Figure 3.

Plasma TFPI activities. (A) TFPI activities were measured in plasma from mice that contain a floxed TFPI-K1 domain and either do not express Cre recombinase (TFPI^Flox) or express the Cre recombinase via the endothelial specific promoter for Tie2 (TFPI^Tie2) or the myelomonocytic specific promoter for LysM (TFPI^LysM). Animals that express Cre recombinase have a TFPI K1 domain deletion, which is the domain necessary for TFPI inhibition of the TF coagulation pathway. TFPI^Tie2 mice have significantly reduced circulating TFPI activity levels compared with TFPI^Flox (*P < .001) and TFPI^LysM mice (†P < .001). The TFPI^LysM mice have significantly lower circulating TFPI activities than TFPI^Flox littermate controls (*P < .001; panel A). (B) Heparin infusion fails to increase plasma TFPI activity in TFPI^Tie2 mice.