The Effect of Polyene Antibiotic Amphotericin B on Erythrocyte Cytoarchitectonics and Osmotic Resistance.

We studied the effect of amphotericin B (2.5×10-5 and 5.4×10-5 M) on osmotic resistance and surface cytoarchitectonics of donor blood erythrocytes. Antibiotic at a concentration of 2.5×10-5 M induced most pronounced changes in the studied parameters, which can be related to the specifics of the spatial organization of the cholesterol-amphotericin B complexes at different stoichiometric ratios of the components and their ability to pore formation in the membranes. Cholesterol binding to the polyene antibiotic and the appearance of perforations in the plasma membrane lead to accumulation of reversibly and irreversibly deformed cells and their hemolysis. The appearance of a large number of irreversibly deformed erythrocytes indicates an impaired ability to elastic deformation in the microcirculatory stream, which can lead to disruption of their functions in vivo and intravascular hemolysis.

[The modification of structural and functional properties of human hemoglobin induced by nitroglycerin under different oxygen regime conditions]. / Modifikatsiia strukturno-funktsional'nykh svoistv gemoglobina cheloveka, indutsirovannaia nitroglitserinom, v usloviiakh razlichnogo kislorodnogo rezhima.

Human oxyhemoglobin exhibits high resistance to nitroglycerin during incubation of the protein with this compound for 0.3-3 h. Prolonged exposure (24 h) leads to activation of methemoglobin production. In the presence of nitroglycerin hemoglobin molecules undergo rapid oxidation during deoxygenation with formation of methemoglobin as the terminal product of human oxyhemoglobin interaction with nitroglycerin. The scheme of interaction processes of oxyhemoglobin with nitroglycerin in different conditions of oxygen regime is proposed. Partially deliganded hemoglobin plays the leading role in the initiation of hemoglobin oxidation processes.

[THE INFLUENCE OF NITROGLYCERIN ON SPECTRAL AND OXYGEN-BINDING CHARACTERISTICS OF HUMAN INTRACELLULAR HEMOGLOBIN.]

The spectral and oxygen-binding characteristics of human intracellular hemoglobin in the presence of nitroglycerin at concentrations of 5 ng/mL and 5 µg/mL have been studied. Short incubation (20 min) of erythrocytes with the drug led increasing hemoglobin affinity to oxygen and weakening of cooperative interactions in hemoprotein molecules. As a result, the amount of O(2) supplied to tissues in the process of gas exchange decreased by 23.96% (5 ng/mL) and 26.68% (5 µg/ml), p < 0.05. Incubation of cells for 24 h resulted in oxidation of the heme iron atom, accumulation of methemoglobin, and partial hemolysis. Nitroglycerin reduces the intensity of oxidative processes. However, no dependence of the degree of changes in the physical and chemical properties of hemoglobin on the concentration of nitroglycerin was found.

[Parameters of oxygen-binding function of human hemoglobin modified by carbon oxide and UV-light].

The parameters of oxygen-binding function of human hemoglobin, modified by carbon oxide and UV-radiation: the pressure of half-saturation with the ligand (P50), Hill's constant (n), and arterial-venous difference of HbO2 concentration in the sample were studied. The presence of carboxyform in blood in boundaries of admissible values (lower than 10 per cents) did not noticeably influence to the oxygenation parameters. Functional properties of hemoproteid were substantially modified in case of HbCO concentration increasing from 30 up to 80 percent. It has been discovered, that the leading mechanism of protection from hemic hypoxia in case of poisoning with CO is decreasing of degree of cooperative interactions and relative affinity of hemoglobin for ligands. The stimulating influence of UV-light to the functional properties of modified with carbon oxide human hemoglobin observed in case carboxyform hemoprotein concentration in solution was lower than 10 percent. The disturbance of oxygen-binding ability of hemoglobin at the influence of higher concentrations of Hb-CO was inconvertible and was not correct with UV-radiation.

[Change in spectral properties of nitrosohemoglobin induced by UV light]. / Izmeneniia spektral'nykh svoistv rastvorov nitrozogemoglobina, indutsirovannye UF-svetom.

The effect of UV radiation on the spectral characteristics of human nitrosohemoglobin in a wide dose range (151-4530 J/m2) was studied. It was shown that the irradiation of hemoprotein solutions with low doses of UV light (151-453 J/m2) led to local conformational rearrangements of the iron porphyrin moiety of the molecule. The apoprotein exhibited a high photostability under the conditions of the experiment. High doses of UV radiation (1359-4530 J/m2) induced the accumulation of methemoglobin in the protein sample. A scheme of the photoinduced formation of methemoglobin was elaborated.

[An assessment of the degree of chromophore photo damage to the heme and globin components in UV-irradiated molecules and electrophoretic fractions of human carboxyhemoglobin]. / Otsenka stepeni fotopovrezhdeniia khromoforov gemovogo i globinovogo komponentov UF-obluchennykh molekul i élektroforeticheskikh fraktsii karboksigemoglobina cheloveka.

The contribution of hem and globin components of electrophoretic fractions of UV-irradiated human carboxyhemoglobin to photodestruction of the protein was studied. The changes observed are the result of summation of some processes unequal in intensity and direction that take place in microheterogeneous media of photomodified protein. Photosensitivity of hemoproteid in electrophoretic fraction depends on apoprotein condition, whereas the hem photoresistance cannot be the evidence of the photostability of the whole molecule.