Two-step rapid freezing method: estimation of membrane hydraulic permeability in erythrocytes at temperature exposure stage.

The processes, occurring at the stage of temperature exposure under two-step freezing of human and hibernating ground squirrel erythrocytes were studied by electron-microscopic method of freeze-fracturing. For human erythrocytes the time of intracellular crystal dissolution in human erythrocytes made 30 min and this value was shown to be slightly depending on temperature within -20 to -35 degree C range. Erythrocyte membrane permeability for water within negative temperature range has been estimated. It was noted that the value of water membrane permeability coefficient obtained theoretically, taking into account experimental values of time of dissolution for intracellular ice crystals and cell dehydration, is quite well consistent with the reported data and equals to about 0.5 x E-13 (cubic m)/N/sec for human erythrocytes and E-13 (cubic m)/N/sec for hibernating ground squirrel cells. Under two-step freezing a temperature arrest results in a qualitative change of water exchange process between cell and its environment, and the exposure duration may serve as the measure for cell dehydration. According to the data of NMR "paramagnetic doping" and freeze-fracturing the erythrocyte membrane of hibernating ground squirrels is more permeable for water than human one.