Figure 3.

Inhibitory effect of Ir-CPI on generation of FXIIa, FXIa, and kallikrein in human plasma and on reconstituted systems. (A) Diluted human plasma was incubated with various concentrations of Ir-CPI (0.0625, 0.125, 0.25, 0.5, and 1 µM), and the mixture was activated with aPTT reagent to initiate the contact system. The amidolytic activities of generated FXIIa, FXIa, and kallikrein were determined by adding their specific chromogenic substrates and recording the increase in absorbance at 405 nm. (B–D) The effect of Ir-CPI was examined in reconstituted systems using purified factors and their specific chromogenic substrates. The activation of a nonactivated factor by an activated factor, in the presence or absence of Ir-CPI, was analyzed in each experiment. (B) Activation of prekallikrein into kallikrein by FXIIa. (C) Activation of FXI into FXIa by FXIIa. (D) Activation of FXII into FXIIa by FXIa Results are presented as the mean ± SEM of three independent determinations.