[Effect of low temperature exposure on the membrane permeability of erythrocytes reconstructed in media of different ionic strength].

A study was made of the egress of hemoglobin, 14C-saccharose, Na+ and K+ from red blood cells reconstituted in media of varying ionic composition and exposed to rapid freezing and thawing. The reconstitution of red blood cells in a medium containing Na+ (150 mM) and Mg2+ (4 mM) favours their resistance to rapid freezing and thawing that is confirmed by the data on their permeability by hemoglobin, 14C-saccharose and cations. Red blood cells reconstituted in KCl (150 mM) combined with Mg2+ (4 mM) or Ca3+ (50 mcM) are cryolabile. The increased cryoresistance of the reconstituted red blood cells in the presence of Na+ is of nonspecific nature and mostly related to the effect on the inner surface of the plasmatic membrane. Impairment of the permeability of the reconstituted red blood cells correlates with the diminished cellular volume after freezing and thawing.