Role of dehydration in changing the permeability of erythrocyte plasma membranes by freeze-thawing.

The effects of hypertonic solutions and slow freezing to different temperatures in the range of 0 to -80 degrees C on the permeability of plasma membranes of reconstituted erythrocytes were investigated. It has been found that even increased concentrations of NaCl or KCl (1.2 to 4.2 M) do not change appreciably release of K+, [14C]sucrose and haemoglobin (by 8 to 20%), while leakage of markers into the supernatant fluid is essentially completed on freezing to -25 degrees C. If the content of mobile water in the sample of reconstituted erythrocytes is lower than 1 to 2%, the permeability of plasma membranes for [14C]sucrose and haemoglobin changes after freezing to -19 to -22 degrees C. These findings suggest that the existence of water-dependent structural changes in the membranes can be responsible for a primary mechanism of altering the permeability at low temperatures.