Rhinocetin selectively inhibits collagen induced platelet activation.
A, the effect of 100 μg/ml of rhinocetin alone on human washed platelets was assessed by optical aggregometry along with 1 μg/ml of collagen as a positive control. B, various concentrations of rhinocetin were preincubated with human washed platelets before stimulating with 1 μg/ml of collagen and aggregation monitored for 90 s. C, the percentage inhibition of aggregation obtained with various concentrations of rhinocetin. The level of aggregation obtained with vehicle was taken as 100%. Data represent mean ± S.D. (n = 3). The effect of anti-integrin α2 antibody (6F1) (5 and 10 μg/ml) on collagen-induced (1 μg/ml) aggregation was assessed (D). The effect of 100 μg/ml of rhinocetin on 1 μg/ml CRP-XL- (E), 5 μm ADP- (F), 0.1 unit/ml thrombin-induced (G) and 5 μm TRAP1-induced (H) platelet activation using human washed platelets were also assessed. I, the effect of 100 μg/ml rhinocetin on 1.25 mg/ml ristocetin induced platelet agglutination using human platelet-rich plasma was analyzed. The traces are representative of three independent experiments. **, p < 0.01; ***, p < 0.001 as calculated by t test.