Long-chain fatty acid uptake and oxidation in the perfused liver of Walker-256 tumour-bearing rats.
OBJECTIVE
The effect of the Walker-256 tumour on uptake and oxidation of long-chain fatty acids was investigated in perfused livers of rats.


METHODS
Isolated livers were perfused in a non-recirculating system. Fatty acid uptake, ketogenesis, oxygen uptake and 14CO2-production were measured as well as the activities of the acyl carnitine transferases I and II (CAT I and CAT II).


RESULTS
Basal oxygen uptake of livers from tumour-bearing rats was lower. Ketone bodies production derived from the long-chain fatty acids in livers from starved tumour-bearing rats was lower relative to the controls, but 14CO2 production was similar in both groups. The oxygen uptake increment and the mitochondrial NADH/NAD+ redox ratio were also decreased in tumour-bearing rats. The extent of these differences was dependent on the chain length and structure of the fatty acid, the following decreasing sequence of differences between control and tumour-bearing animals being valid: palmitate > oleate > stearate. The CAT I activity of the enzyme isolated from livers of tumour-bearing rats was half that from normal rats when palmitoyl-CoA and oleoyl-CoA were the substrates.


CONCLUSIONS
Ketogenesis from exogenous fatty acids is decreased in the livers of Walker-256 tumour-bearing rats in consequence of the diminished activity of the mitochondrial CAT I. The lower rates of oxygen uptake indicate a decreased ATP synthesis, which is consistent with the in vivo lower phosphorylation potential.
Vicentino
Christiame
C
Laboratory of Liver Metabolism, University of Maringá, 87020900 Maringá, Brazil.
Constantin
Jorgete
J
Bracht
Adelar
A
Yamamoto
Nair Seiko
NS
D000818:Animals; D002245:Carbon Dioxide / Q000378:metabolism; D002279:Carcinoma 256, Walker; D002334:Carnitine O-Palmitoyltransferase / Q000378:metabolism; D005227:Fatty Acids / Q000378:metabolism*; D066298:In Vitro Techniques; D007657:Ketone Bodies / Q000096:biosynthesis; D008099:Liver / Q000378:metabolism*; D008297:Male; D019301:Oleic Acid / Q000378:metabolism*; D010084:Oxidation-Reduction; D010101:Oxygen Consumption; D010168:Palmitates / Q000378:metabolism*; D010477:Perfusion; D051381:Rats; D017208:Rats, Wistar; D013228:Stearates / Q000378:metabolism*
D005227:Fatty Acids; D007657:Ketone Bodies; D010168:Palmitates; D013228:Stearates; D002245:Carbon Dioxide; D019301:Oleic Acid; D002334:Carnitine O-Palmitoyltransferase