Supersaturation in sickle cell hemoglobin solutions.

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Abstract
The kinetic inhibition of the gelation of Hb S is compared to the change in Hb S solubility, when the solubility is altered by CO, pH or urea. By means of a new technique, the delay time and the extent of gelation are measured on the same sample. The delay time, td, is proportional to a high power (30-40) of the Hb S solubility. Together with the previously reported concentration dependence, this result demonstrates that the rate is proportional to a high power of the supersaturation, S, defined as the ratio of the total Hb S concentration to the equilibrium solubility. The results obey the supersaturation equation td-1 = .gamma.Sn, where .gamma. is an empirical constant (about 10-7 s-1) and n is about 35. The supersaturation equation can successfully account for observations on the kinetics of cell sickling and is used to estimate the increase in the delay time for sickling necessary to produce significant clinical benefit to patients with sickle cell disease.