Osmotic Properties of Living Cells

Abstract

Publisher Summary This chapter describes the theory of osmotic pressure, osmotic properties of protein solutions, the relationship between volume and osmotic pressure at equilibrium in living cells, and kinetics of osmotic volume changes in living cells. The chapter also investigates isolated cells maintained under normal or nearly normal physiological conditions. There are a number of different methods of measuring and expressing the permeability of the cell to water which are based on various assumptions about the cell; however the accuracy of these assumptions largely determines the significance of the different permeability values obtained. Water movement is probably most strongly impeded at the cell membrane, but the internal protoplasm of the cell also offers significant resistance. Consequently all permeability coefficients calculated by conventional methods are probably too low. The chapter suggests that further studies of the osmotic permeability of isolated cells must include data of the cell dimensions for the calculation of the surface–volume ratio and sufficiently full time–volume data for the calculation of the diffusion coefficient of water in the protoplasm.