The effect of variation of transport Na/K- or Na- ATPase and hexokinase (HK) activity on erythrocyte volume stabilization.

Panels (A) and (B) show the dependence of the relative erythrocyte cell volume on the non-selective cell membrane permeability for cations (g) at different values of transport Na/K-ATPase activity (A) or HK activity (B) in the base version of the model (model version 1). The numbers on the curves indicate relative activity of the corresponding enzyme. Panel (C) shows the dependence of the physiological erythrocyte volume on the activity of the transport Na/K-ATPase (model version 1, curve 1) or transport Na-ATPase (model versions 2 and 3). Panel (D) shows the dependence of the physiological erythrocyte volume on HK activity in the models with Na/K-ATPase (curve 1) or with Na-ATPase (curves 2 and 3). The red stripes mark the area of maximal erythrocyte volume (V/V0 = 1.7–1.8) at which the cell takes a spherical shape. For curve 2 (panel A) and for curve 0.5 (panel B) at high g values as well as for curve 3 (panel D) at low HK activity values the steady state in glycolysis disappears.