Nerve Ending

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Andrey L. Zefirov - One of the best experts on this subject based on the ideXlab platform.

  • Role of Ryanodine Receptors in the Effects of Hydrogen Sulfide on Transmitter Release from the Frog Motor Nerve Ending
    Bulletin of Experimental Biology and Medicine, 2013
    Co-Authors: E. V. Gerasimova, O. V. Yakovleva, Andrey L. Zefirov, Guzel F. Sitdikova
    Abstract:

    We studied the role of ryanodine receptors in the effects of hydrogen sulfide on transmitter release from frog motor Nerve Ending. Sodium hydrosulfide (300 μM), a donor of hydrogen sulfide, reversibly increased the frequency of miniature endplate current without changes in its amplitude–time parameters. These effects were associated with reversible increase in endplate current amplitude, which was abolished by activation of ryanodine receptors of intracellular Ca^2+ stores with caffeine (3 mM) and ryanodine (0.5 μM). Under conditions of ryanodine receptors blockade with ryanodine (10 μM), sodium hydrosulfide had no effect on induced transmitter release, but its effects remained unchanged during ryanodine receptors blockade with dantrolene (25 μM). We concluded that an enhanced acetylcholine release induced by hydrogen sulfide is related to an increase of intracellular Ca^2+ concentration due to activation of ryanodine receptors for intracellular Ca^2+-pool.

  • Fatty acids modulate transmitter release and functioning of potassium channels in motor Nerve Endings
    Neurochemical Journal, 2007
    Co-Authors: O. V. Yakovleva, Guzel F. Sitdikova, Elena Gerasimova, Andrey L. Zefirov
    Abstract:

    An extracellular microelectrode applied to the neuromuscular junction of the frog sternocutaneus muscle was used to study effects of saturated (myristic and arachidic) and unsaturated (arachidonic and oleic) fatty acids on transmitter release and potassium currents in a Nerve Ending. All these fatty acids decreased evoked transmitter release. Unsaturated fatty acids decreased the amplitude of voltage-dependent and calciumactivated potassium currents in a Nerve Ending, whereas saturated acids were ineffective. Rhythmic stimulation applied in the presence of arachidonic and oleic acids induced more pronounced facilitation of the transmitter release, whereas the effects of myristic and arachidic acids did not differ from control values. Deoxycholate was not able to reproduce the effects of fatty acids on the transmitter release and potassium current in a Nerve Ending. It was concluded that fatty acids can modulate transmitter release and synaptic excitatory transmission; these effects can have a significant influence on molecular mechanisms of exocytosis of synaptic vesicles and electrogenesis in a motor Nerve Ending. The latter effect is characteristic of unsaturated (arachidonic and oleic) acids, whereas the former effect does not depend on the degree of unsaturation at all.

  • The intracellular calcium and mechanisms of endocytosis of synaptic vesicles at the frog Nerve Ending
    Tsitologiia, 2006
    Co-Authors: Andrey L. Zefirov, Alexey M. Petrov
    Abstract:

    In the experiments on frog motor Nerve Endings of cutaneous pectoris muscle, made by extracellular recording of synaptic signals, it has been shown that the increase in intracellular calcium ion concentration in the Nerve Ending (by enhance of extracellular potassium ion concentration, or by addition of caffeine) leads to an increase in the miniature end-plate potential frequency, which is preserved over the whole period (about 10 min) of action of these substrates. The rhythmic stimulation of motor Nerve (20 or 100 imp/s) quickly leads to a decrease in the end plate potentials amplitude. It has been shown by fluorescent microscopy with the use of endocytotic marker FM 1-43 that in the course of a short time exposition (5 min) in a high potassium solution (40 mM) or caffeine (5 mM), light spots appeared in the Nerve Ending. This shows that synaptic vesicles undergo intensive processes of endocytosis. During a longer exposition (30 min) no light spots were revealed, whereas the Nerve Ending width increased. This data allowed to propose that the process of endocytosis was blocked. In the presence of even lower concentrations of potassium ions and caffeine, and during a long rhythmic stimulation (20 or 100 imp/s) no blocking of endocytosis was revealed. It is concluded that high concentrations of intracellular calcium in the frog motor Nerve Ending leads to a reversible block of endocytosis, while exocytosis in synaptic vesicles is proceeding.

  • the effects of l and d stereoisomers on the transmitter secretion and ionic currents in the motor Nerve Ending
    Doklady Biological Sciences, 2003
    Co-Authors: Guzel F. Sitdikova, Andrey L. Zefirov, A V Yakovlev, O V Arkhipova
    Abstract:

    In this work, we studied the effect of L - and D -stereoisomers of arginine on ionic currents in the motor Nerve Ending and induced transmitter secretion in the neuromuscular synapse of the frog. The experiments were performed with the neuromuscular junction of cutaneous pectoris muscle of the marsh frog in autumn and winter. The preparations were constantly perfused with the Ringer solution for poikilothermal animals. To eliminate the action potentials and contractions of muscular fibers, we used the Ringer solution with a decreased Ca 2+ concentration, containing 118 mM NaCl, 2.5 mM KCl, 0.3‐0.4 mM CaCl 2 , 2.0‐4.0 mM MgCl 2 , and 2.4 mM NaHCO 3 (pH 7.4‐7.6 at 20ie ). For extracellular lead of synaptic signals, we used glass microelectrodes that were applied on the proximal part of the Nerve Ending (30 to 50 μ m from the last myelinated axonal segment). This process was controlled visually, using a polarizationinterference microscope (resolution, 400 〈 ). The motor Nerve was stimulated by rectangle electric pulses with overthreshold amplitude (duration, 0.3‐0.4 ms; frequency, 0.5‐1 pps). We recorded the three-phase response (+ ‐ +) of Nerve Ending to each stimulus, which reflected the ionic currents forming the action potential, and the subsequent endplate current (EC) [2]. The first positive phase is a passive (capacitive) current, generated by the entering action potential; the second, negative phase is an entering sodium current; and the third positive phase is an outgoing potassium current across voltage-dependent and Calcium-activated potassium channels [2]. Because our experiments were performed at low extracellular concentration of Ca 2+ , it can be accepted that Calcium-activated potassium current predominantly reflects the voltage-dependent potassium current. The analysis, averaging, and accumulation of recorded signals were performed using a Pentium II PC. We determined the amplitude and duration of each phase of Nerve-Ending response relative the baseline value and the EC amplitude. The quantum content of EC ( m ) was determined by counting the zero responses according to the equation: m = , where

  • analysis of living motor Nerve Ending of a frog by endocytotic fluorescent marker fm 1 43
    Tsitologiia, 2003
    Co-Authors: Andrey L. Zefirov, P N Grigorev, A M Petrov, M G Minlebaev, Guzel F. Sitdikova
    Abstract:

    In our experiments on motor Nerve Endings of the frog cutaneous pectoris muscle, using fluorescent marker FM 1-43, the intensity and topography of endocytosis were investigated after the initiation of massive exocytosis of synaptic vesicles by increasing the extracellular potassium concentration. Using FM 1-43, fluorescent spots were shown to appear, looking as accumulations of synaptic vesicles in the active zone region. The forms and sizes of luminous spots and the distances between them were analysed. Considerable variations in brightness and total areas of fluorescent spots per a length unit in different regions of the Nerve Ending were revealed in addition to a proximal-distal gradient of these parameters along the Nerve terminal. Peculiarities of topography and intensities of luminescence in the most terminal regions of the Nerve Ending are described. The obtained data are discussed in terms of the exo- and endocytosis cycle of synaptic vesicles in the active zone region, and from the point of view of the plasticity of the motor Nerve Ending and active zones. The factors involved in the transmitter release nonuniformity are analysed.

Sitdikova G. - One of the best experts on this subject based on the ideXlab platform.

  • Role of ryanodine receptors in the effects of hydrogen sulfide on transmitter release from the frog motor Nerve Ending
    2020
    Co-Authors: Gerasimova E., Yakovleva O., Zefirov A., Sitdikova G.
    Abstract:

    We studied the role of ryanodine receptors in the effects of hydrogen sulfide on transmitter release from frog motor Nerve Ending. Sodium hydrosulfide (300 μM), a donor of hydrogen sulfide, reversibly increased the frequency of miniature endplate current without changes in its amplitude-time parameters. These effects were associated with reversible increase in endplate current amplitude, which was abolished by activation of ryanodine receptors of intracellular Ca2+ stores with caffeine (3 mM) and ryanodine (0.5 μM). Under conditions of ryanodine receptors blockade with ryanodine (10 μM), sodium hydrosulfide had no effect on induced transmitter release, but its effects remained unchanged during ryanodine receptors blockade with dantrolene (25 μM). We concluded that an enhanced acetylcholine release induced by hydrogen sulfide is related to an increase of intracellular Ca 2+ concentration due to activation of ryanodine receptors for intracellular Ca2+-pool. © 2013 Springer Science+Business Media New York

  • Analysis of Exo- and endocytosis in the mouse Nerve Ending in experimental diabetes mellitus
    2020
    Co-Authors: Yakovleva O., Zefirov A., Zaharov A., Sitdikova G.
    Abstract:

    Diabetes mellitus (DM) is a systemic disease characterized by changes in many organs and tissues, including the motor system. The aim of this work was a study of the processes of exo- and endocytosis in the motor Nerve Ending of mouse diaphragm during high-frequency activity in experimental alloxan model of DM. Endplate potentials (EPPs) was recorded using intracellular microelectrodes during single and high-frequency (50 Hz, 1 min) stimulation. In mice with experimental DM the amplitude-temporary parameters of EPPs did not differ from the control; however, an increase in the EPPs depression and a slower recovery was observed during high frequency stimulation. Using an endocytosis dye FM 1-43, it was shown that in animals with experimental DM the intensity of fluorescence of Nerve terminals loaded by high-frequency stimulation was higher than in control. This effect was prevented by an inhibitor of slow dynamin-mediated endocytosis - 1-azakenpaullone (2 μM). In addition, the bleaching of pre-loaded Nerve terminals during high-frequency stimulation was slower in animals with DM. The obtained results suggest that in experimental DM the recycling of synaptic vesicles via the long path becomes more pronounced and the mechanisms of the vesicular transport are impaired. This hypothesis was confirmed by methods of mathematical modeling

  • Fatty acids modulate transmitter release and functioning of potassium channels in motor Nerve Endings
    2020
    Co-Authors: Yakovleva O., Gerasimova E., Sitdikova G., Zefirov A.
    Abstract:

    An extracellular microelectrode applied to the neuromuscular junction of the frog sternocutaneus muscle was used to study effects of saturated (myristic and arachidic) and unsaturated (arachidonic and oleic) fatty acids on transmitter release and potassium currents in a Nerve Ending. All these fatty acids decreased evoked transmitter release. Unsaturated fatty acids decreased the amplitude of voltage-dependent and calciumactivated potassium currents in a Nerve Ending, whereas saturated acids were ineffective. Rhythmic stimulation applied in the presence of arachidonic and oleic acids induced more pronounced facilitation of the transmitter release, whereas the effects of myristic and arachidic acids did not differ from control values. Deoxycholate was not able to reproduce the effects of fatty acids on the transmitter release and potassium current in a Nerve Ending. It was concluded that fatty acids can modulate transmitter release and synaptic excitatory transmission; these effects can have a significant influence on molecular mechanisms of exocytosis of synaptic vesicles and electrogenesis in a motor Nerve Ending. The latter effect is characteristic of unsaturated (arachidonic and oleic) acids, whereas the former effect does not depend on the degree of unsaturation at all. © Pleiades Publishing, Ltd. 2007

  • The presynaptic effects of arachidonic acid and prostaglandin E2 at the frog neuromuscular junction
    2020
    Co-Authors: Arkhipova O., Sitdikova G., Grishin S., Zefirov A.
    Abstract:

    Arachidonic acid and prostaglandin E2 decreased the frequency of miniature endplate potentials with producing any changes in the their amplitude-time parameters. Arachidonic acid and prostaglandin E2 decreased the quantum composition of endplate currents and the amplitude of the third phase of the Nerve Ending response, which reflects currents though potential-dependent K+ channels. A perineural method was used to demonstrate that arachidonic acid and prostaglandin E2 suppressed the Nerve Ending Ca2+ current. The cyclooxygenase blocker indomethacin increased neurotransmitter secretion and decreased the third phase of the Nerve Ending response. The effects of arachidonic acid and prostaglandin E2 on evoked neurotransmitter release were not seen in the presence of indomethacin, while the third phase of the response continued to show a reduction. It is suggested that prostaglandin E2 mediates the effects of arachidonic acid on spontaneous and evoked neurotransmitter secretion, Ca2+ currents, and Ca2+-dependent K+ currents. In addition, arachidonic acid and prostaglandin E2 had their own effects on potential-dependent K+ currents in Nerve Endings. © 2006 Springer Science+Business Media, Inc

  • Effects of hydrogen sulfide on the processes of exo- and endocytosis of synaptic vesicles in mouse motor Nerve Endings
    2020
    Co-Authors: Mitrukhina O., Yakovlev A., Sitdikova G.
    Abstract:

    The effects of sodium hydrosulfide(NaHS),the donor of hydrogen sulfide(H2S),on the exo-endocytosis cycle of the synaptic vesicles in the motor Nerve Ending of mouse diaphragm were explored using intracellular microelectrode technique and fluorescent microscopy. NaHS increased the frequency of miniature end-plate potentials(MEPPs) without changing its amplitude-time parameters and the amplitude of the postsynaptic responses undersingle stimulus condition(0.3 Hz),giving evidence on enhancing synaptic vesicle exocytosis. During high-frequency stimulation(50 Hz) NaHS induced more significant decline of neurotransmitter secretion,which can be due to the lower rate of synaptic vesicle mobilization from the recycling pool to the exocytic cites. NaHS also decreased the uptake of the fluorescent endocytic dye FM 1-43, which indicates the reduced endocytosis of the synaptic vesicles. Thus,the donor of H2S increased exocytosis and decreased the processes of the synaptic vesicles' endocytosis and mobilization in the mouse motor Nerve Ending

Guzel F. Sitdikova - One of the best experts on this subject based on the ideXlab platform.

  • Analysis of exo- and endocytosis in the mouse Nerve Ending in experimental diabetes mellitus
    Biochemistry (Moscow) Supplement Series A: Membrane and Cell Biology, 2017
    Co-Authors: O. V. Yakovleva, A L Zefirov, A. V. Zakharov, Guzel F. Sitdikova
    Abstract:

    Diabetes mellitus (DM) is a systemic disease characterized by changes in many organs and tissues, including the motor system. The processes of exo- and endocytosis in the motor Nerve Ending of the mouse diaphragm muscle during high-frequency activity in experimental alloxan model of DM were studied. Endplate potentials (EPPs) were recorded using intracellular microelectrodes during single and high-frequency (50 Hz, 1 min) stimulation. In mice with the experimental DM, the amplitude-time parameters of EPPs did not differ from those of the control; however, an increase in EPPs depression and a slower recovery were observed during high-frequency stimulation. Using an endocytosis marker FM 1-43, it was shown that in animals with experimental DM fluorescence intensity of the Nerve terminals loaded with the dye by high-frequency stimulation increased that was prevented by 1-azakenpaullone (2 μM), an inhibitor of slow dynamin-1-mediated endocytosis. In addition, in the model animals, the destaining of the pre-loaded Nerve terminals during high-frequency (50 Hz) stimulation slowed down. The obtained data indicate that in the experimental first type DM recycling of synaptic vesicles via long path becomes more pronounced and the mechanisms of the vesicular transport are impaired, which was confirmed by methods of mathematical modeling.

  • Role of Ryanodine Receptors in the Effects of Hydrogen Sulfide on Transmitter Release from the Frog Motor Nerve Ending
    Bulletin of Experimental Biology and Medicine, 2013
    Co-Authors: E. V. Gerasimova, O. V. Yakovleva, Andrey L. Zefirov, Guzel F. Sitdikova
    Abstract:

    We studied the role of ryanodine receptors in the effects of hydrogen sulfide on transmitter release from frog motor Nerve Ending. Sodium hydrosulfide (300 μM), a donor of hydrogen sulfide, reversibly increased the frequency of miniature endplate current without changes in its amplitude–time parameters. These effects were associated with reversible increase in endplate current amplitude, which was abolished by activation of ryanodine receptors of intracellular Ca^2+ stores with caffeine (3 mM) and ryanodine (0.5 μM). Under conditions of ryanodine receptors blockade with ryanodine (10 μM), sodium hydrosulfide had no effect on induced transmitter release, but its effects remained unchanged during ryanodine receptors blockade with dantrolene (25 μM). We concluded that an enhanced acetylcholine release induced by hydrogen sulfide is related to an increase of intracellular Ca^2+ concentration due to activation of ryanodine receptors for intracellular Ca^2+-pool.

  • Fatty acids modulate transmitter release and functioning of potassium channels in motor Nerve Endings
    Neurochemical Journal, 2007
    Co-Authors: O. V. Yakovleva, Guzel F. Sitdikova, Elena Gerasimova, Andrey L. Zefirov
    Abstract:

    An extracellular microelectrode applied to the neuromuscular junction of the frog sternocutaneus muscle was used to study effects of saturated (myristic and arachidic) and unsaturated (arachidonic and oleic) fatty acids on transmitter release and potassium currents in a Nerve Ending. All these fatty acids decreased evoked transmitter release. Unsaturated fatty acids decreased the amplitude of voltage-dependent and calciumactivated potassium currents in a Nerve Ending, whereas saturated acids were ineffective. Rhythmic stimulation applied in the presence of arachidonic and oleic acids induced more pronounced facilitation of the transmitter release, whereas the effects of myristic and arachidic acids did not differ from control values. Deoxycholate was not able to reproduce the effects of fatty acids on the transmitter release and potassium current in a Nerve Ending. It was concluded that fatty acids can modulate transmitter release and synaptic excitatory transmission; these effects can have a significant influence on molecular mechanisms of exocytosis of synaptic vesicles and electrogenesis in a motor Nerve Ending. The latter effect is characteristic of unsaturated (arachidonic and oleic) acids, whereas the former effect does not depend on the degree of unsaturation at all.

  • the effects of l and d stereoisomers on the transmitter secretion and ionic currents in the motor Nerve Ending
    Doklady Biological Sciences, 2003
    Co-Authors: Guzel F. Sitdikova, Andrey L. Zefirov, A V Yakovlev, O V Arkhipova
    Abstract:

    In this work, we studied the effect of L - and D -stereoisomers of arginine on ionic currents in the motor Nerve Ending and induced transmitter secretion in the neuromuscular synapse of the frog. The experiments were performed with the neuromuscular junction of cutaneous pectoris muscle of the marsh frog in autumn and winter. The preparations were constantly perfused with the Ringer solution for poikilothermal animals. To eliminate the action potentials and contractions of muscular fibers, we used the Ringer solution with a decreased Ca 2+ concentration, containing 118 mM NaCl, 2.5 mM KCl, 0.3‐0.4 mM CaCl 2 , 2.0‐4.0 mM MgCl 2 , and 2.4 mM NaHCO 3 (pH 7.4‐7.6 at 20ie ). For extracellular lead of synaptic signals, we used glass microelectrodes that were applied on the proximal part of the Nerve Ending (30 to 50 μ m from the last myelinated axonal segment). This process was controlled visually, using a polarizationinterference microscope (resolution, 400 〈 ). The motor Nerve was stimulated by rectangle electric pulses with overthreshold amplitude (duration, 0.3‐0.4 ms; frequency, 0.5‐1 pps). We recorded the three-phase response (+ ‐ +) of Nerve Ending to each stimulus, which reflected the ionic currents forming the action potential, and the subsequent endplate current (EC) [2]. The first positive phase is a passive (capacitive) current, generated by the entering action potential; the second, negative phase is an entering sodium current; and the third positive phase is an outgoing potassium current across voltage-dependent and Calcium-activated potassium channels [2]. Because our experiments were performed at low extracellular concentration of Ca 2+ , it can be accepted that Calcium-activated potassium current predominantly reflects the voltage-dependent potassium current. The analysis, averaging, and accumulation of recorded signals were performed using a Pentium II PC. We determined the amplitude and duration of each phase of Nerve-Ending response relative the baseline value and the EC amplitude. The quantum content of EC ( m ) was determined by counting the zero responses according to the equation: m = , where

  • analysis of living motor Nerve Ending of a frog by endocytotic fluorescent marker fm 1 43
    Tsitologiia, 2003
    Co-Authors: Andrey L. Zefirov, P N Grigorev, A M Petrov, M G Minlebaev, Guzel F. Sitdikova
    Abstract:

    In our experiments on motor Nerve Endings of the frog cutaneous pectoris muscle, using fluorescent marker FM 1-43, the intensity and topography of endocytosis were investigated after the initiation of massive exocytosis of synaptic vesicles by increasing the extracellular potassium concentration. Using FM 1-43, fluorescent spots were shown to appear, looking as accumulations of synaptic vesicles in the active zone region. The forms and sizes of luminous spots and the distances between them were analysed. Considerable variations in brightness and total areas of fluorescent spots per a length unit in different regions of the Nerve Ending were revealed in addition to a proximal-distal gradient of these parameters along the Nerve terminal. Peculiarities of topography and intensities of luminescence in the most terminal regions of the Nerve Ending are described. The obtained data are discussed in terms of the exo- and endocytosis cycle of synaptic vesicles in the active zone region, and from the point of view of the plasticity of the motor Nerve Ending and active zones. The factors involved in the transmitter release nonuniformity are analysed.

Ian A Silver - One of the best experts on this subject based on the ideXlab platform.

Maria Erecinska - One of the best experts on this subject based on the ideXlab platform.

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