Characteristics of the radiation-induced changes in the content of sterols and squalene in the lymphoid system tissues and erythrocyte membranes of rats

Ionizing radiation causes considerable changes in the content of sterols and squalene in the lymphoid system tissues and erythrocyte membranes which is in accordance with the concept of high radiosensitivity of haemopoietic tissue. The processes of cholesterol conversion to its oxy-derivatives are increased under the effect of radiation. The content of some lipid components in the lymphoid system tissues and erythrocyte membranes is changed depending on the dose and time after irradiation. There is a relationship between the changes in the sterol composition and in the properties of erythrocyte membranes.     

Influence of MLS laser radiation on erythrocyte membrane fluidity and secondary structure of human serum albumin

The biostimulating activity of low level laser radiation of various wavelengths and energy doses is widely documented in the literature, but the mechanisms of the intracellular reactions involved are not precisely known. The aim of this paper is to evaluate the influence of low level laser radiation from an multiwave locked system (MLS) of two wavelengths (wavelength = 808 nm in continuous emission and 905 nm in pulsed emission) on the human erythrocyte membrane and on the secondary structure of human serum albumin (HSA). Human erythrocytes membranes and HSA were irradiated with laser light of low intensity with surface energy density ranging from 0.46 to 4.9 J cm^?2 and surface energy power density 195 mW cm^?2 (1,000 Hz) and 230 mW cm^?2 (2,000 Hz). Structural and functional changes in the erythrocyte membrane were characterized by its fluidity, while changes in the protein were monitored by its secondary structure. Dose-dependent changes in erythrocyte membrane fluidity were induced by near-infrared laser radiation. Slight changes in the secondary structure of HSA were also noted. MLS laser radiation influences the structure and function of the human erythrocyte membrane resulting in a change in fluidity.     

Radiation-induced lipid peroxidation and the fluidity of erythrocyte membrane lipids

The effect of radiation-induced peroxidation on the fluidity of the phospholipids of the erythrocyte membrane was studied using both erythrocyte ghosts and liposomes formed from the polar lipids of erythrocytes. In liposomes, the oxidation of the phospholipids increased with radiation dose, but there was no change in the fluidity of the lipids as measured by spin-label motion. Under the same conditions of irradiation, no oxidation of phospholipid was detected in erythrocyte ghosts, although changes occurred in the motion of spin labels intercalated with the membrane. These changes were attributed to radiation-induced alterations in the membrane proteins. It is concluded that alterations in motion of spin labels, observed with intact membranes after irradiation, are most likely the result of changes in the structure of membrane proteins rather than the lipids.     

The effect of ionizing radiation on tryptophan fluorescence of thymocyte and erythrocyte plasma membranes

The effect of ionizing radiation on tryptophan fluorescence of thymocyte and erythrocyte plasma membrane preparations was studied. The intensity of tryptophan fluorescence decreased after applying radiation doses up to 15 Gy. The radiosensitivity of thymocyte membranes appeared to be higher than that of the erythrocyte ghosts. Tryptophan radiolysis did not significantly contribute to the effects of radiation. The fraction of tryptophan residues accessible for quenching by I- decreased from 0.87 in the untreated membranes to 0.63 and 0.49 in membranes after doses of 10 and 250 Gy, respectively. The effective quenching constant and the tryptophan fluorescence polarization increased after irradiation. The mechanisms producing these radiation-induced changes are discussed.     

The effect of ionizing radiation on the blood plasma and erythrocytes and on the wall of the abdominal aorta of rats

On days 7 and 15 after gamma-irradiation (4 Gy) changes were noted in the temperature dependence of the erythrocyte suspension viscosity coefficient, in the electrolyte composition of the abdominal aorta, plasma, and erythrocytes, in Na, K- and Mg-ATPase activity, and in the intensity of fluorescence of 1.8 ANS of erythrocyte ghost of albino rats. The changes were a function of the stage of radiation sickness and were more pronounced on the 15th day following irradiation.     

Effect of pulse electromagnetic radiation on erythrocyte ghosts

The pulse microwave radiation has been shown to increase the fluorescence intensity of 2-toluidinonaphthanene-6-sulfonate (2,6-TNS) and 1-anilinonaphthalene-8-sulfonate (1,8-ANS) built-in membranes of erythrocyte ghosts. In experiments with 2,6-TNS a frequency dependence of the effect of microwave radiation with maximum within the frequency range of 55-65 Hz has been found. It is suggested that the changes registered with fluorescent probes are induced by mechanical oscillations generated by the pulse microwave radiation.     

Changes of hexose monophosphate pathway and methemoglobin reductase enzyme activity after radiation in guinea pigs

HMP pathway activity changes occurring after exposure to ionizing radiation (LD50 dose) have been investigated. The study was carried out on 18 experimental guinea pigs subjected to 5 successive exposures of 150 rads 3 or 4 days apart. The control animals were sham radiated but were otherwise treated identically as those of the experimental groups. Blood samples were taken by cardiac puncture before radiation and 30 min after each exposure of 150 rads. The red cells were re-suspended in their own plasma and HMP pathway activity was measured in the suspension. The pathway activity showed a consistent but minor reduction in the experimental group, which became statistically significant after the total dose of 750 rads (P less than 0.020). In a separate study the changes induced by ionizing radiation in the erythrocyte enzyme NADH-methemoglobin reductase were measured using the same experimental protocol. The enzyme activity in the red cells of the experimental group varied between 34.90 +/- 2.17 to 161.95 +/- 5.34 I.U./ml erythrocyte pack. Its activity declined toward the initial value after reaching the peak by the 12th day of ionizing radiation with 600 rads (P less than 0.001).     

Erythrocyte elastic and mechanical properties and mechanism of their change during irradiation

A decrease in erythrocyte deformation, which was maximum at the height of radiation sickness, was registered as early as 1-3 days following 6 Gy irradiation of rats. The aggregation of erythrocytes increased during the latent period of radiation sickness then sharply decreased. The role of the observed changes in radiation sickness then pathogenesis is discussed. It is established that they are associated with the altered fatty acid composition of the lipid phase of erythrocytic membranes, on the one hand, and with the disturbances in its ionic permeability, on the other.     

Radiation-induced changes in the structure of erythrocyte membrane proteins

Structural changes in proteins of erythrocyte membranes induced by gamma-radiation at doses of 10-10(3) Gy were studied using the method of tryptophan fluorescence quenching by acrylamide. It was found that the exposure to ionizing radiation leads to a decrease in intramolecular dynamics of membrane proteins.     

Electromagnetic fields of millimeter range: effect on the structure and functional properties of erythrocyte membranes

The effect of coherent and non-coherent electromagnetic fields of millimetre range on biophysical and biochemical indices of blood erythrocytes and plasma of the animals totally exposed to radiation at various periods of observation (day 1, 5, 10) was studied. The following structure-functional shifts were revealed: deviations in the content of separate phospholipid fractions of erythrocyte membranes, the changes of lipid peroxidation products in erythrocyte membranes and blood plasma of the irradiated animals, statistically significant increase of K ions out-flow from the erythrocytes, as well as the alteration of the value of membrane potential of erythrocytes.     

Effect of radiation on some haematological parameters and its modification by vitamin E in chicks.

White leghorn male chicks of 1 and 7 day age groups were studied for acute (2.25 Gy) gamma radiation (with or without vit. E pretreatment) induced haematological changes in the peripheral blood at days 1, 3, 5, 7, 14 and 28 postirradiation. A continuous decrease in the erythrocyte numbers was observed in the animals irradiated without vit. E treatment. The changes in haematocrit, haemoglobin, MCV, MCH and MCHC values were in line with the erythrocytic changes reflecting radiation induced damage to the erythroid elements. Animals pretreated with vit. E show lesser depression in the erythrocytic component at all the stages indicating its radio-protective influence. The significant increase in the immature RBC's in the peripheral blood in vit. E treated animals after irradiation, implies enhanced erythropoiesis.     

Effects of acute low doses of Gamma-radiation on erythrocytes membrane

It is believed that any dose of ionizing radiation may damage cells and that the mutated cells could develop into cancer cells. Additionally, results of research performed over the past century on the effects of low doses of ionizing radiation on biological organisms show beneficial health effects, called hormesis. Much less is known about the cellular response to low doses of ionizing radiation, such as those typical for medical diagnostic procedures, normal occupational exposures or cosmic-ray exposures at flight altitudes. Extrapolating from the effects observed at higher doses to predict changes in cells after low-dose exposure is problematic. We examined the biological effects of low doses (0.01–0.3 Gy) of γ-radiation on the membrane characteristics of erythrocytes of albino rats and carried out osmotic fragility tests and Fourier transform infrared spectroscopy (FTIR). Our results indicate that the lowest three doses in the investigated radiation range, i.e., 0.01, 0.025 and 0.05 Gy, resulted in positive effects on the erythrocyte membranes, while a dose of 0.1 Gy appeared to represent the limiting threshold dose of those positive effects. Doses higher than 0.1 Gy were associated with the denaturation of erythrocyte proteins.     

Enzymes protecting the erythrocyte membrane during the combined exposure to an antioxidant complex and acute irradiation]

The data are presented concerning the effect of ionizing radiation on the hemolytic process and the influence of an antioxidant vitamin complex on the pentosephosphate metabolism and glutathione reductase activity after gamma-irradiation. The antioxidant vitamin complex has been shown to produce a favourable effect on the erythrocyte membrane stability in correcting the radiation-induced changes.     

Effects of microwave radiation (340 and 900 MHz) on different structural levels of erythrocyte membranes

By use of fluorescence probes 1-anilinonaphthalene-8-sulfonic acid, 2-toluidinylnaphthalene-6-sulfonate, pyrene, perylene and chemical label phosphatidylethanolamine 2,4,6-trinitrobenzele sulfonic acid, the effect of microwave radiation on the erythrocyte membrane was studied. The studies with the fluorescence probes were carried out on erythrocyte ghosts and with 2,4,6-trinitrobenzene sulfonic acid on whole erythrocytes. The fluorescence was measured during irradiation of the membranes with 340-MHz microwaves at an SAR of 100 W/kg. Trinitrophenylation of phosphatidylethanolamine from whole erythrocytes was performed simultaneously with microwave irradiation at 900 MHz (10 mW/cm2). It was shown that the microwave field decreased lipid viscosity, altered the structural state of lipid-protein contact regions, and decreased the protein shielding of lipids. These changes corresponded to those produced by thermal action of microwaves.     

Effect of ultra-low dose of ionizing radiation on the surface potential of erythrocytes

Effect of ionizing radiation in ultralow dose (5 microGy) on responses of erythrocyte electrophoretic motility (EPM) as a result of adrenoreceptor ligands binding (0.01-100 microM) has been investigated. The opposite directional EPM responses to agonists (adrenaline, isoprenaline) and antagonist (propranolol) of beta-adrenoreceptors was shown. At that, EPM response to the radiation coincides both with the direction and value of acting the beta-adrenoreceptor agonists depressing EPM. The EPM response to a combined action of beta-adrenoreceptors antagonist, propranolol (10 microM), and ionizing radiation is additive. The above listed is capable to evidence about the essential role of adrenoreceptors at formation of erythrocyte membrane surface charge under action of ionizing radiation in ultralow doses.     

Role of endogenous porphyrins in the effects of low-intensity laser radiation of the red region on free radical processes in the blood of rats under experimental endotoxic shock

The role of endogenous porphyrins in the effects of laser radiation of the red region (632.8 nm) on free radical processes in the blood of rats under endotoxic shock induced by the administration of lipopolysaccharide B (25 mg/kg) has been studied. The measurements of the functional activity of polymorphonuclear leukocytes (the method of luminol-dependent chemiluminescence), the superoxide dismutase activity of blood plasma (using nitro blue tetrazolium), and the degree of lipid oxidation of erythrocyte membranes (the method of fluorescence of cis-parinaric acid) have been carried out. It has been found that low-intensity laser radiation strongly affects all processes examined irrespective of the administration of lipopolysaccharide B. The effect of radiation was most pronounced in animals injected with the polysaccharide, the changes being dependent on the concentration of endogenous porphyrins in samples.     

Studies on the mechanism of radiation-induced structural disorganization of human erythrocyte membranes

The structural changes of human erythrocyte membranes after X-irradiation were investigated with the aid of fluorescent probes. It was found that the fluorescence characteristics (intensity, polarization and the dissociation constant) of 1-anilino-8-naphthalene sulphonate (ANS) bound to X-irradiated (up to 40 Gy) membranes were quite different from those in unirradiated ones. Sulphydryl (SH)-oxidizing reagents showed the same effects as X-rays on the ANS fluorescence. In addition, pretreatment of the membranes with SH reagents completely blocked the radiation-induced fluorescence changes. These results demonstrated that the initial cause of the radiation effect on membranes is the oxidation of membrane SH groups. There were two different steps in the development of the radiation effect on membrane structure; one is the radiation chemical reaction of SH groups, which is independent of the post-irradiation incubation temperature, and the other is markedly influenced by the temperature, particularly between 12 and 26 degrees C. Therefore it was concluded that structural disorganization of the membranes, including rearrangement of membrane components, might take place following exposure to radiation. This was supported by the fact that treatment with detergents mimicked the effect of X-irradiation. The reaction of OH and/or O2- from the aqueous environment was shown to be responsible for the membrane effect of radiation.     

Role of endogenous porphyrins in the effects of low-intensity laser radiation of the red region on free radical processes in the blood of rats under experimental endotoxic shock

The role of endogenous porphyrins in the effects of laser radiation of the red region (632.8 nm) on free radical processes in the blood of rats under endotoxic shock induced by the administration of lipopolysaccharide B (25 mg/kg) has been studied. The measurements of the functional activity of polymorphonuclear leukocytes (the method of luminol-dependent chemiluminescence), the superoxide dismutase activity of blood plasma (using nitro blue tetrazolium), and the degree of lipid oxidation of erythrocyte membranes (the method of fluorescence of cis-parinaric acid) have been carried out. It has been found that low-intensity laser radiation strongly affects all processes examined irrespective of the administration of lipopolysaccha-ride B. The effect of radiation was most pronounced in animals injected with the polysaccharide, the changes being dependent on the concentration of endogenous porphyrins in samples.     

Effect of gamma radiation on the transport of spin-labeled compounds across the erythrocyte membrane

Summary The effect of ionizing radiation on the non-electrolyte, anion and cation permeability of the erythrocyte membrane was studied by measurement of the reduction rate of appropriate nitroxyl derivatives. Irradiation of bovine erythrocytes in the dose-range of 2–50 krad resulted in a regular dose-dependent increase in the reduction rates of a cation (TEMPO-choline) and a hydrophobic non-electrolyte (TEMPO), and non-regular changes in the reduction rate of a hydrophilic non-electrolyte (TEMPOL). The permeation constant for TEMPO-choline also showed a non-regular response to radiation, similar to the response pattern of other red blood cell parameters. These results also demonstrate that the effects of radiation on the transport of various solutes can be used as a means of distinguishing between different channels of membrane transport.     

Phospholipid composition of blood erythrocytes of tundra voles (<Emphasis Type="Italic">Microtus oeconomus</Emphasis> Pall.) inhabiting under different radioecological conditions

Phospholipid composition has been studied in blood erythrocytes of tundra voles Microtus oeconomus inhabiting territories with normal and increased levels of natural radioactivity in different phases of the population cycle. It has been shown that rearrangement in the lipid component of blood erythrocyte membranes of tundra voles from radioactively polluted areas are associated with intensification of the lipid peroxidation (LPO) processes and are similar to those observed at the organism natural aging. It has been noted that the capability for peroxide oxidation in erythrocyte lipids is one of the most sensitive stages of the LPO processes to action of the low-intensity radiation in the natural habitat of animals. The change of the populational cycle phases, which is accompanied by hormonal rearrangements in the animal body, produces an essential effect on the degree of expression of the radiation-induced changes of the studied parameters.