Differentiation-associated changes of cation-transport activities in myeloid leukemic cell lines

Induction of differentiation in HL-60 and U-937 leukemic cell lines, resulted in 1.5-10-fold increase in ⁴⁵Ca²⁺ uptake. The increased ⁴⁵Ca²⁺ uptake in the differentiating cells was inhibited by verapamil, cromolyn and amiloride. Elevation in Ca²⁺ uptake in differentiating cells was also demonstrated using the fluorescent probe, fura-2 acetoxymethyl ester. The increased ⁴⁵Ca²⁺ uptake was accompanied by a decrease in ouabain-insensitive and -sensitive ⁸⁶Rb⁺ uptake. Furthermore, correlation between the changes in these activities was observed. Modulation of extracellular pH affected differentiation: higher pH increased the extent of differentiation.