Oxygen supply and uptake in the liver and the intestine.

The oxygen supply to the liver was found to be dependent on the total blood flow only and not on the ratio of arterial to portal contribution. The mean value of O2-uptake in the liver, related to a blood flow of 110 ml/min - 100 g liver, amounted to 6.08 +/- 0.2 ml O2/min - 100 g liver (mean +/- S.E.M.). O2-uptake of the intestine was found to be 1.95 +/- 0.13 ml O2/min - 100 g tissue, related to a normal blood flow of 50 ml/min - 100 g tissue. With low oxygen supply O2 extraction in the liver reaches values of 97%, whereas the intestinal extraction does not surpass 75%. A rise in oxygen supply surmounting normal values does not increase the O2-consumption. Contrary to the intestinal circulation the liver showed no postocclusive vasodilatation. The oxygen debt was payed back by a greater extraction. The portal oxygen supply to the liver can markedly increase due to intestinal metabolic hyperemia. High O2-extraction capacity, rather than vasodilatation, is the main mechanism for matching hepatic oxygen supply with requirements. The hepatic venous blood may leave the liver with an extremely low O2-content.