Viscosity and filtrability measurements of sickle-cell suspensions in the development of anti-sickling drugs.

We have developed two rheological methods for use in the study of the effect of anti-sickling drugs on in vitro sickling: (a) An automated instrument which measures the relationship between the oxygen partial pressure and blood viscosity, and (b) an instrument to measure the relationship between filtrability (through a 3 mu-pore Nuclepore filter) and the oxygen partial pressure. With these instruments, we found that both viscosity and filtration pressure of a sickle-cell suspension increased even at oxygen saturation values above 90%, levels at which morphological changes of sickle cells are not yet pronounced. The effect of anti-sickling drugs was demonstrated by a decrease of the filtration pressure at low oxygen saturation.