The thiobarbituric acid reaction in relation to fatty livers

Abstract

Incubation of a rat liver homogenate ± Fe 2+ gave increased amounts of malonyl-dialdehyde (MDA) 2 for the thiobarbituric acid (TBA) reaction when the rats had previously received large doses of alcohol. Most of the MDA was derived from an in vitro oxidation of the fat which floated to the surface on centrifugation of an homogenate, and the magnitude of the TBA reaction varied with the amount of longchain unsaturated fatty acids in this fraction. The chronic administration of alcohol increased the TBA reaction only when the alcohol produced a fatty liver, and the latter varied with the amount of fat in the diet. Feeding orotic acid gave a fatty liver when the diet was fat-free, but such livers contained only small amounts of the longchain unsaturated fatty acids and formed less MDA on incubation than did the chow controls. Feeding orotic acid with a diet containing 21% of the calories as corn oil gave an equal fatty liver, but the TBA reaction and the long-chain unsaturated fatty acids in the liver were elevated. Hence, the alochol and orotic acid altered the TBA reaction in accordance with the amount of polyunsaturated fatty acids deposited in the liver, but the reaction was not a good quantitative measure of any tissue constituent.