Summary Incorporation of fatty acids into phospholipids has been investigated using samples of rat liver tissue homogenate, Krebs-Ringer-phosphate buffer (pH = 7.4) containing 0.3% albumin, fatty acid mixture and glyceroL The addition of L-kynurenine (4 nmol/g wet weight), D-eryhro-neopterin (5 and 30 pmol/g wet weight) and noradrenaline (4 nmol/g wet weight) to incubation medium induced an increase of saturated (palmitic acid) and decrease of poly-unsaturated (linoleic and arachidonic acid) fatty acids incorporation into phospholipids. The increase of saturated fatty acids incorporation into phospholipids was more pronounced after addition of neopterin and noradrenaline to the incubation medium while the decrease of linoleic and arachidonic acid synthesis was stimulated most with kynurenine. Moreover, kynurenine stimulated whereas neopterin depressed the oleic acid incorporation into phospholipids. These changes of fatty acid incorporation into phospholipids were followed by increase of cholesterol content in samples containing kynurenine, neopterin or noradrenalin. In contrast, phospholipid content decreased in samples containing kynurenine or noradrenalin, hut was not altered by supplementation of neopterin. Since the addition of kynurenine and neopterin to incubation medium for isolated fog heart resulted in an increased noradrenaline and decreased pyridoxal-5-phosphate content in the tissue, we also added pyridoxal-5-phosphate (4 nmol/g wet weight) to incubation medium for phospholipid biosynthesis. No change of the fatty acid incorporation into phospholipids as welI as the content of phospholipids and cholesterol in samples was observed.
Blockade of arachidonic acid incorporation into phospholipids induces apoptosis in U937 promonocytic cells