OSMOTIC STATES OF THE RED BLOOD-CELL

1. Permeative properties of the red blood cell membrane are utilized for an introduction of three osmotic states of the model cell with respect to equilibration of certain cell solution constituents across the membrane equilibration of water (W state), equilibration of water and chloride (C state), and equilibration of water, chloride and cations (D state). 2. The model cell introduced consists of the semipermeable membrane which separates the buffered external solution composed of water, univalent electrolyte, and sucrose from the internal hemoglobin and electrolyte solution. Three sets of equations each describing corresponding osmotic state are given. Certain physicochemical properties of the hemoglobin solution are taken into account. The inner pH is assumed to be established according to the chloride distribution across the membrane. 3. The volume and electric potential difference of the model cell are calculated for each osmotic state at different ratios of sucrose and electrolyte concentration of external solutions. Results are used for an analysis of general osmotic properties and lysis of red cells. 4. It is shown how cells are expected to behave if exposed to conditions with different osmotic pressure, composition of external solutions, or temperature. The importance of temperature effect and rate of performing osmotic experiments on the existence of the W state is pointed out. 5. Different experimental procedures which cause an increase in the membrane cation premeability are discussed in terms of the transition from the C to D state. It is indicated that after the membrane modification in the cases discussed osmotic accomodation of cells is governed by the net-chloride diffusion. © 1979.