A possible role of pyridoxine in lipid metabolism.

The influence of pyridoxine upon the metabolic conversion of linoleic acid to arachidonic acid was studied in the livers of rats maintained w ith different kinds and conditions of dietary fats. In the basal diet group, the liver phospholipid fraction of the pyridoxine deficient animals revealed significantly higher percentage of linoleic acid and significantly lower percentage of arachidohic acid, when compared with the control group, whereas in the liver phospholipid fraction, the proportion of arachidonic acid was higher and that of eicosatrienoic acid significantly lower in the pyridoxine deficient group fed the hardening oil diet. Recovery experiments were carried out. The time course of changes in the fatty acid composition of the liver lipids of rats fed cotton-seed oil, after 6 weeks on a hardening oil diet, revealed slower velocity of increase in arachidonate, slower velocity of decrease in eicosatrienoate and faster velocity of increase in linoleate in the pyridoxine deficient group. Changes in the fatty acid composition of the liver phospholipid after giving r-linolenate to rats previously fed a fat free diet showed also slower velocity of increase in arachidonate and lower velocity of decrease in eicosatrienoate. It is concluded that pyridoxine plays an important role in the essentia l fatty acid metabolism, chiefly in the conversion of r-linolena te to arachidonate.