Blood and plasma viscosity of wt and tg mice. (A) Blood viscosity from wt (109 ± 6 days old) or tg (111 ± 9 days old) mice was measured at predefined shear rates ranging from 2 s^–1 to 450 s^–1. Transgenic blood (▦; hematocrit value, 0.88) was about 4 times as viscous as normal wt blood (□; hematocrit value, 0.43) but only half as viscous as hemoconcentrated wt blood reaching an hematocrit value of 0.89 (▪). Due to the extreme viscosity of the concentrated wt blood its viscosity at the highest shear rate could not be determined with our viscosimeter (missing black column at 450 s^–1). The viscosity of reconstituted blood consisting of wt erythrocytes in tg plasma (▧) or tg erythrocytes in wt plasma (), both adjusted to an hematocrit value of 0.44, did not differ from that of normal wt blood. Although in tendency the viscosity of tg erythrocytes in wt plasma was slightly lower than wt erythrocytes in tg plasma, this observation was significant only at 5 s^–1 and 11 s^–1. *P < .05, **P < .01 compared with wt blood or as indicated. (B) Plasma viscosity (wt, □; tg, ▦) was measured at predefined shear rates ranging from 45 s^–1 to 450 s^–1. (C) SDS-PAGE of plasma and serum of wt and tg mice. Neither plasma viscosity nor plasma or serum protein pattern and concentrations differed significantly between the mouse groups.