A novel approach has been developed to determine the amount of residual water in human erythrocyte at room temperature by electronic particle counter. Nacl solutions of 13 osmolalities were prepared and the equilibrium cell volumes in which were measured one by one.The isotonic volume, V0, was obtained under the isotonic condition. The mean RBC volumes of 5 donors at each osmolality were fitted according to Boyle van’t Hoff relationship, and the osmotically inactive volume, Vb, of erythrocyte was then determined. The results show that Vb50% V0. More importantly, the final cell volume with regard to the solution of the highest concentration found to be kept at about 0.5 V0. The difference between these two volumes is unconspicuous. According to the published data that non-water volume of human erythrocyte is about 28.3% of its isotonic volume, residual water of human erythrocyte can be gained by subtracting V dry from Vf, that is V rw =21.7% V0. Then it was concluded that the residual water of human lays in 2 states, one is bound water, and the other is free water.
A new type electronic particle counter (EPC, MultisizerTM 3, Beckman Coulter Inc., USA) was used to determine the volumes of human red blood cells (RBCs) in NaCl solutions of different osmolalities. The thermodynamics model describing cell response during freezing process was used to simulate the volume change of RBC in 0.9% NaCl solution during equilibrium freezing process. It was assumed that the effect of temperature on cell volume can be neglected compared to that of osmolality, then by using the phase diagram for the binary system sodium chloride/water, the osmolalities of the NaCl solution under different sub-zero temperatures can be obtained (converted from mass concentration), then the calculated values of RBC volumes can be validated by the experiments.
The novel differential scanning calorimetry method for determining trapped water volume of human red blood cell during freezing process has been reexamined. Results show that the final erythrocyte volume is 53% of its isotonic volume after freezing to -40℃. An electronic particle counter (MultisizerTM III, Beckman Coulter Inc., USA) was used to measure cell volume changes in response to hypertonic solution. Using this approach, when extracellular solution was 3186 mOsm, the equilibrium cell volume was found to be 57% of its isotonic value. Both results indicate that 34%—40% of intracellular water is trapped and cannot respond to osmotic difference between intra- and extracellular solution. These findings are consistent with the published data: at least 20%—32% of the isotonic cell water volume is retained within RBCs during freezing. Some applications of the values of trapped water are addressed.
ZHAO Gang1, HE Liqun1, GUO Xiaojie2, LIU Zhong3, LUO Dawei1,3 & GAO Dayong1,3 1. Cryobiomedical Engineering Research Institute, Department of Thermal Science and Energy Engineering, University of Science and Technology of China, Hefei 230027, China
