How erythrocyte volume is regulated, or what mathematical models can and cannot do for biology

Modern concepts of the red blood cell (RBC) volume regulation are considered. It is shown that the system of ion pumps and channels in the cell membrane ensures the physiological value of volume with a precision of about 10% even at 5- to 7-fold variations of passive membrane permeability for ions. Particular attention is paid to mathematical models for evaluation of the role of different molecular mechanisms in the RBC volume control. It is shown that many questions, for example, ‘why the Na + ,K + -ATPase pumps the ions in opposite directions’ or ‘what is the physiological role of Ca 2+ -activated K + -channels’, cannot be answered without adequate mathematical models of such complex control systems as cell volume control.