Effect of GIRK channel blockers on AA-induced TXA₂ generation. Washed non–aspirin-treated human platelets were stimulated with AA (100 μM) for 3.5 minutes at 37°C under stirring conditions in the presence of SQ29548 (10 μM), in the presence and absence of SCH23390 (10 μM), U50488H (10 μM), or SKF38393 (10 μM). Reactions were stopped after 3.5 minutes and TXB₂ levels were analyzed as described in “Materials and methods.” The data are represented as the percent maximal TXB₂ generated by AA obtained in the absence of antagonists. Each bar is the average of 3 experiments ± SEM from 3 different donors.