Changes in the free fatty acid composition of rat salivary glands induced by chronic administration of isoproterenol

The major constituent free fatty acid in rat parotid and submandibular glands was palmitic acid (about 40% of the total), followed by saturated and unsaturated fatty acids with 18 carbon atoms and arachidonic acid. The composition was changed by chronic administration of isoproterenol, with an increase of linoleic acid and a decrease of arachidonic acid coinciding with changes in the acyl composition of phospholipids. With respect to the metabolism of unsaturated fatty acids, delta 6-desaturation activity converting linoleic acid to gamma-linolenic acid was detected using [14C]linoleoyl-CoA in the submandibular gland. These results suggest that changes in the acyl composition of phospholipids induced by chronic administration of isoproterenol are in part due to changes in free fatty acid composition and that delta 6-desaturation activity may be involved in the regulation of unsaturated fatty acid composition.