Cilostazol-induced PGI₂ production is dependent on IP3 receptor-mediated intracellular calcium elevation.

(A) Inhibitory effects of BAPTA-AM on cilostazol-induced PGI₂ production (n = 5; †† p < 0.01 vs. vehicle, t-test; ** p < 0.01 vs. 30 μM cilostazol alone, lower-tailed Williams’ test). (B) Effect of 2-APB on cilostazol-induced intracellular calcium levels. Fluo-4-loaded HAEC were pretreated with vehicle, 2-APB (100 μM), for 15 min and then cells were treated with cilostazol (30 μM, 50 s) followed by stimulation with ionomycin (1 μM). Data were normalized against the maximal intensity obtained with 1 μM ionomycin. (C) Inhibitory effect of 2-APB on cilostazol-induced PGI₂ production (n = 4; †† p < 0.01 vs. vehicle, t-test; ** p < 0.01 vs. 30 μM cilostazol, lower-tailed Williams’ test). (D) Effect of cilostazol (30 μM) on IP3 production (n = 4, †† p < 0.01 vs. vehicle, t-test).