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Biomedical subjects

V K Lishko

Publications and source records attributed to V K Lishko.

At least 55 records · Page 3Linked to original sources
PubMed1977

[Identification of sodium channels in vitro].

The membrane fraction isolated from cattle brain and vagal nerve was treated by ultrasonic irradiation in the presence of 22Na. It was shown that 22Na was trapped in vesicles formed from sonicated membranes in an osmotically active forms and slowly released into a nonradioactive solution. The efflux of 22Na from vesicles was studied in the presence and in the absence of substances which change the sodium conductance of excitable membranes. The local anesthetics (procaine, dibucaine) and tetrodotoxin at concentrations blocking electrical excitation in vivo decreased the sodium efflux from the vesicles. Veratrine, an activator of sodium channels, increased this efflux. The results are interpretated as an indication of the presence of functionally active sodium channels in the isolated membrane fragments.

Anesthetics, Local↗
PubMed1976

[Study of ADP effect on brain Na+, K+-ATPase].

A mechanism of K-insensitive, ouabain-dependent liberation of Na+ from the cell during an increase in ADP intracellular concentration is studied. It is shown that the increase in the ADP/ATP ratio does not change the Na+, K+-ATPase affinity to K+ ions and does not result in the Na-activated, K-independent ATPase reaction. ADP protects ATPase from the inhibition by ouabain which is accounted for by a decrease in the concentration of a glycoside-sensitive form of the enzyme E2-P due to a turnover of the phosphokinase step of the reaction, but not due to the binding of free Mg2+ ions. The results obtained suggest that the increase in ADP concentration within the cell activates Na-Nan exchange along Na-transporting channels of the ionic pump.

Adenosine Diphosphate↗
PubMed1976

[Study of the interaction of Na+ and K+-ATPase of erythrocytes with ouabain. Effect of acetyl phosphate and p-nitrophenyl phosphate].

Effects of ATP, acetyl phosphate (AcP) and p-nitrophenyl phosphate (p-NPP) on the inhibition of the Na+, K+-ATPase activity were studied. ATP, AcP and p-NPP were found to facilitate the ouabain-induced inhibition of the enzyme activity only after the injection of these phosphorylyzing agents into the erythrocyte ghosts. Inside the ghosts Na+ ions enhanced the effects of the phosphorylyzing agents. K+ ions in the environment removed the stimulating effects of ATP, AcP and p-NPP on the ouabain-induced inhibition of Na+, K+-ATPase activity. It is concluded that the sites of AcP and p-NPP hydrolysis as well as the active center for ATP are localized on the inner surface of the cell membrane.

Adenosine Triphosphatases↗
PubMedDate not supplied

[Properties of artificial vesicles from biological membranes].

Ultrasonic treatment of microsome fraction or the preparation of partially purified Na+, K+-ATPase from cattle brain resulted in the formation of closed structures which immobilized rubidium and sodium ions and were easily discovered in electron microscope. Gradual release of bound rubidium ions was observed under the incubation of ultrasonic-treated membrane preparation in salt solutions. This process was activated by ATP. ATP-activated release of rubidium was observed only in the presence of sodium and was inhibited by ouabain. A hypothesis on the participation of sodium pump in the ion transport through membranes of artificial vesicles is discussed.

Adenosine Triphosphatases↗
PubMedDate not supplied

[Influence of detergents and inhibition of Na+,K+-ATPase and Mg2+ATPase on erythrocyte membrane SH-groups].

The article deals with the influence of sodium dodensylsulfate, lubrol and also of inhibition of Na+,K+-ATPase and Mg2+-ATPase activities by N-ethyl malemid on the form of curves of erythrocyte membranes amperometric titration by Ag+. It is shown that changes in a conformational structure of proteins membranes under the influence of detergents results in the transformation of SH-group of type I to SH-groups of type II. A 70% fall of Na+,K+-ATPase activity has the same result. So, the form of the curves for titration of erythrocyte membranes sulphydryl groups may serve as an indicator to the morpholocial and functional state of the membranes protein part.

Adenosine Triphosphatases↗
PubMedDate not supplied

[A high level of cytoplasmic calcium inactivates ion channels, formed by alpha-latrotoxin in the rat brain synaptosomes].

Effect of alpha-latrotoxin on the concentration level of free calcium [( Ca2+]in) in the rat brain synaptosomes and dependence of the activity of "latrotoxin" channels on [Ca2+]in were studied using fluorescent calcium probe quin-2. It is shown that alpha-latrotoxin exerts effect on calcium permeability of plasmalemma and does not induce calcium ejection from the intracellular compartments. A lag-period is characteristic of alpha-latrotoxin action. A degree of the [Ca2+]in increase in synaptosomes depends on the toxin concentration. When [Ca2+]in increases as a result of preliminary potassium depolarization of plasmalemma of synaptosomes, the amount of incoming calcium ions followed by the toxin effect as well as the calcium input rate considerably decrease. Inactivation of calcium-transferring channels induced by alpha-latrotoxin is not a result of a change in the potential on the membrane, as during the blockage of potential-depending calcium channels by D-600, an increase of KCl in the incubation medium does not influence the alpha-latrotoxin action. Differences in the properties of alpha-latrotoxin channels are discussed in synaptosomes and BLM.

Animals↗
PubMedDate not supplied

[Interaction of p-nitrophenylphosphate with Na+,K+-ATPase].

The vector characteristics of the interacting Na+, K+-ATPase and ouabaine were studied in experiments on the restored ghosts of erythrocytes. It is shown that the effect of K+ on the enzyme activity is the same as in cases of using ATP and p-nitrophenylphosphate (p-NPP) as phosphorylating agents. ADP removes the p-NPP induced inhibition with ouabain. This effect is explained rather by addition of ADP to the enzyme substrate centre than by a decrease in the concentration of E1 approximately P phosphoform. Incorporation of labelled orthophosphate into p-nitrophenol (NP) in the presence of Na+, K+-ATPase preparations was not detected. It is shown that antibodies against the fraction of the brain microsomes inhibit K+-NPPases to a much less extent than Na+, K+-ATPase. The digitonin treatment does not remove (Na++ATP)-dependent increase in the K+-NPPase activity. A conclusion is drawn that the mechanisms of p-NPP hydrolysis differs from the mechanism of ATP hydrolysis.

Animals↗
PubMedDate not supplied

[Transmembrane localization of cytosol proteins from the heart muscle in proteoliposomes].

It was shown that soluble cytoplasmic proteins of rabbit cardiac muscle were able to penetrate into phospholipid bilayer during preincubation with liposomes. The incorporation of cytoplasmic proteins into the liposomic membrane induced the sodium permeability that was sensitive to neurotoxins (veratridine and tetrodotoxin). This effect was partly eliminated by addition of tetrodotoxin to the external medium and completely eliminated in the presence of tetrodotoxin on the both sides of the liposomic membrane. It was found also that some of the proteins incorporated into the liposomes become resistant to pronase digestion when the enzyme is added to external medium. At the same time pronase included in the internal volume of the proteoliposomes was able to digest partly proteoliposomic proteins. All these data support the ideas of the integral incorporation of soluble cytoplasmic proteins into the liposomic membrane and to the existence of cytoplasmic precursor of voltage-dependent sodium channel.

Animals↗