Arachidonate release and phosphatidic acid turnover in stimulated human platelets - PubMed (original) (raw)

. 1983 Feb 25;258(4):2461-7.

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Arachidonate release and phosphatidic acid turnover in stimulated human platelets

E J Neufeld et al. J Biol Chem. 1983.

Free article

Abstract

We have examined the temporal relationship between arachidonate release and phosphatidic acid (PA) metabolism in human platelets stimulated with thrombin. Within 1 min of stimulation at 37 degrees C, platelets released up to 16 nmol of arachidonate/10(9) cells from membrane phospholipids and exhibited an increase of severalfold in PA mass. At 23 degrees C, arachidonate release was half-maximal by 10-30 s, but PA remained near control levels for 10-30 s, indicating that increased PA is not necessary for release. [3H]Glycerol-labeled platelets synthesized phospholipids from [3H]PA at a rate of 0.08-0.3 nmol/min/10(9) cells at 37 degrees C. This rate of [3H]glycerol-PA turnover was not enhanced by thrombin stimulation; thus, PA did not turn over rapidly enough to be an intermediate in the release of several nanomoles of arachidonate from phosphatidylinositol in the first few seconds of stimulation. When aspirin-treated platelets were prelabeled with [14C]- or [3H]arachidonate, the specific activity of phospholipid-bound arachidonate pools remained constant after thrombin stimulation. Released arachidonate had specific activity intermediate to that in phosphatidylcholine and phosphatidylinositol. [14C]arachidonate in phosphatidylethanolamine had specific activity 6-fold less than released [14C]arachidonate; this phospholipid could therefore contribute only a small fraction of released fatty acid.

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