The effects of alkylureas and nitrogen mustards on the kinetics of red cell sickling.

A continuous flow apparatus was designed for the study of the kinetics of red cell sickling. Cells were mixed with buffered sodium dithionite in one mixing chamber and after transversing variable length pathways were fixed with isotonic formalin in a second mixing chamber. Hb SC-containing red cells sickle at a slower rate than Hb SS red cells, exhibiting a clearly detectable log period. The effect of butylurea on sickling of SS or SC cells is due to the inhibition of the extent of sickling as well as the extension of the time required for sickling. This effect is concentration dependent, which suggests that at least some of the pregelling events in a solution of deoxy Hb S are based on hydrophobic interactions. Nitrogen mustards, on the other hand, inhibit the extent of red cell sickling without modifying the rate of sickling at the concentrations used.