4-maleimido-2-2-6-6-tetramethylpiperidinooxyl and Hemolysis

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.

Topics: Cell Membrane; Cyclic N-Oxides; Densitometry; DNA Damage; Dose-Response Relationship, Radiation; Electrophoresis, Polyacrylamide Gel; Erythrocyte Membrane; Erythrocytes; Hemolysis; Humans; Hydroxyl Radical; Lipid Bilayers; Lipid Metabolism; Lipid Peroxidation; Lipids; Oxygen; Protein Conformation; Reactive Oxygen Species; Spin Labels

Molecular events on the human erythrocyte membrane subsequent to influence virus binding were investigated by electron spin resonance (ESR) measurements after spin labeling of the cell membrane at different positions. Virus binding affected the glycocalyx structure as well as the physical state of the cytoskeleton at the inner leaflet, but not the lipid phase. A lateral reorganization of spin-labeled glycophorin was not indicated after virus attachment.

Topics: Absorption; Attachment Sites, Microbiological; Cell Fusion; Cyclic N-Oxides; Cytoskeleton; Electron Spin Resonance Spectroscopy; Erythrocyte Membrane; Glycoproteins; Hemolysis; Humans; Hydrogen-Ion Concentration; Membrane Fluidity; Microscopy, Electron; Orthomyxoviridae; Polysaccharides; Spin Labels; Temperature

Spin-label studies of the effects of hyperthermia on the erythrocyte membrane revealed a decrease in the fluidity of lipids and changes in the state of membrane proteins. The rate of haemolysis in iso-osmotic glycerol solution was increased. Changes of most of the parameters studied when plotted in Arrhenius coordinates revealed a discontinuity (critical hyperthermic transition in the membrane) between 46 and 50 degrees C. Studies of the combined action of ionizing radiation (100 Gy) and hyperthermia (43 degrees C) showed the same direction of changes for (Na-K-Mg)-ATPase activity and spectra of membrane-bound maleimide spin label for both agents, but the additivity of changes depended on the parameter studied.

Topics: Animals; Cattle; Cobalt Radioisotopes; Cyclic N-Oxides; Electron Spin Resonance Spectroscopy; Erythrocyte Membrane; Erythrocytes; Gamma Rays; Hemolysis; Hot Temperature; Sodium-Potassium-Exchanging ATPase; Spin Labels