127 Measuring of Sf21 cell membrane biophysical parameters using a new nondilute solute transport equation

Abstract

In cryobiology, Kedem-Katchalsky model (KK) and two-parameter model (2P) has been used to predict cell volume changes. However, the KK model might lead to conceptual errors when used for cell membranes and the 2P model is based on ideal and dilute solution. Recently, Heidi Y. Elmoazzen et al. (Heidi Y. Elmoazzen, Janet A. W. Elliott, and Locksley E. McGann, “Osmotic Transport across Cell Membranes in Nondilute Solutions: A New Nondilute Solute Transport Equation,” Biophysical Journal, vol. 96, pp. 2559–571, 2009) had proposed a new nondilute solute transport equation which could fit or predict cell osmotic volume changes more appropriate. The purpose of the article is to verify the validity of the new equation. We used SF21 cell volume changes in different concentrations of Glycerol and different temperatures to fit the new model to water permeability coefficient ( L ) and solute permeability coefficient ( P ) of cell membrane. The experiment was carried out by using microperfusion system designed by our lab. What’s more, the extracellular concentration of CPA was simulated by using a universal self-adaptive time-varying function, which is derived by Gang Zhao (Gang Zhao, “A Universal Self-Adaptive Time-Varying Function for Extracellular Concentration during Osmotic Shift for Curve-Fitting Permeability Coefficients of Cell Membrane,” Cryoletters, vol. 31, pp. 279–90, 2010). Mean (means ± SD) L values in the presence of 2.0 M Glycerol at 25, 20, 15, and 10 °C were determined to be 0.68 ± 0.29, 0.78 ± 0.33, 0.77 ± 0.20, and 0.67 ± 0.16 10-28mol2/ (minatm μ m5). The P values were 4.6 ± 0.1.69, 1.11 ± 0.99, 3.84 ± 0.65, and 2.96 ± 2.81 10–32 ml 2 / (minatm μ m 5 ). L values in the presence of 1.5 M Glycerol at 25, 20, 15, and 10 °C were determined to be 0.97 ± 0.61, 1.27 ± 0.64, 0.818 ± 0.29, and 0.533 ± 0.17 10–28mol 2 / (minatm μ m 5 ). The P values were 4.18 ± 2.51, 3.00 ± 1.62, 1.14 ± 0.58, and 2.3 ± 1.53 10–32 mol 2 / (minatm μ m 5 ). L values in the presence of 1.0 M Glycerol at 25, 20, 15, and 10 °C were determined to be 1.78 ± 0.65, 1.24 ± 0.66, 1.02 ± 0.26, and 1.15 ± 0.39 10–28 mol 2 / (minatm μ m 5 ). The P values were 2.67 ± 0.94, 2.70 ± 1.53, 1.45 ± 0.96, and 0.79 ± 0.40 10–32 mol 2 / (minatm μ m 5 ). From fitting lines of the experiment data, we could find out the new nondilute equation is very similar to 2 P model, which demonstrates, in our opinion, the new nondilute equation can be used to fit and predict cell volume changes. Therefore, more experiments should be done to prove which one might lead to a better result. Source of funding: This work was supported by the National Natural Science Foundation of China (Nos. 51076149, 51276179) Conflict of interest: None declared. zhaog@ustc.edu.cn