ABSTRACT
From a historical perspective, it seems useful to remember that, the transport of water by epithelia was not connected to the notion of solute-solvent coupling. Different papers appeared in which the tonicity of fluids transported by different epithelia had been calculated without assuming that transport was restricted to a small segment of the channel. These were those of B. S. Hill, J. J. Lim, and Jorge Fischbarg, and H. Sackin and E. L. Boulpaep. One might ask what precisely are the values for the cell membrane (Pos) osmotic permeabilities and the gradients one needs to account for isotonic transport. The chapter focuses on the route of water movement across cell membranes. This route emerges as crucial for the theory of water transport by cells and tissues. Another reasonable candidate for lodging the water channel is none other than the ubiquitous glucose transporter protein. The chapter concludes that water may traverse a glucose transporter channel.
