Variable shear-rate viscometry of native dog blood;effect of heparin injection 1

A variable shear rate, non-pulsatile capillary viscometer for measurements of blood circulating in chronic exteriorized A–V shunts in dogs has been constructed. Nominal values of reduced average velocity (Ū) obtainable with this instrument range from 28 to 560 sec⁻¹ in 200μ i.d. tubes. Experimental data are reported for measurements obtained from both native and heparinized blood. Conclusions are: (1) acute heparinization has no effect on the rheological properties of dog blood and (2) dog blood can be described as a pseudoplastic, non-Newtonian suspension, with apparent viscosity decreasing as either shear rate increases or hematocrit decreases. Both conclusions are limited to the range of hematocrit (20–50 per cent) and Ū studied.