Effects of C18 Fatty Acids on Intracellular Ca2+ Mobilization and Histamine Release in RBL-2H3 Cells

To investigate the underlying mechanisms of C18 fatty acids (stearic acid, oleic acid, linoleic acid and alpha-linolenic acid) on mast cells, we measured the effect of C18 fatty acids on intracellular Ca2+ mobilization and histamine release in RBL-2H3 mast cells. Stearic acid rapidly increased initial peak of intracellular Ca2+ mobilization, whereas linoleic acid and alpha-linolenic acid gradually increased this mobilization. In the absence of extracellular Ca2+, stearic acid (100 mu M) did not cause any increase of intracellular Ca2+ mobilization. Both linoleic acid and alpha-linolenic acid increased intracellular Ca2+ mobilization, but the increase was smaller than that in the presence of extracellular Ca2+. These results suggest that C18 fatty acid-induced intracellular Ca2+ mobilization is mainly dependent on extracellular Ca2+ influx. Verapamil dose-dependently inhibited stearic acid-induced intracellular Ca2+ mobilization, but did not affect both linoleic acid-and alpha- linolenic acid-induced intracellular Ca2+ mobilization. These data suggest that the underlying mechanism of stearic acid, linoleic acid and alpha-linolenic acid on intracellular Ca2+ mobilization may differ. Linoleic acid and alpha-linolenic acid significantly increased histamine release. Linoleic acid (C18:2: omega -6)-induced intracellular Ca2+ mobilization and histamine release were more prominent than alpha-linolenic acid (C18:3: omega-3). These data support the view that the intake of more alpha-linolenic acid than linoleic acid is useful in preventing inflammation.