Effects of valinomycin, A23187 and repetitive sickling on irreversible sickle cell formation

The formation of irreversibly sickled red cells has been studied by inducing cell shrinkage, ion loss, Ca2+ accumulation and membrane loss either singly or in combination. Valinomycin, A23187+Ca2+ or hypertonic saline caused shrinkage of the cells with retention of the sickled form after reoxygenation. The cells which had retained the sickle shape after treatment with the ionophores and reoxygenation remained sickled after exposure to hypotonic media. These cells were also osmotically insensitive. Retention of the sickled form was not dependent upon membrane loss as induced by repeated sickle-unsickle cycles or by A23187+Ca2+ treatment although repetitive sickling did give rise to shorter, stubbier spicules. Sickled red cells, either the endogenous irreversibly sickled cells or the sickled cells induced by deoxygenation, did not lose membrane by vesicle or spicule loss as normal cells or oxygenated sickle red cells do. Cell water loss without cell membrane loss appears to be an important factor in the irreversible sickling of red cells.