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A. F. Korystova - One of the best experts on this subject based on the ideXlab platform.

  • The regulation of L-type Ca2+ currents in rat cardiac myocytes.
    Membrane & cell biology, 2000
    Co-Authors: A. F. Korystova, A. S. Grichenko
    Abstract:

    The regulation of L-type Ca2+ current in isolated rat cardiac cells was studied using the Perforated Patch-Clamp technique. A dual effect of the cAMP-dependent phosphorylation activator, isoproterenol, at different holding potentials (V(h)) was shown. The currents increased at V(h) = -50 mV and decreased at V(h) = -30 mV. A dihydropyridine agonist, BAY K 8644, and isoproterenol had an additive effect on the activation of Ca2+ channels at holding potentials close to the resting potential. The additivity was disturbed at more positive V(h). The activating effect of BAY K 8644 did not virtually change in the presence of a protein kinase blocker, H8, and a phosphatase activator, acetylcholine. The results were interpreted within the framework of a two-site phosphorylation model with two independent pathways of Ca2+ current regulation.

  • Effect of Isoproterenol on the L-type Ca^2+ Current in Cardiac Cells from Rats and Hybernating Ground Squirrels
    Bioscience Reports, 1999
    Co-Authors: Yu. M. Kokoz, A. F. Korystova, A. S. Grichenko, D. A. Lankina, N. I. Markevich
    Abstract:

    The Perforated Patch Clamp method was used to study the effect of the agonist of beta-adrenoreceptors isoproterenol on L-type Ca^2+ current in cardiocytes of rats and ground squirrels in two states: active and hibernating. It is shown that isoproterenol exerts a dual effect on Ca^2+ currents of rats and ground squirrels in the active state: at V _h = −50 mV, the current increases, whereas at V _h = −30 mV, it decreases. In hibernating ground squirrels, the dual effect of isoproterenol is not observed: isoproterenol increases Ca^2+ current at any V _h values. The hypothesis is put forward that, during the entrance of ground squirrels into hibernation, the phosphorylation of one of the sites (not cAMP-dependent) of L-type Ca^2+ channels is blocked.

  • Effect of isoproterenol on the L-type Ca2+ current in cardiac cells from rats and hybernating ground squirrels.
    Bioscience reports, 1999
    Co-Authors: Yu. M. Kokoz, A. S. Grichenko, A. F. Korystova
    Abstract:

    The Perforated Patch Clamp method was used to study the effect of the agonist of beta-adrenoreceptors isoproterenol on L-type Ca2+ current in cardiocytes of rats and ground squirrels in two states: active and hibernating. It is shown that isoproterenol exerts a dual effect on Ca2+ currents of rats and ground squirrels in the active state: at Vh = −50 mV, the current increases, whereas at Vh = −30 mV, it decreases. In hibernating ground squirrels, the dual effect of isoproterenol is not observed: isoproterenol increases Ca2+ current at any Vh values. The hypothesis is put forward that, during the entrance of ground squirrels into hibernation, the phosphorylation of one of the sites (not cAMP-dependent) of L-type Ca2+ channels is blocked.

  • Potential-dependent Ca2+ currents in isolated heart cells of hibernators.
    Biochemistry and molecular biology international, 1994
    Co-Authors: Alexey E. Alekseev, A. F. Korystova
    Abstract:

    Using the Perforated Patch-Clamp technique, it has been shown that the potential-dependent Ca2+ current in cardiac myocytes of hibernators is not completely inhibited during hibernation. The residual Ca2+ current is classed as L-type Ca2+ current which is regulated by agonists and antagonists of Ca2+ channels. The effect of nifedipine, D600, isoproterenol and forskolin has been examined. It was found that isoproterenol affects the affinity of Ca2+ channels for the D600 blocker.

Norio Akaike - One of the best experts on this subject based on the ideXlab platform.

  • Excitatory effects of ATP on rat dorsomedial hypothalamic neurons.
    Brain Research, 2004
    Co-Authors: Nozomu Matsumoto, Masaru Sorimachi, Norio Akaike
    Abstract:

    Abstract We investigated P2X purinoceptors in rat dorsomedial hypothalamic (DMH) neurons using nystatin-Perforated Patch-Clamp recordings and fura-2 microfluorometry. Adenosine triphosphate (ATP) concentration-dependently evoked an inward current and increased cytosolic Ca 2+ ([Ca] i ). The rise in [Ca] i was dependent on external Ca 2+ and Na + , was blocked by Ca 2+ channel antagonists and had pharmacological properties consistent with P2X2 receptors. These results suggest that P2X receptor-mediated depolarization activates voltage-gated Ca 2+ channels, resulting in an increase in [Ca] i .

  • Kinetic characteristics of thrombin receptor-mediated responses in rat megakaryocytes
    European Journal of Pharmacology, 1997
    Co-Authors: Chikako Uneyama, Hisayuki Uneyama, Kuniaki Narisawa, Michihito Takahashi, Norio Akaike
    Abstract:

    Kinetic characteristics of thrombin receptor-mediated responses on rat megakaryocytes were examined by the use of the Perforated Patch Clamp combined with the rapid drug exchange system termed the 'Y-tube method'. The application of thrombin evoked repetitive Ca(2+)-activated K+ current (IKCa) in a concentration-dependent manner. The characteristic features for thrombin-induced response compared with purinoceptor-induced response were the long latency, long washout time and fast desensitization. The similar IKCa as thrombin was induced by trypsin. Thrombin- and trypsin-induced IKCa were both inhibited by the protease inhibitor, SBTI, and the washout time for thrombin was markedly shortened (7.4 +/- 2.2 s) when thrombin was washed out by a solution containing soybean trypsin inhibitor. A synthetic thrombin receptor agonist peptide induced IKCa oscillation with shorter latency than thrombin.

  • Perforated Patch-Clamp recording in cardiac myocytes using cation-selective ionophore gramicidin
    American Journal of Physiology-Cell Physiology, 1996
    Co-Authors: Y. Tajima, K. Ono, Norio Akaike
    Abstract:

    Whole cell currents were recorded in single myocytes dissociated from guinea pig ventricles by the Patch-Clamp technique. The addition of 0.1 mg/ml gramicidin D, a cation-selective ionophore, into the pipette solution induced a gradual spontaneous perforation of the Patch membrane under a conventional cell-attached configuration. The access resistance, measured at approximately 12 min after formation of a gigaohm seal, was 9.2 +/- 1.5 M omega (n = 12). The Perforated Patch membrane exhibited ionic selectivity for various monovalent cations, with a relative order of Cs+ (1.11) > K+ (1.0) > Na+ (0.65) >> tris(hydroxymethyl)aminomethane+ (approximately 0) but was not permeable for Cl-. Under the gramicidin-Perforated Patch recording configuration, the cells showed the typical electrophysiological properties for ventricular cells reported previously. The intracellular Cl- concentration, estimated from the reversal potential of the catecholamine-induced Cl- current, was 36.3 +/- 2.9 mM (n = 17). We thus conclude that the gramicidin-Perforated Patch recording mode provides a useful tool for recording the ionic currents while maintaining the intracellular Cl- concentration.

  • Amyloid β protein-induced irreversible current in rat cortical neurones
    Neuroreport, 1994
    Co-Authors: Katsutoshi Furukawa, Yumiko Abe, Norio Akaike
    Abstract:

    The effect of amyloid beta protein (A beta P) was examined in neurones dissociated from rat cortex using the nystatin Perforated Patch-Clamp technique. A beta P at concentrations > 10 nM induced an irreversible slow inward current associated with an increase in membrane conductance. The time lag until the appearance of the effect of A beta P shortened in a concentration-dependent manner. When extracellular Na+ and Cl-, and intracellular K+ were replaced by equimolar N-methyl glucamine, isothionate- and Cs+, respectively, the membrane conductance and the reversal potential were not affected. Even when an internal solution including 1,2-bis(O-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (20 mM) was used, the effect of A beta P did not alter. It is suggested that A beta P binds to the neuronal membrane and opens non-selective ion channels, resulting in neuronal degeneration.

  • Glycine response in acutely dissociated ventromedial hypothalamic neuron of the rat: new approach with gramicidin Perforated Patch-Clamp technique
    Journal of neurophysiology, 1994
    Co-Authors: Yumiko Abe, Katsutoshi Furukawa, Yasuto Itoyama, Norio Akaike
    Abstract:

    1. We investigated the glycine-induced response in ventromedial hypothalamic (VMH) neurons freshly dissociated from 8- to 12-day-old rats using the nystatin and gramicidin Perforated Patch recording modes. The nystatin-formed pores in the plasma membrane are permeable for both monovalent cations and anions, whereas those formed by gramicidin are permeable only to monovalent cations. Therefore, when the Patch-pipette contains 150 mM Cl- and gramicidin, the physiological intracellular Cl- concentration ([Cl-]i) is undisturbed in the cell-attached condition of the pipette. 2. At holding potentials of -40 to -60 mV, glycine induced inward currents and outward currents in the nystatin and gramicidin Perforated Patch recording modes, respectively. The values of the half-maximum effective concentration (EC50) and the Hill coefficient in the concentration-response relationships of the glycine responses were 2.9 x 10(-5) M, 1.1, and 4.2 x 10(-5) M, 1.4, respectively. These values were quite similar in both recording modes. 3. The reversal potentials of the glycine responses (EGly) were -1.5 mV in the nystatin Perforated Patch recording and -75.0 to -24.8 mV in the gramicidin Perforated Patch recording. 4. Strychnine (3 x 10(-8) M) inhibited the glycine-induced outward currents in a competitive manner and the half-inhibition concentration (IC50) of strychnine on the 10(-4) M glycine-induced response was 1.9 x 10(-8) M. 5. The physiological [Cl-]i in the VMH neurons calculated from the EGly obtained by the gramicidin Perforated Patch mode ranged from 6.0 to 43.8 mM (n = 28).

A. S. Grichenko - One of the best experts on this subject based on the ideXlab platform.

  • The regulation of L-type Ca2+ currents in rat cardiac myocytes.
    Membrane & cell biology, 2000
    Co-Authors: A. F. Korystova, A. S. Grichenko
    Abstract:

    The regulation of L-type Ca2+ current in isolated rat cardiac cells was studied using the Perforated Patch-Clamp technique. A dual effect of the cAMP-dependent phosphorylation activator, isoproterenol, at different holding potentials (V(h)) was shown. The currents increased at V(h) = -50 mV and decreased at V(h) = -30 mV. A dihydropyridine agonist, BAY K 8644, and isoproterenol had an additive effect on the activation of Ca2+ channels at holding potentials close to the resting potential. The additivity was disturbed at more positive V(h). The activating effect of BAY K 8644 did not virtually change in the presence of a protein kinase blocker, H8, and a phosphatase activator, acetylcholine. The results were interpreted within the framework of a two-site phosphorylation model with two independent pathways of Ca2+ current regulation.

  • Effect of isoproterenol on the L-type Ca2+ current in cardiac cells from rats and hybernating ground squirrels.
    Bioscience reports, 1999
    Co-Authors: Yu. M. Kokoz, A. S. Grichenko, A. F. Korystova
    Abstract:

    The Perforated Patch Clamp method was used to study the effect of the agonist of beta-adrenoreceptors isoproterenol on L-type Ca2+ current in cardiocytes of rats and ground squirrels in two states: active and hibernating. It is shown that isoproterenol exerts a dual effect on Ca2+ currents of rats and ground squirrels in the active state: at Vh = −50 mV, the current increases, whereas at Vh = −30 mV, it decreases. In hibernating ground squirrels, the dual effect of isoproterenol is not observed: isoproterenol increases Ca2+ current at any Vh values. The hypothesis is put forward that, during the entrance of ground squirrels into hibernation, the phosphorylation of one of the sites (not cAMP-dependent) of L-type Ca2+ channels is blocked.

  • Effect of Isoproterenol on the L-type Ca^2+ Current in Cardiac Cells from Rats and Hybernating Ground Squirrels
    Bioscience Reports, 1999
    Co-Authors: Yu. M. Kokoz, A. F. Korystova, A. S. Grichenko, D. A. Lankina, N. I. Markevich
    Abstract:

    The Perforated Patch Clamp method was used to study the effect of the agonist of beta-adrenoreceptors isoproterenol on L-type Ca^2+ current in cardiocytes of rats and ground squirrels in two states: active and hibernating. It is shown that isoproterenol exerts a dual effect on Ca^2+ currents of rats and ground squirrels in the active state: at V _h = −50 mV, the current increases, whereas at V _h = −30 mV, it decreases. In hibernating ground squirrels, the dual effect of isoproterenol is not observed: isoproterenol increases Ca^2+ current at any V _h values. The hypothesis is put forward that, during the entrance of ground squirrels into hibernation, the phosphorylation of one of the sites (not cAMP-dependent) of L-type Ca^2+ channels is blocked.

Reinhard Predel - One of the best experts on this subject based on the ideXlab platform.

  • Analysis of Single Neurons by Perforated Patch Clamp Recordings and MALDI-TOF Mass Spectrometry.
    ACS chemical neuroscience, 2018
    Co-Authors: Susanne Neupert, Peter Kloppenburg, Debora Fusca, Reinhard Predel
    Abstract:

    Single-cell mass spectrometry has become an established technique to study specific molecular properties such as the neuropeptide complement of identified neurons. Here, we describe a strategy to characterize, by MALDI-TOF mass spectrometry, neurochemical composition of neurons that were identified by their electrophysiological and neuroanatomical characteristics. The workflow for the first time combined Perforated Patch Clamp recordings with dye loading by electroporation for electrophysiological and neuroanatomical characterization as well as chemical profiling of somata by MALDI-TOF mass spectrometry with subsequent immunohistochemistry. To develop our protocol, we used identified central olfactory neurons from the American cockroach Periplaneta americana. First, the combined approach was optimized using a relative homogeneous, well-characterized neuron population of uniglomerular projection neurons, which show acetylcholine esterase immunoreactivity. The general applicability of this approach was veri...

Judith K. Gwathmey - One of the best experts on this subject based on the ideXlab platform.