Biphasic modulation of platelet phospholipase A2 activity and platelet aggregation by mepacrine (quinacrine).
The modulation of rat platelet phospholipase A2 (phosphatide 2-acylhydrolase, EC 3.1.1.4) and rat platelet aggregation by mepacrine was investigated. The 2-acyl specificity of phospholipase A2 activity was confirmed by using 1-[14C]palmitoyl-2-[3H]arachidonylphosphatidylcholine as substrate. Under optimal pH, phospholipase A2 activity was not affected by aspirin but was inhibited by indomethacin. Contrary to previous reports, a biphasic modulatory role of mepacrine on phospholipase A2 activity and platelet aggregation was demonstrated. The data suggest that platelet aggregation is mediated via phospholipase A2.
D000818:Animals; D001241:Aspirin / Q000494:pharmacology; D001792:Blood Platelets / Q000201:enzymology*; D004305:Dose-Response Relationship, Drug; D007213:Indomethacin / Q000494:pharmacology; D008297:Male; D010740:Phospholipases / Q000097:blood*; D010741:Phospholipases A / Q000037:antagonists & inhibitors / Q000097:blood*; D054467:Phospholipases A2; D010974:Platelet Aggregation / Q000187:drug effects*; D011796:Quinacrine / Q000494:pharmacology*; D051381:Rats; D013379:Substrate Specificity
D010740:Phospholipases; D010741:Phospholipases A; D054467:Phospholipases A2; D011796:Quinacrine; D001241:Aspirin; D007213:Indomethacin