FORMATION OF PROSTANOIDS AND HYDROXY FATTY-ACIDS BY STIMULATED PERITONEAL MAST-CELLS - ROLE OF THE DIETARY-FAT TYPE IN RAT

To study the influence of membrane fatty acid composition on the forma tion of prostanoids and hydroxy fatty acids by rat peritoneal mast cel ls (MC), animals were fed three different types of fatty acids: macker el oil (MO), abundant in n - 3 fatty acids; sunflower seed oil (SO), r ich in linoleic acid; and hydrogenated coconut oil (HCO), mainly conta ining saturated fatty acids. The presence of n - 3 fatty acids in the diet resulted in the incorporation of 20: 5(n - 3), 22: 5(n - 3) and 2 2: 6(n - 3) in MC phospholipids. A decrease of arachidonic acid, 20:4( n - 6), was observed in MC-phospholipids of the MO-fed animals. Furthe rmore, increasing the relative amounts of 18:2(n - 6) in the diet (SO group) led to an increased incorporation of linoleic acid, 18:2(n - 6) in MC phospholipids when compared to both other dietary groups. The c hanges in MC phospholipid fatty acid composition were (partly) reflect ed in the formation of prostanoids and hydroxy fatty acids upon stimul ation with the calcium ionophore A23187. The decrease in arachidonic a cid content in MC phospholipids of MO-fed rats resulted in a decreased formation of PGD2 when compared to both other groups. Also, the incre ased amounts of 18:2(n - 6) in MC phospholipids of SO-fed rats resulte d in an increased formation of 9-and 13-HODE upon stimulation. The res ults show that modifications in the fatty acid composition of the diet influences MC membrane fatty acid composition which ultimately result s in changes in prostanoid and hydroxy fatty acid synthesis by MC upon stimulation with the calcium ionophore A23187.