Fig. 2.
(A) The inhibitory effect of crude saponin fraction (CSF) on collagen-induced [Ca2+]i. Washed platelets (3 × 108/mL) were incubated with a calcium fluorophore (5 μM; Fura-2-acetoxymethyl ester) and stimulated with collagen (2.5 μg/mL). [Ca2+]i was then measured as described in the “Materials and Methods” section. (B) Effects of CSF on granule secretion from the collagen-stimulated platelets. Washed platelets (3 × 108/mL) were preincubated with CSF at the indicated concentrations and stirred in an aggregometer for 2 min before stimulation with 2.5 μg/mL collagen for 5 min. The reaction was terminated, and adenosine triphosphate (ATP) release was determined by ATP assay. Assay was performed as described in the “Materials and Methods” section. Bar graphs show the mean ± standard deviation of at least four independent experiments. * p < 0.05, ** p < 0.005, *** p < 0.001 compared with the agonist control. Coll, collagen.