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Phosphatidic acid with medium-length fatty acyl chains synergistically stimulates phospholipase C with Ca2+ in rabbit
1Department of Biochemistry, Kyoto Pharmaceutical University, Japan.
Abstract:
The mode of phospholipase C activation in platelet cells induced by didecanoyl (C10)-phosphatidic acid (PA) was investigated with washed rabbit platelets. The C10-PA dose-dependently induced aggregation and serotonin secretion, as well as increases in cytoplasmic free Ca2+ concentration and 1,2-diacylglycerol formation. None of these responses was evoked unless Ca2+ had been added to the platelet suspension. Furthermore, under the conditions of various intracellular Ca2+ concentrations which were set by treatment of the cells with ionomycin and Ca2+, C10-PA promoted 1,2-diacylglycerol formation only at the Ca2+ concentration of 300 nM or higher, whereas thrombin induced the formation even at 100 nM Ca2+. These results suggest that PA activates platelet phospholipase C in cooperation with Ca2+ and contributes to platelet activation through such an effect.