters during severe anaemic hypoxia. At moderate anaemic hypoxia the venousP O 2 was higher during perfusion with fresh erythrocytes than during perfusion with 2,3-DPG-depleted erythrocytes. Thus, although 2,3-DPG may play a compensatory role during conditions of mild anaemia, no such effects can be observed during conditions of severe hypoxia.