Open AccessContribution of phospholipases A 2 and D to arachidonic acid liberation and prostaglandin D 2 formation with increase in intracellular Ca 2+ concentration in rat peritoneal mast cells
Author(s) -
ISHIMOTO Tsuyoshi,
AKIBA Satoshi,
SATO Takashi,
FUJII Tatsuzo
Publication year - 1994
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1994.tb19952.x
Subject(s) - liberation , arachidonic acid , ionomycin , chemistry , phosphatidylethanol , phosphatidic acid , histamine , phospholipase a2 , phosphatidate , extracellular , protein kinase c , biochemistry , endocrinology , biology , diacylglycerol kinase , intracellular , enzyme , phospholipid , membrane , in vitro
The contribution of phospholipases A 2 (PLA 2 ) and D (PLD) activation to arachidonic acid liberation and prostaglandin D 2 (PGD 2 ) formation was studied in stimulated rat peritoneal mast cells. Stimulation of the cells with ionomycin induced time‐dependent and Ca 2+ ‐concentration‐dependent increase in arachidonic acid liberation and PGD 2 formation, and the Ca 2+ ‐dependent increase was especially remarkable at extracellular Ca 2+ concentration higher than 200 μM. Staurosporine did not induce any effect on the arachidonic acid liberation, indicating that protein kinase C is not involved in the liberation. Addition of ethanol to the cells decreased the ionomycin‐stimulated arachidonic acid liberation to 40% of the control, while it decreased the PGD 2 formation almost completely, with the increase in phosphatidylethanol formation. Propranolol, a phosphatidate phosphohydrolase inhibitor, caused similar effects. p ‐Bromophenacyl bromide, a PLA 2 inhibitor, inhibited partially the arachidonic acid liberation. The inhibition of the liberation by combination of p ‐bromophenacyl bromide and ethanol was additive and reached approximately 90%. Under the conditions used p ‐bromophenacyl bromide did not influence significantly the PLD activity assessed by the phosphatidylethanol formation. Histamine release was decreased by ethanol treatment to 35% of the control. These results suggest that more than half of the total arachidonic acid liberation is mediated by the sequential pathway of PLD/phosphatidate phosphohydrolase/diacylglycerol lipase and more than half of histamine release is also dependent on PLD activation, while the PGD 2 formation is fully mediated by the pathway. PLA 2 also contributes to arachidonic acid liberation but to a lower extent.