The influence of the position of the oxygen dissociation curve on oxygen-dependent functions of the isolated perfused rat liver. II. Studies at different levels of hypoxia induced by decrease of blood flow rate.

Abstract

The influence of the 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 stagnant hypoxia (hypoxia induced by decrease of blood flow rate at constant PO2 and at constant haematocrit). Rat livers were perfused with a medium containing either fresh or 2,3-DPG-depleted erythrocytes (2,3-DPG content: 4.3 +/- 0.4 and 0.6 +/- 0.4 mmol/l erythrocytes, respectively). The difference in oxygen affinity of the red cells did not affect the vascular resistance of the perfused liver tissue. The decrease in oxygen supply brought about by a decrease in blood flow rate resulted in a decrease of bile flow rate and of oxygen consumption. The higher 2,3-DPG content of the fresh erythrocytes was reflected in a higher bile flow rate at all blood flow levels, in a higher oxygen consumption at lower blood flow levels, and in a higher venous PO2 at the higher blood flow levels. Venous PO2, lactate/pyruvate (L/P) ratio and beta-hydroxybutyrate/acetoacetate (betaOH/Acac) ratio were relatively insensitive to stagnant hypoxia and to a difference in the 2,3-DPG content of the erythrocytes. The ATP content of the liver tissue was decreased at the lower blood flow levels. However, the ATP content of the livers perfused with fresh erythrocytes did not differ from that of the livers perfused with 2,3-DPG-depleted erythrocytes.