Computer-simulated urea reflection coefficients in human red cells.

Relative volume curves for human red cells were generated with a computer program to simulate the experimental results obtained by rapidly mixing red cells and urea. Known values for the permeability variables were used in the Kedem and Katchalsky (Biochim. Biophys. Acta (1958) 27, 229-246) solute and solvent flux equations. The different values used for the reflection coefficient, o, were 0.62, 0.75 and 1.0. The theoretical computer curves with o = 0.75 compared closely with the experimental stopped-flow curves.