Heats of activation for the exosmotic flow of water across the membrane of leucocytes and leukemic cells

The permeability of the membranes of different types of leucocytes from several mammalian species to the exosmotic flow of water has been measured at different temperatures. Heats of activation for the process have been calculated. Results indicate that the leucocyte has an unusually high heat of activation for the osmotic movement of water across its outer membrane, ranging between 13 to 18 kcal/mole. Unconstrained water movement usually has values between 3 to 5 kcal/mole. This property characterizes all leucocytes examined to date, regardless of species or type. It is apparent that water is intimately associated with the outer boundary of the cell and that this association is quite sensitive to the structural changes which must occur in response to changes in temperature.