Effect of phosphorylation on the functional properties of the sodium channel reconstituted into an artificial membrane

The phosphorylation by protein kinase A of cytoplasmic protein of bovine brain, reconstituted as liposome membrane, is studied. The reconstituted protein imitates the potential-dependent sodium channel. The effect of phosphorylation is shown to depend on the way in which the protein is reconstructed into the artificial membrane. Phosphorylation of channels reconstructed in the open state inhibits the rate of sodium ion flux, while phosphorylation of channels reconstructed in the closed state enhances the activating effect of veratrine and scorpion toxin.A. A. Bogomolets Institute of Physiology, Ukrainian Academy of Sciences, Kiev. A. V. Palladin Institute of Biochemistry, Ukrainian Academy of Sciences, Kiev. Translated from Neirofiziologiya, Vol. 24, No. 2, pp. 192–198, March–April, 1992.     

Antigenic similarity between cytoplasmic tetrodotoxin-sensitive protein and neuronal membrane proteins

Membrane proteins with a molecular weight of 290, 180, and 55 kDa were isolated using immunosorbent attached to sepharose and rabbit antibodies to cytoplasmic tetrodotoxin-sensitive protein from beef brain gray matter. A technique used for research into voltage-dependent sodium channels was applied to reconstruction of these proteins and investigation of toxin-dependent sodium flows through the lipoprotein membrane. Findings are interpreted as evidence of the similarity between cytoplasmic tetrodotoxin-sensitive protein and that of sodium channels at the cell membrane.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev; A. V. Palladin Institute of Biochemistry, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 21, No. 4, pp. 485–489, July–August, 1989.     

Effect of the alkaloid lappaconitine on ionic currents through the somatic membrane ofHelix pomatia neurons

The effect of the alkaloid lappaconitine on passive ion transport through the somatic membrane of identified neurons of the snailHelix pomatia was studied under voltage clamp conditions. In a concentration of 4 mM lappaconitine has a reversible blocking action on the calcium channels of the excitable membrane. To study the effect of the alkaloid on inward sodium currents a solution in which calcium ions were replaced by the equivalent number of magnesium ions was used. Lappaconitine has no appreciable effect on the inward sodium current.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Institute of Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Neirofiziologiya, Vol. 11, No. 5, pp. 469–474, September–October, 1979.     

Integration of soluble tetrodotoxin-sensitive brain proteins with liposomal membranes

Interaction of tetrodotoxin-sensitive proteins of the soluble cytoplasmic fraction of mammalian brain with liposomes was studied. Tetrodotoxin-sensitive proteins were shown to be incorporated in an orderly transmembrane manner into liposomes of a particular chemical composition (phosphatidylcholine-phosphatidylserine-cholesterol, brain phospholipids-cholesterol).A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. A. V. Palladin Institute of Biochemistry, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 16, No. 5, pp. 716–725, September–October, 1984.     

Effects of allapinine on sodium currents in neurons isolated from the rat trigeminal ganglion and cardiomyocytes

The effects were investigated of allapinine, diterpene alkaloid on ionic currents in voltage-clamped trigeminal neurons and cardiomyocytes isolated from rats. Allapinine application was found to exert an inhibitory effect on inward tetrodotoxin-sensitive sodium currents without changing their voltage dependence. Potential differences between the mechanisms of antiarrhythmic action of diterpene alkaloids and standard antiarrhythmic substances are examined.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Institute of Plant Chemistry, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Neirofiziologiya, Vol. 22, No. 2, pp. 201–206, March–April, 1990.     

Monoclonal antibodies to cytoplasmic tetrodotoxin-sensitive brain protein. Effects of veratrine on binding between antibodies and neuroblastoma cells

The effects were studied of neurotoxins, which modulate the activity of voltagedependent sodium channels, on binding between neuroblastoma cells and monoclonal antibodies to cytoplasmic tetrodotoxin-sensitive protein displaying the properties of tetrodotoxin-sensitive sodium channles when incorporated into the liposomes. Binding between antibodies and the monolayer of viable (unfixed) cells recorded by immunoenzyme testing was found to break down in the presence of veratrine (veratridine). It is postulated that the antibodies obtained bind with an antigenic determinant located at or near the veratrine binding site.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 20, No. 6, pp. 794–800, November–December, 1988.     

Common features of antigenic determinants present on mammalian nerve cell membrane structures and in cytoplasmic tetrodotoxin-sensitive proteins

Possible antigenic features common to nerve cell membrane structures and cytoplasmic tetrodotoxin-sensitive proteins were investigated by means of an immobilized immunoenzyme test. It was found that antiserum obtained by immunizing rabbits with a purified preparation of cytoplasmic tetrodotoxin-sensitive proteins can react with antigenic determinants present on the membrane fraction of bovine brain cells, on rat synaptosomes and on cells of a clonal line of mouse neuroblastoma. It was shown by means of an inhibition assay test that antibodies of the same specificity contribute to the observed response. Findings would indicate the presence of antigenic determinants common to nerve cell membrane structures and cytoplasmic tetrodotoxin-sensitive proteins. This is consistent with the hypothesis that cytoplasmic tetrodotoxin-sensitive proteins have certain features in common with membrane sodium channels.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. A. V. Palladin Institute of Biochemistry, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 19, No. 3, pp. 369–372, May–June, 1987.     

Inhibitory and excitatory processes in thalamic motor nuclei neurons in the normal nigrostriatal dopaminergic system and following injury to it produced by N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine

Excitatory and inhibitory processes in neurons of the thalamic anteroventral and ventrolateral (VA–VL) motor nuclei were investigated in two sets of experiments on cats anesthetized with Ketalar and immobilized by myorelaxant during the course of stimulation of the red nucleus region and following chronic administration of N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP, 5 mg/kg i.m. over a 5-day period): It was found 48 h after the last MPTP injection that up to 48% neurons belonging to the substantia nigra pars compacta had been destroyed and that dopamine level had declined to 30% of that found in intact animals. In cats injected with MPTP inhibitory processes declined significantly in both duration and efficacy in VA–VL relay and non-relay neurons, while latency of orthodromic excitatory response to red nucleus stimulation declined. It is suggested that attenuation of dopamine-modulated GABA-ergic nigrothalamic influences underlies the low level of inhibition occurring.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Institute of Endocrinology and Metabolism, Ukrainian Ministry of Public Health, Kiev. Institute of Organic Chemistry, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 21, No. 5, pp. 620–629, September–October, 1989.     

Murine neuroblastoma cells absorb anti-cytoplasmic tetrodotoxin-sensitive protein antibodies

The properties were investigated of polyclonal antibodies obtained by immunizing with a fraction of cytoplasmic glycoproteins forming sodium channels in liposomes. It was shown that these antibodies can be absorbed by intact murine neuroblastoma cells. Graphs plotting intensity of absorption against numbers of absorbant cells follow a characteristic course dependent on life of the cells in culture and serum concentration in the culture medium.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 20, No. 1, pp. 98–105, January–February, 1988.     

Inactivation of outward potassium current dependent on extracellular Ca+

A. A. Bogomolets Institute of Physiology and Institute for Theoretical Physics, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 20, No. 5, pp. 602–610, September–October, 1988.     

Changes in the ionic mechanisms of the electrical excitability of rat sensory neuronal somatic membrane during ontogenesis. Distribution of ionic channels carrying inward currents

The distribution of different types of ionic channels carrying inward currents was investigated in the somatic membranes of spinal ganglion neurons in rats belonging to three different age groups: at 5–9 days, 45 days, and 3 months. A decrease was found in the number of neuronal membranes operating all four types of inward current channels simultaneously: "fast" (tetrodotoxin-sensitive), "slow" (tetrodotoxin-resistant) sodium currents and low- and high-threshold calcium currents. There were 14.5% of such neurons in the first age group, 5% in the second, and 1% on the third. It was found that this change was related to the disappearance of "slow" (tetrodotoxin-resistant) sodium and high-threshold calcium channels from the membrane. The number of neuronal somatic membranes with only two types of inward current channels ("fast" sodium and high-threshold calcium channels) increased proportionately.A. A. Bogomolets Institute of Technology, Academy of Sciences of the Ukrainian SSR, Kiev Translated from Neirofiziologiya, Vol. 18, No. 6, pp. 813–820, November–December, 1986.     

Modification to the Hodgkin-Huxley equation as applied to the somatic membrane of mollusk giant neurons

A modified system of Hodgkin-Huxley equations was used to describe transmembrane ionic currents during fixed changes of membrane potential and generation of action potentials in the soma of mollusk giant neurons. The effect of the axon was disregarded. The results of theoretical calculations are in satisfactory agreement with experimental results.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 5, No. 3, pp. 315–322, May–June, 1973.     

Benzodiazepine receptors in the mammalian central nervous system

A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 20, No. 2, pp. 269–279, March–April, 1988.     

Action of neurotoxin from the sea anemoneHomostichanthus duerdemi on inward sodium current in mammalian neurons

The action of purified toxin from the sea anemoneHomostichanthus duerdemi (HTX-1) on the inward sodium current was studied in experiments on isolated neurons from rat spinal ganglia and neuroblastoma cells of clone N-18F1, by an intracellular perfusion and voltage clamp method. HTX-1 was found to delay inactivation of the tetrodotoxin-(TTX-)sensitive inward sodium current and to make it incomplete, but virtually without affecting its activation. The relationship between the fraction of sodium channels modified by the toxin and the HTX-1 concentration is described by a Langmuir isotherm with association constant of (1.1 ± 0.1)·10^–7 M (holding potential –100 mV). Under the influence of the toxin the peak inward sodium current was increased by about 80%. Binding of HTX-1 with TTX-sensitive sodium channels is distinguished by strong potential-dependence: at a holding membrane potential of 0 mV the binding constant was an order of magnitude less than at a potential of –100 mV. In the case of brief action of HTX-1 on the nerve cell membrane (under 5 min) the effect of the toxin was completely reversible, but if the time of action of HTX-1 exceeded 30 min, subsequent washing with normal solution for 90 min did not abolish the effect completely.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Pacific Institute of Bioorganic Chemistry, Far Eastern Scientific Center, Academy of Sciences of the USSR, Vladivostok. Translated from Neirofiziologiya, Vol. 14, No. 4, pp. 402–409, July–August, 1982.     

Changes in "calcium" action potentials in neurons of the rat spinal ganglia during replacement of divalent cations in the extracellular medium

Single neurons of rat spinal ganglia were investigated in adult rats using a voltage clamping technique and intracellular microelectrodes. Removing sodium ions from the extracellular medium and adding tetraethylammonium to it enabled the calcium component of action potentials to be recorded. It was found that progressive selective suppression of this component takes place during extracellular recording, indicating a decrease in calcium conductivity, while sodium and potassium levels are maintained. It is suggested that this disturbance is caused by excessive influx of calcium, strontium, or barium ions into the cell. The calcium component of action potentials was also found to depend on stimulation rate; this dependence differed where calcium ions were replaced by strontium or barium ions. A possible connection between this effect and the process of voltage-dependent inactivation of calcium channels is discussed.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 18, No. 2, pp. 202–207, March–April, 1986.     

Action of thiamine on auditory evoked potentials in the guinea pig

A technique is proposed for quantifying the effects of physiologically active substances at the periphery of the auditory analyzer. It was found that applying 1×10^–11 to 1×10^–3 M thiamine to the membrane of guinea pig cochlear round window (fenestra rotunda) produces a rise in the amplitude and a reduction in the latency of the N₁ and N₂ components of auditory nerve action potentials, waves I and II of brainstem auditory evoked potentials occurring in response to an acoustic stimulus. It is suggested that this effect is produced by facilitated synaptic transmission at synapses between hair cells and spiral ganglia neurons under the action of thiamine penetrating into the cochlea.A. V. Palladin Institute of Biochemistry, Academy of Sciences of the Ukrainian SSR, Kiev. A. I. Kolomiichenko Research Institute of Otolaryngology, Ministry of Public Health of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 18, No. 5, pp. 654–660, September–October, 1986.     

Changes in the ionic mechanisms of electrical excitability in the somatic membrane of rat dorsal root ganglion neurons during ontogenesis. Correlations between inward current densities

Correlations between densities of various types of inward currents in the somatic membrane of dorsal root ganglion neurons were studied in three different rat age groups: 5–9 days, 45 days, and 90 days. A linear relationship was found in neurons with "slow" tetrodotoxin-sensitive sodium current between the densities of high-threshold calcium current and "slow" sodium current (Bravias-Pearson's correlation coefficient: r=0.84 and 0.70 for n₁=16 and n₂=28, respectively). No such correlation was observed in neurons with low-threshold calcium inward current. Cells with only two types of channel — "fast" sodium and high-threshold calcium — present in their somatic membrane manifested an inverse correlation (r=–0.48, where n₄=95) between the densities of transmembrane currents passing through these channels. No inverse relationship was observed in the density of "fast" sodium and high-threshold calcium currents in neurons with tetradotoxinresistant "slow" sodium and/or low threshold calcium channels.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 18, No. 6, pp. 820–827, November–December, 1986.     

Rubrocaudate projections in the cat

Small numbers of neurons projecting to the caudate nucleus were found in the cat red nucleus using horseradish peroxidase retrograde axonal transport techniques. Rubrocaudate neurons were found in both the parvo- and magnocellular sections of the red nucleus. Organization of reciprocal connections between the red nucleus and the striopallidal system is discussed.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 20, No. 1, pp. 28–32, January–February, 1988.     

Interaction between sea anemone toxin BgTX8 and ionic channels of neurons isolated from mammals

The action of the toxin BgTX₈ separated from the sea actiniaBunodosoma granolifera on transient tetrodotoxin-sensitive sodium and outward potassium currents of units isolated from rat sensory ganglia was investigated using techniques of voltage clamping at the membrane and intracellular perfusion. It was found that BgTX₈ decelerates the inactivation kinetics but has little effect on activation kinetics of sodium current. At the same time, a 5–10% increase in the amplitude of inward current was often observed at holding potentials of about –100 to –120 mV at the membrane. The dissociation constant of the receptor-toxin equals 4×10^–6 M and is adequately described by Langmuir's isotherm. It was also established that intracellular perfusion of neurons with anemone toxin-containing solution leads to a reduction in the amplitude of sodium current and decelerates its inactivation process. Suppression of outward potassium current was also noted.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Institute of Brain Research, Academy of Sciences, Havana, Cuba. Translated from Neirofiziologiya, Vol. 20, No. 1, pp. 32–37, January–February, 1988.     

Sodium and calcium channels in the somatic membrane of artificially differentiated neuroblastoma cells

Using an intracellular dialysis technique a study was made on calcium and sodium inward currents at the neuroblastoma somatic cell membrane in suspension and during the course of artificial morphological differentiation produced by raising the pH of the culture medium to 8.0–8.2. The density of sodium currents in the somata of cells cultured in the suspension averaged 7.3±0.8 µA/µF, while this value varied from 37±5.2 to 54.7±3.6 µA/µF at various stages of culture. These values equalled 1.4±0.2 and 1.1±0.2 to 2.8±0.4 µA/µF in the case of calcium currents. Reciprocal changes were produced in the density of sodium and calcium channels by altering the culture medium.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 18, No. 2, pp. 207–214, March–April, 1986.