Oxygen consumption has been measured in sarcoma-bearing mice, liver cells and tumour tissue. The aim was to determine whether oxidative metabolism in tumour-host livers contributes to the negative energy balance in non-growing animals with a tumour due to insufficient hepatic adaptation of energy consumption. The oxygen uptake in isolated liver cells from freely fed and starved sarcoma-bearing mice showed a 50% decrease (depressed by 322 μmol O2/hr/g) compared to freely fed controls, while starvation of control animals reduced the oxygen uptake in the liver cells by 30-40%. In host tissues other than the liver, total oxygen uptake was depressed by an average 27% (depressed by 50 μmol O2/hr/g) 10-11 days after tumour implantation. In freely fed animals the ratio between oxygen uptake in the tumour-host liver and the host was 0.13 and 0.18 in sarcoma-bearing and control mice respectively. Depression of oxidative metabolism in tumour-host livers was not associated with ultrastructural alterations in the mitochondria or in other cellular organelles studied by electron microscopy. It is concluded that the negative energy balance in a non-growing tumour-bearing host is not explained by deficient adaptation of the hepatic oxidative metabolism, and that depression of activity metabolism in tumour-bearing animals accounts for depression of the metabolic rate in host tissues other than the liver.
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