[Modulation of voltage-gated sodium channels by recombinant interferon-alpha2b in the human neuroblastoma cell line IMR-32].

Clonal human neuroblastoma cells imr-32 are a suitable model system for studies of neuronal excitability modulation. The ability interferon-alpha 2b "laferon" to modulate the mechanisms of electrical activity was studied in whole-cell patch-clamped undifferentiated human neuroblastoma cells IMR-32. It was shown that 1 h incubation of IMR-32 cells at 37 degrees C in medium with laferon (600 U/ml) exerted changes in voltage-dependent properties of Na(+)-channels.

[The Ca2+-activated photoprotein obelin as a calcium transport inducer in proteoliposomes in the membrane of the T-system of skeletal muscles].

The calcium-binding photoprotein obelin extracted and purified from the luminescent hydroid Obelia longissima was used to record the processes of Ca2+ release from proteoliposomes. It has been shown that lecithin proteoliposomes with incorporated rabbit skeletal muscle T-system membranes possess a BAY K-8644-activated permeability which is inhibited by nitrendipine. The Ca(2+)-activated photoprotein obelin is a convenient and perspective tool in studies of fast calcium fluxes.

[Calcium transport in proteoliposomes incorporating membranes of skeletal muscle T-system].

Using the radioisotope method, the Ca2+ transport through proteoliposomes was investigated. The proteoliposomes originating from total brain lipids and skeletal muscle T-system membranes of the rabbit were shown to possess a Ca2+ permeability which can be stimulated by 1.4-dihydroxypyridine derivatives (10(-9)-10(-7) M).

[Effect of amiloride on the activity of membrane-bound and soluble Na+-,K+-ATPase preparations].

Amiloride (8 X 10(-4), an inhibitor of sodium channels of nonexcited membranes, inhibits the activity of Na+,K+-ATPase in the kidney cortex homogenate as well as that of the partially purified membrane-bound and lubrol-soluble Na+,K+-ATPase preparations from the cattle brain. Inhibition of Na+,K+-ATPase from different organs of various animals by amiloride, a blocker of sodium channels, indicates similarity of the molecular organization of the Na+-recognizing component both of sodium channels and sodium centres of Na+,K+-ATPase.

[Incorporation of Na,K-ATPase into human erythrocyte membranes using liposomes].

A procedure for incorporation of isolated cattle brain Na,K-ATPase into erythrocyte membranes by proteoliposomes has been elaborated. The Na,K-ATPase activity of proteoliposome-treated human erythrocytes containing incorporated Na,K-ATPase does not exceed that of control erythrocytes. In the erythrocyte membrane the incorporated enzyme exists in a functionally active state and retains the vector properties of the Na+-pump.

[Lipid composition of different preparations of brain Na+, K+-ATPase].

The content and composition of phospholipids is determined in beef microsomal and synaptosomal fractions and also in these fractions preparations solubilized with triton X-100 (0.1%) and digitonin (0.2%).

[Sodium pump reconstruction in lipid vesicles].

Reconstitution of purified lubrol-solubilized preparation of Na,K-ATPase from the calf brain was performed in liposomes and transport characteristics of this system were investigated. The system was demonstrated to preserve vectoral features of the sodium pump. Addition of ATP to the medium evoked active influx of sodium and efflux of rubidium in proteoliposomes.

[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.