[Changes in erythrocyte membrane-cytoskeleton complex, induced by dimethyl sulfoxide, polyethylene glycol, and low temperature]

The effect of the cryoprotectants DMSO and PEG-1500 as well as freezing-thawing on the proteins of the canine erythrocyte membrane-cytoskeleton complex has been studied using the cross-linking reagent diamide. It was shown that the intensity of distortions in the protein network structure correlated to an increase in SH-group accessibility for the oxidation by this compound and accordingly, the enhancement of the formation of high-molecular-weight protein aggregates. The maximum level of diamide-induced aggregability was revealed upon freezing of erythrocytes in liquid nitrogen without the cryoprotectant. The electrophoretical analysis of the ghost proteins of erythrocytes incubated with cryoprotectants showed a significant increase in the aggregation level only in cells present in the polymer solution. After the freezing-thawing cycle, the diamide-induced protein aggregability in erythrocytes cryopreserved with PEG-1500 strongly increased, while if DMSO was used for cell protection, the level of aggregates was much less pronounced than in the control. One can suppose that the exocellular cryoprotectant PEG-1500, as distinct from the endocellular cryoprotectant DMSO, is unable to provide the preservation of the structure of the membrane-cytoskeleton protein complex at the acceptable level necessary for the maintenance of cell integrity after the return to the physiological conditions.