ABSTRACT
This chapter discusses the behavior of water and solutes in cells and the basis for their equilibrium and transport across cell membranes, and the general principles, processes, and phenomena involved in the control of animal cell volume under both steady-state and anisotonic conditions. Today, volume regulation research has branched out to involve many disciplines, from ion transport and electrophysiological studies to cellular signaling and molecular genetics. The situation becomes more complex when one tries to account for the distribution of all charged solutes and solvent water in a living cell. In attempts to model this distribution, the classical Donnan equilibrium formalism is often used. The membrane protein that forms water channels in red blood cells and some kidney cells was first identified as a contaminant of about 28 kDa molecular weight in preparations of an Rh antigen-bearing polypeptide from red blood cells.
