In vitro studies of fatty acid metabolism in vitamin B6 deficient rats.

The oxidation of [1-14C]palmitate, [1-14C]linoleate, and [1-14C]arachidonate as well as their incorporation into lipids was investigated in vitamin B6 deficient rats using liver slices and isolated mitochondria. In experiments on fatty acid oxidation in liver slices, we observed a decrease in the production of 14CO2 from radioactive palmitate and linoleate, but not from arachidonate. In the case of mitochondria, we detected no difference between the deficient rats and the controls with linoleats; however, there was an increase in the oxidation of palmitate in the deficient rats as compared to the controls. Experiments on the incorporation of radioactivity into lipids showed an increase in radioactivity from [1-14C]palmitate and [1-14C]linoleate in the triglyceride, phospholipid and cholesterol fractions of deficient rats. In the case of [1-14C]arachidonate, no difference was observed between the two groups of rats. These experiments showed that major changes occurred in metabolism of palmitate and linoleate and strongly suggested that the decrease in the arachidonate content previously observed in rat tissues could not be explained by alteration in the metabolism of this fatty acid.

[Effect of pyridoxine deficiency on fatty acid metabolism in the rat]. / Influence d'une carence de pyridoxine sur le métabolisme des acides gras chez le rat.

We have studied the effect of pyridoxine deficiency on rat liver fatty acid synthetase using acetyl-1-14C-CoA. We have observed no significant difference in the synthetase activity between the deficient and ad libitum control rats. From in vivo experiments with palmitate-1-14C, linoleate-1-14C or arachidonate-1-14C, we noted an increase in the oxidation of all fatty acids in the deficient animals. Studies with the same tracers on their incorporation rate into liver triglycerides and phospholipids showed an increase in the rate of incorporation of palmitate and linoleate within lipids of deficient rats, but no significant difference was seen with arachidonate.

Effects of pyridoxine deficiency on the composition of plasma and liver fatty acids in rats fed low and high fat diets.

A study was made of the effect of pyridoxine deficiency on the fatty acids of liver and plasma in rats fed diets containing 1, 10, or 20% fat. Both ad libitum-fed and pair-fed control rats were used. In pyridoxine deficiency, arachidonic acid decreased with a concomitant increase in linoleic acid. Incubation of liver slices with [1-14C]acetate showed no significant alteration of fatty acid synthesis in pyridoxine-deficient rats fed 1 or 10% fat when compared with the ad libitum-fed control rats, but revealed a marked increase in cholesterogenesis compared with either control group. Incubations with [1-14C]linoleate resulted in no differences in the synthesis of arachidonate between the experimental and the ad libitum-fed control rats. Incubations with [5,6,8,9,11,12,14,15-3H]arachidonate showed decreased incorporation of this fatty acid in total liver lipids in pyridoxine-deficient rats compared with ad libitum fed control rats. We concluded that the diminution in arachidonate observed in liver lipids of pyridoxine-deficient rats does not result from a lower conversion of linoleate into arachidonate, but possibly from an increased degradation of this fatty acid.