Fig. 2.

Cucurbitacin B, E and I inhibit integrin αIIbβ3 activation but not α granule secretion. Washed human platelets were pre-treated with increasing concentrations of cucurbitacin B, E or I (0.1–10 µM) prior to stimulation with either ( A ) cross-linked collagen-related peptide (CRP-XL) (1 µg/mL), ( B ) thrombin receptor-activating peptide-6 (TRAP-6) (1 µM) or ( C ) adenosine diphosphate (ADP) (10 µM) and α granule secretion determined by monitoring P-selectin exposure (grey) and integrin activation measured as fibrinogen binding (black) determined using flow cytometry, quantified data shown. ( D ) Washed human platelets were pre-treated with cucurbitacin B, E or I (10 µM) prior to stimulation with TRAP-6 (1 µM) and (i) dense granule secretion determined by monitoring CD63 surface expression via flow cytometry and (ii) release of soluble α granule contents determined by measuring platelet factor 4 (PF4) levels of the platelet releasate by Western blotting, quantified data shown. Results are mean + standard error of the mean (SEM) for n ≥ 3, * indicates p  < 0.05 in comparison to vehicle controls, where normalised data shown, statistics were performed prior to normalisation.