Damage to Human Erythrocytes by Radiation-generated HO• Radicals: Molecular Changes in Erythrocyte Membranes

Abstract

The effectiveness of radiation-generated HO* radicals in initiating erythrocyte hemolysis in the presence of oxygen and under anaerobic conditions and prehemolytic structural changes in the plasma-erythrocyte membrane were studied. Under anaerobic conditions the efficacy of HO* radicals in induction of hemolysis was 16-fold lower than under air. In both conditions, hemolysis was the final consequence of changes of the erythrocyte membrane. Preceding hemolysis, the dominating process under anaerobic conditions was the aggregation of membrane proteins. The aggregates were principally formed by -S-S- bridges. A decrease in spectrin and protein of band 3 content suggests their participation in the formation of the aggregates. These processes were accompanied by changes in protein conformation determined by means of 4-maleimido-2,2,6,6-tetramethylpiperidine-N-oxyl (MSL) spin label attached to membrane proteins. Under anaerobic conditions, in the range of prehemolytical doses, the reaction of HO* with lipids caused a slight (10-16%) increase in fluidity of the lipid bilayer in its hydrophobic region with a lack of lipid peroxidation. However, in the presence of oxygen, hemolysis was preceded by intense lipid peroxidation and by profound changes in the conformation of membrane proteins. At the radiation dose that normally initiates hemolysis a slight aggregation of proteins was observed. Changes were not observed in particular protein fractions. It can be suggested the cross-linking induced by HO* radicals under anaerobic conditions and a lack of lipid peroxidation are the cause of a decrease in erythrocyte sensitivity to hemolysis. Contrary, under aerobic conditions, molecular oxygen suppresses cross-linking, catalysing further steps of protein and lipid oxidation, which accelerate hemolysis.

The heritability of hemolysis in stored human red blood cells

“…23 Lipid peroxidation is known to be a prelude to hemolysis. 24 Therefore, the mechanisms we hypothesize would be lipid specific and not generalizable to all unsaturated lipids.…”

Effects of low doses of gamma rays on the stability of normal and diabetic erythrocytes.

“…It is well proven that the mechanisms of radiation-induced biomolecular damage involve the generation of free radicals followed by their attack on proteins, lipids and carbohydrates (Hannig et al, 2000). Gamma irradiation can cause a variety of membrane changes which occur also during the aging processes, described above, for example lipid peroxidation, hydrolysis of phospholipid head groups, lipid-lipid or lipid-protein crosslinking, disulfide bridge formation, and amino acid residue damage in membrane proteins (Szweda-Lewandowska et al, 1989;Lee et al, 1994;Petkau, 1971;Graeub, 1994;Szweda-Lewandowska et al, 2003;Komorowska et al, 2007;. Therefore due to the alteration of many enzymatic pathways in diabetic RBCs resulting in a strong modification of the lipid and protein membrane components one could predict that the ionizing γ-radiation applied in our studies would influence the stability of the healthy and diabetic cells in a different way.…”

“…The dose rate of 0.04 mGy /min is only 8000 times higher than that from the background radiation which is about 5 nGy/min. Usually the dose rates investigated exceed this value by tens of orders of magnitude (Gwoździński, 1991;Iyer et al, 2002;Szweda-Lewandowska et al, 2003;Kokosz et al, 2006). γ-Radiation doses of 500-1000 Gy induced alterations of the RBC membrane at the level of lipid bilayer and skeleton proteins influencing in this way the membrane permeability and cell stability as well as hemoglobin states inside the cells (Shapiro et al, 1968;Gwoździński, 1991;Iyer et al, 2002).…”

Fullerenols as a New Therapeutic Approach in Nanomedicine

“…As a result of the radiolysis of water, a number of reactive species are formed, most of which are radicals capable of reacting with biological molecules and influencing their functions. The most reactive oxidant is the hydroxyl radical, having a very high redox potential which allows it to react with virtually every molecule found in the cell [26, 27]. …”