title: Cyclooxygenase--independent pathway of phospholipase activation in carrageenan--induced platelet aggregation.
abstract: Carrageenan induced aggregation and ATP release of washed rabbit platelets. The aggregation was resistant to indomethacin or creatine phosphate/creatine phosphokinase system but sensitive to mepacrine or p-bromophenacyl bromide. Chlorpromazine, verapamil or tetracaine inhibited carrageenan-induced aggregation, ATP release reaction and membrane-bound calcium redistribution in washed platelets. Agents elevating cyclic nucleotides selectively inhibited the release reaction without affecting the aggregation. The mechanism of carrageenan-mediated platelet responses may be due to both activation of phospholipases A2 and C. Platelet activating factor, protein kinase C and inositol triphosphate or phosphatidic acid could be mediated by carrageenan to accomplish the cyclooxygenase-independent events.
mesh_terms: D000818:Animals; D002118:Calcium / Q000037:antagonists & inhibitors / Q000502:physiology; D002351:Carrageenan / Q000494:pharmacology*; D002746:Chlorpromazine / Q000494:pharmacology; D004357:Drug Synergism; D004789:Enzyme Activation / Q000187:drug effects; D007213:Indomethacin / Q000494:pharmacology; D009599:Nitroprusside / Q000494:pharmacology; D010740:Phospholipases / Q000378:metabolism*; D010974:Platelet Aggregation / Q000187:drug effects*; D011451:Prostaglandin-Endoperoxide Synthases / Q000502:physiology*; D011817:Rabbits; D013748:Tetracaine / Q000494:pharmacology; D014700:Verapamil / Q000494:pharmacology
chemical_list: D013748:Tetracaine; D009599:Nitroprusside; D002351:Carrageenan; D014700:Verapamil; D011451:Prostaglandin-Endoperoxide Synthases; D010740:Phospholipases; D002118:Calcium; D002746:Chlorpromazine; D007213:Indomethacin