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Biomedical subjects

A S Shevchenko

Publications and source records attributed to A S Shevchenko.

At least 37 records · Page 2Linked to original sources
PubMed1980

[Changes in acetylcholinesterase and ATPase activity and certain structural features of the erythrocyte membrane in experimental myocardial ischemia].

Acute heart ischemia induced by ligation of the left coronary artery is associated with variation in the activity of acetylcholinesterase, Na, K-ATPase and Ca, Mg-ATPase in rat erythrocytes. The maximum pronounced variations in the enzymatic activity and in the membrane capacity of erythroblasts for binding direct turquoise are recorded on the 7th day of the experimental myocardial infarction.

Acetylcholinesterase↗
PubMed1978

[The effect of membrane-bound calcium on the activity of adenosine triphosphatase from erythrocytes and erythrocyte permeability for monovalent cations].

The activities of Ca2+, Mg2+-ATPase and Na+, K+-ATPase and the permeability of reconstituted human erythrocytes for Na and K ions were measured, using Ca2+-EGTA, Ca2+ATP and Ca2+-sodium citrate buffers. It was found that the increase in the Ca2+/chelate ratio caused stimulation of Ca2+, Mg2+- and Na+, K+-Atpases and an increase in the rate constants of ouabain--dependent 42K+ influx and 22Na+ efflux from the erythrocytes. The use of the Ca2+-sodium citrate system as a calcium buffer did not change the parameters of the functional state of erythrocyte membranes. The data obtained are discussed in terms of a possible role of calcium ions, which are bound to the inner surface of the erythrocyte membrane, in the regulation of the systems of active and passive transport of cations.

Adenosine Triphosphatases↗
PubMed1978

[Role of membrane-bound calcium in changes in the ATPase activity, permeability and structural state of human erythrocyte membranes].

A study was conducted on the reconstituted erythrocytes obtained by the method of fast reversible hemolysis. The concentration of free Ca2+ ions in the reconstituted erythrocytes was supported by Ca-EGTA and Ca-nitrate buffers. Oubain-uninhibited ATPase component with a high affinity for Ca2+ (K0.5=4 micron) and alteration of passive and active K+-permeability in the region of free Ca2+ concentration up to 10 micron could be determined only when the content of membrane-bound Ca+ varied. Depletion of the inner side of the membrane of reconstituted erythrocyte is accompanied by alteration of hydrophobic character of the hydrocarbon region of the membrane. It is suggested that Ca+-induced alterations in the structure of the erythrocyte membrane may be a direct cause of the alterations in ATPase activity with a high Ca2+ affinity and permeability for univalent cations.

Adenosine Triphosphatases↗
PubMed1977

[Characteristics of Ca2+ ion effect on the activity of Mg2+-dependent ATPase system in ghosts and reconstituted erythrocytes].

A good conformity if demonstrated of the kinetics of calcium ions effect on ATPase activity of human and rat erythrocyte ghosts. The increase of calcium concentration in the rat errythrocytes hemolysis medium (above 50-100 micrometer) results in a considerable aggregation of reconstructed vesicles. An activation of ouabaine-sensitive component of Mg2+-dependent ATPase under the increase of intracellular Ca2+ in reconstructed human erythrocytes is observed.

Adenosine Triphosphatases↗
PubMed1977

[Changes in calcium ion binding and characteristics of Na+, K+-ATPase functioning in erythrocytes in the presence of hypertension].

A greater amount of calcium is removed with the aid of EDTA from the erythrocyte membranes of patients with hypertensive disease than from erythrocytes of persons with a normal arterial blood pressure. When isotonic MgCl2 was used the amount of calcium removed from the erythrocytic membrane was equal in both groups. The activity of Na-K-ATP-ase in the membrane of reconstituted erythrocytes increased with the action of calcium ions in the patients with hypertensive disease only half as much as in healthy persons.

Adenosine Triphosphatases↗
PubMed1976

Evidence of altered permeability of the erythrocyte membrane for sodium and potassium ions in spontaneously hypertensive rats.

1. Erythrocyte membrane permeability to sodium and potsssium ions was studied in 8-10 weeks spontaneously hypertensive rats (SHR, Kyoto/Wistar strain), normotensive Wistar and Sprague-Dawley rats. 2. The rate of 22Na efflux from the erythrocytes and the rate constant of Na/Na exchange were considerably greater in SHR than in normotensive Wistar and Sprague-Dawley rats. This difference remained the same in rats adrenalectomized 7 days before the experiment. The maximum difference in the constants was found when the sodium-potassium pump was blocked by ouabain. 3. The accumulation of 42K in the erythrocytes of SHR (the sodium-potassium pump being blocked) took place at a considerably slower rate, and the K+ wash-out into a potassium-free medium was faster than that in the normotensive Wistar and Sprague-Dawley rats. 4. These results indicate a higher permeability of the erythrocyte membrane of SHR for Na+ and K+, compared with normotensive Wistar and Sprague-dawley strains. It is suggested that this may reflect a more widespread cell-membrane defect, which could serve as a general cause for activating the mechanisms maintaining high blood pressure.

Animals↗
PubMed1976

[Study of the structural lability of biomembranes and their components by the fluorescent analysis method. IV. Kinetic characteristics of the binding of unsaturated fatty acids with bovine serum albumin].

By studying fluorescent parameters of ionic and neutral probes the kinetics of complex formation between the molecules of bovine serum albumin (BSA) and unsaturated fatty acids was investigated. The following regularities were observed: 1. Unlike the saturated fatty acids the unsaturated ones changed fluorescent parameters of the probes according to the cooperative mechanism, significantly decreasing the quantum yield values; 2. Temperature dependence of the fluorescence of both probe types in the complexes BSA -- oleic acid and BSA -- linole acid shows some bends at t=30--39 degrees C for which the lipid components is responsible.

Anilino Naphthalenesulfonates↗
PubMed1976

[Disruption of erythrocyte membrane permeability for sodium and potassium ions in hypertension].

The kinetics of Na22 efflux from the erythrocytes and K42 accumulation by the erythrocytes in patients with essential hypertension and in normotensive persons was studied. Sodium efflux from the erythrocytes into a normal medium was found to be significantly accelerated in hypertensive patients, and their rate constant of Na/Na exchange in the erythrocytes has a higher value (1.61 +/- 0.39 mol.1(-1) min.-1 versus 0.56 +/- 0.08 - 10(-6) mol. 1(-1).min. -1). The difference is statistically significant only under active transport inhibition with ouabain. K42 accumulation by the erythrocytes is slower than in normotensive indifiduals. The observed changes in the transport of cations are attributed by the authors to an increased passive permeability of the erythrocytic membrane in hypertonics. The latter is interpreted as a fragment of a more general defect of the cell membrane function that may be the cause of activation of the mechanisms that maintain a high arterial pressure.

Adult↗
PubMed1975

[Disorder of erythrocyte membrane permeability in spontaneous genetic hypertension in rats].

The efflux of 22Na from erythrocytes of spontaneously hypertensive rats (SHR) and the ones of Wistar and Spra glue-Dawley aged 8 weeks was studied. The efflux rate of the isotope from erythrocytes with ouabaine blocked active transfer of ions was much higher in the SHR in the prehypertensive and early hypertensive stages than in Wistar and Sprague-Dawley rats. These data suggest that, by comparisons with the Wistar and Sprague-Dawley the SHR have an elevated passive permeability of the erythrocytes membrane to sodium. The authors consider this fact as a possible indication of the presence in spontaneous hypertension of a more extensive defect of the membranous permeability which can prove to be a major cause responsible for activation of servomechanisms that keep up the arterial pressure at a high level.

Animals↗
PubMed1975

[Characteristics of erythrocyte membrane permeability for potassium ions in rats with familial spontaneous hypertension].

The kinetics of 42K influx into the erythrocytes was studied in spontaneously hypertensive rats (SHR) during the prehypertensive and early hypertensive stages (aged 10 weeks), as well as in Wistar and Sprague-Dawley rats of the same age. The SHR displayed a significantly slower enhancement of the activity in the erythrocytes than in the Wistar and Sprageu-Dawley rats, which indecates a higher level of passive permeability of the erythrocytic membrane for potassium ions and an enhanced turnover of this ion in the erythrocytes of SHR. The revealed changes are interpreted as a fragment of a larger defect in the membrane of SHR that determines the development of spontaneous hypertension.

Animals↗
PubMedDate not supplied

[Fluorescence analysis study of the structural lability of biomembranes and their components. I. Bovine serum albumin].

The binding constants, quentum yield and temperature dependence of the fluorescence of ionic (1-anilinonaphtalin-8-sulphinate) and neutral (N-phenyl-1-naphtylamine) probes were studied on the molecules of bovine serum albumine with the change of pH and solution ionic strength. On the basis of the data obtained the nature of sorbing forces and structural properties of the albumine molecule concerned are discussed.

1-Naphthylamine↗
PubMedDate not supplied

[Fluorescence analysis study of the structural lability of biomembranes and their components. II. Higher fatty acids].

Binding constants, quantum yield and temperature relationship of the fluorescence of ionic (1-anilinonaphtalene-8-sulphonate-ANS) and neutral (N-phenyl-1-naphtalamine-PNA) probes have been studied on micellae and ufasomes of natural fat acids. The following regularities have been obtained: 1. The Anion dye (ANS) sharply decreases the intensity of fluorescence on fat acid structures while alkilating the medium, it is not practically bound with them at pH-7; 2. The neutral dye (PNA) shiws no fluorescence on micellae of the limited fat acids and is comparatively well bound with urasomes. The binding constant quantum yield of PNA fluorescence significantly decreases during the transition from the ufasomes of oleic acid to those of polyunsaturated fat acids. 3. The temperature relationship of PNA fluorescence intensity sorbed on oleic acid ufasomes shows twists in the region of 16--20degreesC and 46--52degreesC. The first transition is connected with the melting of potassium oleate.

1-Naphthylamine↗
PubMedDate not supplied

[The effect of increased levels of chronic UVB-radiation on the functional state of the body in sheep].

The effect of increased doses of UV-B-radiation produced by LER-40 lamps (with an intensity of 5.5 W/m2 at a daily dose of 20 kJ/m2 and a total dose for 15 days of 300 kJ/m2) on the cardiovascular function, biochemical, biophysical and structural parameters of blood plasma and cells of sheep was investigated. It was found that increased UV-B-radiation produced functional changes in different physiological systems of animals: arrhythmias, diastole shortening, increase of the systole-diastole index; decrease of platelet count, shortening of blood coagulation time; increase of calcium, iron and copper and decrease of zinc in plasma; conformational changes in cytoplasmic membranes of platelets and lymphocytes. The changes that occurred in the sheep at an early stage of exposure can be viewed as adaptive. However, functional changes that were seen at remote stages suggested that the sensitivity of various systems of the body to UV-B-radiation was different.

Animals↗