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.

The Impact of Ca2+ on Intracellular Distribution of Hemoglobin in Human Erythrocytes

“…Ca 2+ activation of the calmodulin 4.1R has been found to reduce the latter’s affinity for its cytoskeletal targets, thus affecting the spectrin/actin network and cell shape [ 42 ]. Moreover, the possible involvement of intracellular rearrangement of Na + and K + in Hb redistribution due to functional alteration of the Na + /K + pump should also be considered [ 43 ]. The specific interactions of Hb and Ca 2+ with anionic phosphatidylserine [ 44 , 45 ] may indicate that the more positive HbA2 variant shares binding sites for Ca 2+ in stabilizing the membrane’s phospholipid distribution.…”

The microorganism effect on the erythrocyte morphofunctional parameters and the hemoglobin oxygen- binding capacity

“…3). The magnitude of the optical path difference makes it possible to characterize the cell thickness and the redistribution of hemoglobin molecules in red blood cells [3,9].…”

“…It is known that the oxygen transport function of red blood cells depends not only on hemodynamics and hemoglobin-oxygen a nity, but also on the hemoglobin molecule conformation. One of the diagnostic methods for the hemoglobin conformation in red blood cells is Raman scattering spectroscopy, which allows the hemoglobin content and conformation to be assessed without preliminary sample preparation in vitro [3].…”

“…According to the literature data, the role of red blood cell ionic homeostasis in changes in cell morphology and volume is known [3]. The microorganism effect on morphofunctional changes in red blood cells and conformational rearrangements of the hemoglobin molecule have been poorly investigated.…”

“…It is known that changes in the RBC morphology and volume lead to changes in the hemoglobin ability to bind or shed ligands (О 2 and NO x ) [3]. It is also known that the oxygen transport function of red blood cells depends on both hemodynamics and the hemoglobin conformation, but the microorganism effect on the hemoglobin conformation has been insu ciently explored.…”