[Modulation of voltage-gated sodium channels by recombinant interferon-alpha2b in the human neuroblastoma cell line IMR-32]. / Moduliatsiia potentsiialupravliaemykh natrievykh kanalov kletok neiroblastomy cheloveka IMR-32 pri deistvii rekombinantnogo interferona-alfa2b.

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 results of the present study demonstrate that laferon decreased of Na(+)-channels sensitivity to changes of membrane potential leading of IMR-32 cells electrical excitability decrease.

[Surface charge of the cytoplasmic side of the cell membrane of neuroblastoma in murine line C1300]. / Poverkhnostnyi zariad tsitoplazmaticheskoi storony membrany kletok neiroblastomy myshi linii C1300.

Inside-out vesicles were obtained from the cell membranes of murine neuroblastoma. The surface charge of vesicles was studied by the microelectrophoresis method. At neutral pH they had the electrophoretic mobility 2.7 times less than right-side-out vesicles. Neuraminidase treatment reduced the mobility of right-side-out vesicles, while that of inside-out was unchanged. Treatment with trypsin resulted in a decrease of the mobility of both types of vesicles. Treatment with phospholipase C decreased the mobility of inside-out vesicles, but did not influence that of right-side-out ones. Treatment with phospholipase D increased the mobility of both types of vesicles. In the low pH solution the mobility of inside-out vesicles decreased with respect to titration of acidic groups with intrinsic pK 3.5. The mobility of inside-out vesicles depended on Ca2+ concentration.

[Relation between the surface potential of mouse neuroblastoma clone C1300 cells and the phase of the cell cycle]. / Zavisimost' poverkhnostnogo potentsiala kletok neiroblastomy myshi klona C1300 ot fazy kletochnogo tsikla.

The surface charge of neuroblastoma cells in different phases of the cell cycle was studied by the microelectrophoresis method. The surface charge increased by 50% on the average after addition of colchicine to the culture medium, by 20-30% after addition of dibutyryl-cAMP or removal of the serum from the medium and decreased by 30% after addition of DMSO. These changes correlated well with variations of the protein content per cell.

[Surface charge of mouse neuroblastoma cells and changes during growth and morphologic differentiation of the cell population]. / Poverkhnostnyi zariad kletok neiroblastomy myshi i ego izmenenie v protsesse rosta i morfologicheskoi differentsirovki kletochnoi populiatsii.

Microelectrophoresis method was used to study the surface charge of murine neuroblastoma cells (clone C1300-N18TG2). It was shown that the surface charge of these cells was determined mainly by anionic groups of the membrane which were distributed with density 0.2 e/nm3 in the layer covering its outer surface. The thickness of this layer was about 10 nm. These groups interacted with Ca ions (binding constant Kca-10-50 l/mol) and were titrated according to pK-3.8. Trypsin, neuraminidase and N-bromosuccinimide (which irreversibly neutralize the carboxylic groups of proteins) decreased the electrophoretic mobility of neuroblastoma cells while tosylchloride (a specific reagent for aminogroups) slightly increased it. The surface charge depended also on the conditions of cultivation of cell population. Morphological cell differentiation induced by removing the serum from the culture medium increased their mobility by about 30%. During the cultivation of cells in a medium with 10 or 50% of serum variations of the their mean electrophoretic mobility value were observed which were opposite-phase to the value of the daily increment of the number of cells. It was assumed that these effects were connected with partial self-synchronization of cell population. It is concluded that the surface charge of the neuroblastoma cells determined by microelectrophoresis method is mainly determined by the carboxylic groups of membrane periphery proteins and gangliosides and the content of these membrane components depends on the stage of cell development.

[Study of the surface properties of spinal ganglion neurons in the rat by the microelectrophoresis technic]. / Issledovanie svoistv poverkhnosti neironov spinal'nykh gangliev krys s ispol'zovaniem metoda mikroélektroforeza.

Surface charges of isolated neurons of rat dorsal root ganglion were studied by the microelectrophoresis. It was shown that the surface potential of these neurons is produced by anion groups which form complexes with calcium ions and a binding constant ranging from 10 to 50 1/mole; they can be titrated by hydrogen ions according to pK = 3.8. Under trypsin treatment the surface loses most of these groups. Tosylchloride (reagent for aminogroups ) slightly increases the surface charge and N- bromsuccinimide (reagent for carboxylic groups) partially neutralizes it. It is suggested that the surface charge of rat dorsal root ganglion neurons measured by the microelectrophoresis is mainly determined by carboxylic groups of periphery proteins. These groups seem to be located in the glycoprotein sheath which covers the outer surface of the membrane. According to our estimates the average distance between these groups is about 2 nm and the thickness of the sheath is about 10 nm.

[Quantitative description of a slowly inactivating barium current through the somatic membrane of mollusk neurons]. / Kolichestvennoe opisanie medlenno inaktiviruiushchegosia barievogo toka cherez somaticheskuiu membranu neironov molliuskov.

The slow-inactivating barium current was recorded under voltage clamp conditions from identified neurons of the snail Helix pomatia. Experimental data were analyzed using the Hodgkin-Huxley equations. The dependence of the steady-state value of the inactivation variable on membrane potential was obtained. Slow-inactivating barium current was found to be proportional to the third power of the activation variable. The time constant of activation is strongly dependent upon the membrane potential.

[Effect of calcium ions on potential-dependent potassium channels in the membrane of the soma of giant mollusc neurons]. / Vliianie ionov kal'tsiia na potentsialozavisimye kalievye kanaly membrany somy gigantskikh neironov molliuskov

The delayed and fast outward currents in the somatic membrane of mollusc giant neurons were studied under voltage-clamp conditions in normal (10 mM) and low-Ca (I mM) saline. At pH 7.2 a tenfold decrease in calcium concentration in the peak conductance vs membrane potential curves for delayed and fast outward currents were shifted along the voltage axis by 10 mV. The shift along voltage axis of the inactivation curve for fast outward current under similar conditions was the same. At pH 9 the shift for a tenfold decrease in calcium concentration was 20 mV. Such an increase in the effect of calcium concentration change at pH 9 is probably due to the increase in the negative charge density in the vicinity of the potassium pathways. The dependence of the rate constants of inactivation alphab and betab for fast outward current upon the membrane potential was studied in solutions with different calcium concentration. The expressions for their calculation were obtained.