IN THE ERYTHROCYTE HEMOGLOBIN CONFORMATION AND DISTRIBUTION DURING RBC VOLUME CHANGES

Abstract

The intracellular space of red blood cells (RBC) includes 40% hemoglobin (Hb) molecules and 60% being water molecules. When the intracellular volume changes, which is possible when erythrocyte cells pass through the blood stream, the possibility of redistribution of intracellular components of the cell due to its volume changes is assumed. By methods of optical spectroscopy (non-invasive methods of infrared spectroscopy, Raman-spectroscopy, laser interference microscopy) changes of morphology, conformation and redistribution of Hb have been revealed in the human erythrocyte due to an increase in the ratio of [Na+]in and [K+]in when Na+/K+-ATPase is blocked in the cell. The decrease of activity of Na+/K+-ATPase by a ouabaine (3 mM) has been found to lead not only to an increase in [Na+]in cell but also to an increase in positive charge on the cytoplasmic surface of the RBC membrane. In these conditions, changes in the conformation of both the heme and globine parts of the cytoplasmic Hb have been identified. It has been shown that cell depolarization, together with cell volume change, leads to a decrease in packing density of Hb molecule, which may be related to sorption of intracellular Na+ (or Ca2+) c Hb, as well as increasing the amount of water molecules in the cell and redistributin Hb in the cell. These processes can lead to a change in the conformation of Hb, as well as to a redistribution and alteration of the conformation of the cytoplasmic Hb.