Ionophore A-23187- and thrombin-induced platelet aggregation: independence from cycloxygenase products.
- 1 February 1978
- journal article
- research article
- Published by Proceedings of the National Academy of Sciences in Proceedings of the National Academy of Sciences
- Vol. 75 (2), 818-822
- https://doi.org/10.1073/pnas.75.2.818
Abstract
Stimulation of [horse] platelets labeled with [14C]-arachidonate by ionophore A23187 or thrombin produces rapid degradation of specific membrane phospholipids. This is also reflected by the release of [14C]arachidonate, which is immediately transformed into products of the cycloxygenase and lipoxygenase enzyme systems, and by increased labeling of phosphatidic acid. Arachidonate metabolism can be effectively prevented by preincubation with indomethacin and eicosatetraynoic acid, but platelet aggregation induced by ionophore A23187 or thrombin is not blocked under these conditions. Nevertheless, in the virtually total absence of metabolism of arachidonate, platelet aggregation still occurs concomitantly with phospholipid breakdown and with increased labeling of phosphatidic acid. Increased levels of cyclic[c]AMP block phospholipase activation and aggregation induced by ionophore A23187 and thrombin. Some early consequence of phospholipase activation, independent of a metabolic product of arachidonate but possibly related to the production of phosphatidic acid, may play a central, causative role in mediating platelet aggregation.This publication has 28 references indexed in Scilit:
- Interrelations of Platelet Aggregation and SecretionJCI Insight, 1977
- Carrageenan and thrombin trigger prostaglandin synthetase-independent aggregation of rabbit platelets: inhibition by phospholipase A2 inhibitorsJournal of Pharmacy and Pharmacology, 1977
- Cyclic adenosine 3',5'-monophosphate inhibits the availability of arachidonate to prostaglandin synthetase in human platelet suspensions.JCI Insight, 1977
- Initiation of phospholipase A2 activity in human platelets by the calcium ion ionophore A23187Biochimica et Biophysica Acta (BBA) - Lipids and Lipid Metabolism, 1977
- Rat platelets aggregate in the absence of endogenous precursors of prostaglandin endoperoxidesNature, 1976
- Identification of an enzyme in platelet microsomes which generates thromboxane A2 from prostaglandin endoperoxidesNature, 1976
- Metabolism of [14C]arachidonic acid by human plateletsBiochimica et Biophysica Acta (BBA) - Lipids and Lipid Metabolism, 1976
- Phospholipase A2 and its zymogen from porcine pancreas. VI. Histidine at the active site of phospholipase A2Biochemistry, 1974
- Effect of ADP-Induced Aggregation on32PO4Incorporation into Phosphatidic Acid and the Phosphoinoistides of Rabbit PlateletsBritish Journal of Haematology, 1973
- EFFECTS OF SALICYLATES ON HUMAN PLATELETSThe Lancet, 1968