Kofanova O. Modification of Ca2+-ATPase functional activity and membrane-cytoskeleton complex of erythrocytes under glycerol and cryopreservation effects

Dissertational work is devoted to studying the changes of Ca2+-ATPase functional activity and the level of free cytosolic Ca2+ in human erythrocytes under glycerol and low temperatures effects, and also the estimation of Ca2+-dependent reorganizations of phosphotidylserine transmembrane distributions in the lipid bilyer as well as protein-proteins interactions in the membrane-cytoskeleton complex, which are induced by cryoprotectant and cryopreservation. The modification of Ca2+-pump activity in saponin-permeabilyzied erythrocytes was established to have a biphase character under increasing glycerol concentrations. The analysis of endogeneous modulator role with using the inhibitor of calmodulin-regulated reactions R24571 has shown that the activation of Ca2+-pump at 10% glycerol presence was realized only with the calmodulin participation. It was also noted that its enzymatic activity in erythrocytes cryopreserved under glycerol protection depressed after freezing and raised after their deglycerolization. It was shown that the level of free cytosolic Ca2+ in erythrocytes under glycerol effects was increased, but was maintained at a lower level in comparison with erythrocytes where the Ca2+-pump activity was inhibited by vanadate. In cryopreserved cells after deglycerolization the Ca2+ level was even more elevated in comparison with conditions of their incubation in glycerol presence. Influence of glycerol and low temperatures on the change of asymmetric phosphotidylserine distribution in erythrocyte plasma membrane was slightly pronounced during rather short period of time after these impacts. Ca2+-induced reorganizations in membrane-cytoskeleton complex were demonstrated under glycerol and cryopreservation effects.