Molecular changes in erythrocyte membranes induced by nitroimidazoles and radiation.
A damage of erythrocyte membranes by gamma-irradiation in the presence of nitroimidazole derivatives was shown by the demonstration of their effect on lipid peroxidation and SDS-PAGE protein pattern (1000 Gy) as well as on electron spin resonance (ESR) spectra of maleimide spin-labels attached to the membrane (for doses < or = 300 Gy). Erythrocyte membranes were labeled with two maleimide labels MAL-6 and MAL-M-3-PROXYL under strictly controlled and reproducible conditions with incubation at physiological temperature of 37 degrees C. The labels were bound to SH groups on the protein surface (weakly immobilized W-sites) as well as to internal SH-groups (strongly immobilized S-sites). The amplitude ratio W/S of the ESR signals was used for a monitoring of an influence of nitroimidazole drugs and gamma-irradiation. The influence appeared, even for the lowest doses, only when nitroimidazole drug was attached to the membrane. It was due to a destruction of spin-label paramagnetic centre both at W and S-sites and was related to the recombination processes during radiolysis connected with nitroimidazoles. It indicated a radiosensitivity of the nitroimidazoles. However, the persistent degradation of the membranes by the oxidative stress appeared above the threshold dose of 300 Gy determined from transformation of the W-sites into S-sites in ESR spectra. For the higher dose (1000 Gy) a fragmentation of the band 3 proteins was clearly seen as well as a partial damage of higher molecular-weight proteins with a simultaneous formation of much higher molecular-weight polymers.
Rybczyńska
M
M
Department of Clinical Chemistry, Karol Marcinkowski Medical Academy, Poznań, Poland.
Hoffmann
S K
SK
Goslar
J
J
D003497:Cyclic N-Oxides; D003720:Densitometry; D004578:Electron Spin Resonance Spectroscopy; D015180:Electrophoresis, Gel, Two-Dimensional; D004910:Erythrocyte Membrane / Q000187:drug effects / Q000528:radiation effects*; D005720:Gamma Rays; D006801:Humans; D066298:In Vitro Techniques; D015227:Lipid Peroxidation / Q000187:drug effects; D009593:Nitroimidazoles / Q000009:adverse effects* / Q000494:pharmacology; D013113:Spin Labels
D003497:Cyclic N-Oxides; D009593:Nitroimidazoles; D013113:Spin Labels; C017480:4-maleimido-2,2,6,6-tetramethylpiperidinooxyl; C024516:N-(1-oxyl-2,2,5,5-tetramethyl-3-pyrrolidinyl)maleimide