Effect of 17 beta-estradiol on partition behavior of human erythrocytes in dextran-poly(ethylene glycol) aqueous phases

Preincubation with 1 nM 17 beta-estradiol changes the partition behaviour of human erythrocytes in dextran-poly(ethylene glycol) aqueous phases. Erythrocyte partition decreases reaching a minimum after 5 min of incubation, then slowly increases returning to starting values after 30 min. The effect is specifically induced by the isomer of estradiol, whereas the alpha isomer and other steroid hormones (progesterone, testosterone and 5 alpha-dihydrotestosterone) are uneffective. The effect of the hormone can be suppressed by treatment of erythrocytes with either N-ethyl maleimide, sodium vanadate, or ouabain, or carrying out incubations in potassium-free buffer. These data suggest that the effect of estradiol on phase partition of erythrocytes is mediated by the (Na,K)-ATPase.