Biomedical subjects

A B Kaulin

Publications and source records attributed to A B Kaulin.

11 recordsLinked to original sources

PubMed1991

[Changes in the membrane potential, the cytoplasmic Ca2+ concentration and in the transport of fluorescein anions across the macrophage plasma membrane under the influence of O2(-) and H2O2 in small concentrations].

It has been shown that under the influence of superoxide anion (300 nM) and hydrogen peroxide (100 nM) on murine peritoneal macrophages, the depolarization of membrane takes place, and a change in the rate of fluorescein anion efflux from the cells occurs. Hydrogen peroxide (but not superoxide anions) causes a transient increase in the cytoplasmic Ca2+ concentration. These changes are regarded as early signs of macrophage activation. It is assumed that macrophage activation with reactive oxygen intermediates at such a low concentration might be interpreted as follows: a small portion of stimulated phagocytes activates the whole population with the aid of the products of their own oxidative burst.

Animals↗

PubMed1991

[The measurement of the macrophage membrane potential by using an oxonol fluorescent probe].

Technical questions of macrophage (MP) membrane potential measuring with a probe bis(1,3-dibutyl barbiturate) trimethineoxonol (diBA-C4 (3)) have been elaborated. Measurements were made of single adherent cells. It was shown that at a high concentration of probe in the medium (900 nM) the fluorescent signal well traces the depolarization of membrane, whereas at a low concentration of probe (110 nM) the hyperpolarization is detected more effectively. To find out the reasons for this difference, measurements were made of dye distribution between the cell and the medium measured as well as of the kinetics of probe efflux from MP in the dye-free medium. The gradient of dye concentration on the cell-medium interface appeared to depend on the concentration of diBA-C4 (3) in the medium. Using gramicidin D and Na- and Cl-free solutions, the calibration of fluorescent signal was done; the value of K+ equilibrium potential of MP was -66 - -71 mV. The effect of quinidine and the binding of intracellular calcium result in a significant depolarization of MP membrane; a conclusion is made of the significant contribution of Ca(+)-dependent K(+)-channels to the maintenance of the MP resting potential.

Animals↗

PubMed1991

[Macrophage activation by synthetic peptides. III. Changes in the membrane potential, Ca2+ content and the regulatory decrease of macrophage volume under the action of tuftsin and its antagonist].

With the use of oxonol voltage-sensitive fluorescent dye it has been shown that the stimulation of macrophages (MP) with tuftsin results in a two-phase change in membrane potential: depolarization followed by hyperpolarization of plasma membrane. The pattern of changes in membrane potential depends on Na+ concentration in the medium and is disturbed with binding of cytoplasmic Ca2+. Fluorescent signal obtained from MP loaded with Ca(2+)-activated photoprotein obelin points to a significant increase in the concentration of cytoplasmic Ca2+ under the influence of tuftsin on cells: the source for Ca2+ being the medium. The rate of regulatory voltage decrease in MP increases under the influence of tuftsin: the effect of this peptide being similar to that of calcium ionophore. All these findings taken together enable us to suggest a phenomenological scheme of transmembrane ion signals arising during stimulation of MP with tuftsin: the receptor-mediated calcium channel provides a rise in cytoplasmic Ca2+ which opens non-selective cation channels for Na+ ions to activate eventually Ca(2+)-dependent K(+)-transport.

Animals↗

PubMed1989

[Macrophage activation by synthetic peptides. II. The effect of oxidative burst products on the fluorescence kinetics of macrophages stained with fluorescein diacetate].

Our previous study has shown that the intensity of macrophages in a medium containing fluorescein diacetate (FDA) retains a certain constant level ready to fall upon the addition of stimulants. The decrease in fluorescence was attempted to explain by secretion of oxygen metabolites during the activation process. The decrease in fluorescence is much smaller in the medium containing catalase and superoxide dismutase. Hydrogen peroxide (50 nM and higher) causes a reversible decrease in the fluorescent intensity of resting macrophages. These experiments suggest that the oxidative burst products may serve as regulators of the feedback control during macrophage activation.

Animals↗

PubMed1989

[Macrophage activation by synthetic peptides. I. Kinetic changes in the transport of fluorescein anions across the plasma membrane of macrophages].

As shown by cytofluorimetric technique, fluorescein anions formed in macrophages due to hydrolysis of fluorescein diacetate (FDA) release into the extracellular medium through the probenecid-inhibitable transport system of organic acids. Technical procedures have been elaborated to record separately the process of FDA hydrolysis characterising the activity of intracellular esterases, and the fluorescein anion transport representing secretion of organic acids by macrophages. It has been established that the tetrapeptide tuftsin stimulates the cell esterase activity without affecting the rate of fluorescein efflux. The peptide KPR (Lys-Pro-Arg) decreases both the esterase activity and the fluorescein anion efflux.

Amino Acid Sequence↗

PubMed1978

[Fluorescence anisotropy and myelin structure. II. Azimuth characteristic of surviving nerve fibers].

The dependence of fluorescence polarization of stained nerve fibres on the angle between the fibre axis and electrical vector of exciting light (azimuth characteristics) has been considered. Evidence is provided that the azimuth characteristics of stained nerve fibres depends on dye molecules adsorbed on the myelin sheath membranes. From the previous calculations it may be concluded that part of the dye molecules are oriented at a small angle to the geometrical axis of the nerve fibre.

Animals↗

PubMed1978

[Fluorescence anisotropy and myelin structure. III. Effect of temperature changes on the orientation of dye molecules in nerve fibers].

The temperature dependence of fluorescence polarization of stained nerve fibres has been studied. As has been previously demonstrated by the authors, the dependence of fluorescence polarization on the angle between the electrical vector of exciting light and the fibre axis (azimuth characteristics) is associated with the molecular orientation of dyes adsorbed on the membranes of the myelin sheath. This permits an indirect conclusion to be made about the structure and structural changes of an adsorbent. The experiments with changing temperature show that the molecular orientation of dyes decreases with decline of temperature from the room temperature to the freezing point of the Ringer solution. The structure of myelin membranes is suggested to be stabilized through hydrophobic interaction.

Acridines↗

PubMed1977

[Properties of cell water].

An attempt was made to analyse and summarize findings concerning water properties of animal and plant cells. From the physical evidence of surface influence on the structure of vicinal water layers, a conclusion is drawn that the structure and properties of cell water are likely to be affected by intracellular interfaces.

Animals↗

PubMed1977

[Fluorescence anisotropy and the structure of myelin. I. The theory of the method].

Theoretical aspects of the experiment dealing with measurements of fluorescence polarization degrees in stained myelinated nerve fibres are considered. Fluorescence polarization (FP) largely depends on the excitation azimuth, i.e. on the angle between the electrical vector of the polarized exciting light and the nerve fibre axis (geometrically it is a figure with the cylinder symmetry). The dependence of FP on the excitation azimuth is shown to be related to the degree of molecular orientation of dyes adsorbed on anisotropic layers of myelin membranes. This permits to associate FP with the structural changes of myelin membranes.

Animals↗

PubMed1976

[Cooperative sorbtion of trypaflavin by glycerinized muscle fibers. I. Adsorption isotherm and changes in the fluorescence polarization of the sorbed dye].

The equilibrium binding of a fluorescent cationic dye Tripaflavine (TPF) by frog's glicerinated mucle fibres is described by a S-shaped isotherm: the Langmuir sorption at low dye concentrations in the medium (0.84-10-5--3.38-10-5 M) is followed by the cooperative binding with the increase of concentration (8.45-10-5--338.0-10-5 M). The appearance of new TPF binding centres, alteration in fluorescence anisotropy of sorbed dye as well as inactivation of myosine ATPase of model fibres at high concentrations indicate that the cooperative phase of sorption is characterized by changes in the structure of contractile proteins.

Acriflavine↗

PubMed1976

[Effect of various antimicrotubular drugs on the osmotic water flow through the wall of frog's urinary bladder].

The action of antimicrotubular drugs (colchicine, vinblastine and copper) on the osmotic water flow through the wall of the urinary bladder of Rana temporaria has been studied. The osmotic gradient was made by five- or tenfold dilution of the internal Ringer solution. The water flow was estimated gravimetrically. The water flow was induced by pituitrin (50 milliunits/ml), cyclic AMP (cAMP, 0.5-10(-3) M) and nystatine (3.5-10(-5) M). Pituitrin and cAMP and all the antimicrotubular drugs were added from the serosal surface of the bladder. Nystatine was introduced with the help of a fixed polyethylene tube. Preincubation with colchicine lasted 4 hours and that with vinblastine and copper (CuSO4), 1 hour. The drug concentrations varied between 10(-5)--10(-4) M. All the drugs studied showed a significant inhibitory effect toward pituitrin. The action of cAMP on the water flow was seen inhibited in the presence of colchicine and copper. The nystatine induced water flow was supressed by copper, colchicine being in this case inactive. A conclusion is drawn that the inhibition of cAMP formation does not cause a decreased pituitrine effect in the presence of antimicrotubular drugs. It has been assumed that the microtubules may be involved in the directed water flow within the cell.

Animals↗