Disorders in the Morphology and Nanostructure of Erythrocyte Membranes after Long-term Storage of Erythrocyte Suspension: Atomic Force Microscopy Study.

Disorders in the erythrocyte morphology and structure of their membranes during long-term storage of erythrocyte suspension (30 days at 4°C) were studied by atomic force microscopy. The morphology and nanostructure of erythrocyte membranes, biochemical parameters, ion exchange parameters, and hemoglobin spectra were recorded. The transformation of erythrocyte morphology and destruction of their membranes were observed throughout the storage period. Irreversible forms of spheroechinocytes and their fragments formed by the end of storage. The concentrations of potassium ions and lactate in solution of the blood preservatiive increased, while pH value decreased. Hemolysis detected by the erythrocyte "leakage" effect was observed starting from days 16-23 of storage.

Reversible zinc-induced injuries to erythrocyte membrane nanostructure.

Zinc-induced injuries to red blood cell membrane nanostructures at different zinc concentrations were studied by atomic force microscopy. In order to distinguish the intrinsic characteristics of membrane nanostructures, the membrane surfaces were represented by three orders using 3D Fourier transform. Increasing the concentrations of zinc ions modified the pattern of induced injuries: their depths and diameters and their number on the membrane surface test area increased. The injuries and their distribution for each order of membrane surface were analyzed. Albumin restored membrane nanosurface.

Macro- and microstructure of erythrocyte membranes under acute massive hemorrhage and subsequent blood reinfusion.

The authors studied changes in erythrocyte membrane nanostructure using a rodent model of hemorrhagic hypotension and resuscitation. Both macro- and microstructural elements were examined using atomic force microscopy. Membrane "roughness" was characterized using spatial Fourier transformation and was stratified according to the periodicity of the membrane. Acute hemorrhage resulted in an increase in the diameter and height of erythrocytes, which returned to baseline levels by the end of the hemorrhagic hypotensive period. The effect of hypotension on the erythrocyte surface was nonuniform. In those regions where damage was considerable, the rate of restoration of the membrane microstructure to baseline levels was prolonged. The less damaged surfaces were restored more rapidly to control values after reperfusion. More detailed use of atomic force microscopy in the definition of the erythrocyte membrane microstructure may further define the mechanisms of cellular functional restoration after hemorrhage.

Erythrocyte membrane surface after calibrated electroporation: visualization by atomic force microscopy.

Atomic force microscopy was used for examination of the surface of human erythrocyte membrane after calibrated electroporation and application of pharmacological agents. Three-order surface inhomogeneities were revealed with various spectral windows of Fourier transform to elaborate the quantitative criteria to assess the state of membrane surface. The size of structural alterations induced in the membranes by electroporation was 100-300 nm, which is comparable to the size of membrane matrix.

[The diagnostic of membranes' state after exposure of gamma-radiation of small doses].

There are the results of experimental research of the change of membranes' conditions under the action of gamma-radiation using the method of following membranes' electroporation of the accurate impulse of the electrical field for the analysis of defects after the action of gamma-radiation. As of the research material the suspension of erythrocytes was used. It was shown that the velocity of decreasing of the erythrocytes in the case of combined action of gamma-radiation and the impulse of the electrical field is more than the sum of such velocities in the case of the action of the factors separately. The method of the electroporation of the accurate impulse of the electircal field is obvious for the practicaland the analytical research of membranes' defects.

Effect of defibrillation pulses of different shapes on biomembranes: experimental study.

We studied the effects of high-voltage single, double unipolar, and double bipolar electric pulses of exponential or sine shape on erythrocyte membranes. Either single or double (mono- or bipolar) pulses were used. All pulses electroporated the membranes, and the electroporation threshold did not depend on the pulse shape. Two successive pulses decreased erythrocyte number in a nonadditive way. Similar to defibrillation of the whole heart, the effect of two bipolar pulses on erythrocytes was more pronounced than the effect of two unipolar pulses.

[Spatio-temporal changes in the metabolic processes in the blood-tissue system in the terminal states of the organism]. / Prostranstvenno-vremennye narusheniia protsessov obmena v sisteme krov'-tkan' pri terminal'nykh sostoianiiakh organizma.

The role of synergism in diffusion of oxygen from erythrocyte into interstitial liquid and water filtration through the capillary wall was studied on the model using the following parameters: hydrostatic pressure on arterial and venous ends of the capillary (Pa and Pb), oncotic blood and tissue pressure (Pob and Pot), pore radius in the capillary (r), the number of pores in the capillary (n) per m2, amount of the liquid released from the capillary (q(x)), gas diffusion coefficient (D), time of erythrocyte movement in the capillary (T), speed of oxygen consumption (V), maximal distance with adequate V (Xmax), characteristic time of diffusion (Topt). It is shown that diffuse and convective components of the metabolic process have their own contribution and in changed conditions they redistribute. In increased number and diameter of hydravlic pores the greatest role in tissue saturation with oxygen belongs to convective metabolism, but in this situation tissues contain areas lacking oxygen.

[The shape of high-voltage impulse and the effect of defibrillation]. / Vliianie formy vysokovol'tnogo impul'sa na éffekt defibriliatsii.

The paper discusses how to choose the optimum shape of a pulse for electric defibrillation of the heart. The authors' data are given on the values of an induced field in the contracting myocardial structure when a defibrillator evokes pulses. Mono- and bipolar pulse-induced changes of the transmembranous potential on the hyper- and depolarized sides of a cell are calculated. Mechanisms of defibrillation in the use of pulses of different shapes are considered.

Modeling of blood flow as the result of filtration-reabsorption processes in capillaries.

In our previous article (Am J Physiol Adv Physiol Educ 272: S26-S30, 1997) we proposed a model that permits analysis for the change of hemodynamics in vessels with local stenosis. This problem is connected with the blood-tissue metabolism. This article continues the classroom research on concepts related to blood flow physiology. We take into consideration the problem of the blood-tissue fluid exchange. A model based on basic principles of hydrodynamics and mathematics is proposed for analysis of "filtration-reabsorption equilibrium" and its disturbances under different external influences. It permits medical students to develop a scientific analytic approach to the solution of physiological and pathophysiological hemodynamics problems.

[A model of blood flow distribution during filtration-reabsorption processes in capillaries]. / Modelirovanie raspredelenie krovotoka pri fil'tratsionno-reabsorb tsionnykh protsessakh v kapilliarakh.

A model of blood flow in a capillary was constructed, which takes into account the movement of plasma through its porous wall. The functions of changes in pressure and the rate of blood flow along the capillary were calculated. It was shown that, in the general case, the distribution of hemodynamic parameters as a result of filtration-reabsorption processes is nonlinear. Possible mechanism of tissue edema resulting from the disturbance of the filtration-reabsorption equilibrium were analyzed.

[Exponential distribution of interimpulse current intervals in lipid bilayer membrane at phase transition temperature]. / Eksponentsial'noe raspredelenie mezhimpul'snykh intervalov toka v bisloinykh lipidnykh membranakh pri temperature fazovogo perekhoda.

The statistical analysis of current fluctuations in unmodified bilayer lipid membranes at the phase transition temperature was made. An exponential distribution of current fluctuations was revealed.

[Lipid pores and life time of lipid bilayer membranes in gel and liquid crystal states]. / Lipidnye pory i vremena zhizni bisloinykh lipidnykh membran v gel'- i zhidkokristallicheskom sostoianiiakh.

The lifetime of lipid bilayer membranes formed from hydrogenated egg lecithin has been studied at the phase transition from liquid crystalline state to the gel. It was shown the lowering of the membrane stability at the phase transition temperature of hydrogenated egg lecithin. Using lifetime values and measured surface tension of bilayer the critical radius of transmembrane pore has been evaluated in comparison with experimental data, obtained by transmembrane current fluctuation registration. It was shown that lifetimes of bilayer lipid membrane in gel state conform data, derived from Deryagin-Gutop-Prokhorov's theory. The radii of pores corresponded to maximal transmembrane current fluctuations are close to critical values of pores in the gel state.

[Fibrillation of the heart ventricles]. / Fibrilliatsiia zheludochkov serdtsa.

During ventricular fibrillation, extra feedback may form in the myocardial structure due to specific features of such fibrillation, specifically, because of highly asynchronous contractions of some parts of the myocardium; these newly forming feedback is conducive to a persistent development of such arrhythmia. The frequency of the waves of mechanical contractions in various segments of the myocardium varies depending on the increase of hypoxia. The waves do not correlate with each other as regards their shape, neither do they correlate with the electrical activity waves. This indicates the complex nature of the mechanisms giving rise to and maintaining ventricular fibrillation. Study of the electromechanical correlations in the myocardium, observed in ventricular fibrillation, and analysis thereof together with the complex staged development of ventricular fibrillation may help better understand the pathological processes in the myocardium and, hence, enable us to develop effective methods to control it.

[The mechanism of the occurrence of segmental stress nonuniformities in the left ventricle during disordered excitation processes]. / Mekhanizm vozniknoveniia segmentarnykh neodnorodnostei napriazhenii v levom zheludochke pri narusheniiakh protsessov vozbuzhdeniia.

Intramural tension of the heart left ventricular wall and top, intracavity pressure and the ECG were measured in anesthetized dogs. Appearance of a ventricular excitation centre was shown to cause a tension in one of the segments and its simultaneous drop in another one. The intracavity pressure could remain unchanged due to the mechanism of complete compensation. Conditions of appearance, quantitative and qualitative estimation of sizes and geometry of zones of abnormal contractions in the segments, were determined.

[The segmental contractility of the left ventricle in disorders of the cardiac rhythm]. / Segmentarnaia sokratimost' levogo zheludochka pri narusheniiakh serdechnogo ritma.

The contractility of the left ventricular wall (LV) and apex of the heart has been recorded by means of intramural probes in a series of experiments on dogs. Pressure in the heart, stroke volume and ECG were measured. Arrhythmias appeared in response to epinephrinum and ephidrinum administration. The raising strength in the apex during parasystole was accompanied by simultaneous decrease in the strength of the ventricular wall, no alterations in the hemodynamics were recorded. During precordial block the raise of the stroke volume was due to the raising strength of the ventricular wall contraction, the strength of the apex contraction remaining unchanged. The strength redistribution shown might be the cause of destructive changes in the myocardium.

[The specific nature of the nonuniformity of muscle tensions in different sections of the heart under the action of inotropic factors]. / Spetsifichnost' neodnorodnosti myshechnykh napriazhenii v razlichnykh otdelakh serdtsa pri deistvii inotropnykh faktorov.

In anesthetized dogs, changes of tensions due to the effect of CaCl2 solution were studied in the left ventricle's wall and the heart apex. Hemodynamic parameters, ECG and intramural tension were recorded. The tension forms looked different in the wall and the apex at normal cardiac contractions; they changed in different ways under the effect of inotropic factors. The latters could induce three types of the amplitude non-uniformity in the left ventricle's wall and in the apex, depending on the drug and its dose. The non-uniformity type for a separate heart is specific in respect to administered drug. The non-uniformities at large doses of inotropic factor exceeding normal physiological levels, are regarded as an additional mechanism of the heart stability under considerable loads.

[Features of contraction of various sections of the left ventricle of an intact heart upon the action of inotropic factors]. / Osobennosti sokrashcheniia razlichnykh otdelov levogo zheludochka intaktnogo serdtsa pri deistvii inotropnykh faktorov.

In anesthetized dogs, the effects of adrenaline and CaCl2 were studied by means of measuring intramural tension in the left ventricle wall (LV) and in the apex. The inotropic effect involved an increase in the ratio between the velocity of the tension growth in isovolumic phase and the maximum tension of this contraction, the ratio increasing more slowly in the apex than in the LV. This can be due to that the inotropic factors induce a greater growth of intramural tension in the apex than in the LV.

Mechanisms of electrical defibrillation of the heart.

This paper discusses the development of theoretical models of heart defibrillation by a bipolar impulse. These are based on theoretical mechanisms as well as our results obtained in a series of fibrillation/defibrillation experiments carried out in anesthetized mongrel dogs. The procedures for fibrillation and defibrillation have been previously described. During the experiments, blood pressure, ECG, and ventricular wall contraction strength are continuously recorded. The methods of recording have been previously described.