Wyniki wyszukiwania

1

Mitochondria and potassium channel openers

100%

Szewczyk A., Kicinska A., Skalska J., Debska G., Berest V.

Cellular and Molecular Biology Letters

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2002

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tom 07

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nr Suppl.

2

On the role of ball and chain interactions in recovery from the inactivation of the shaker potassium channel

88%

Borys P., Grzywna Z. J.

Cellular and Molecular Biology Letters

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2008

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tom 13

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nr 4

526-534

We describe a new factor in the recovery from inactivation in the ball and chain model. We propose a model in which the tension from the chain may help pull the ball away from its binding site, reducing the duration of the inactivation period. A corresponding model was built and analysed.

3

A new double-chamber model of ion channels. Beyond the Hodgkin and Huxley model

88%

Dolowy K.

Cellular and Molecular Biology Letters

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2003

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tom 08

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nr 3

This paper proposes a new double-chamber model (DCM) of ion channels. The model ion channel consists of a series of three pores alternating with two chambers. The chambers are net negatively charged. The chamber’s electric charge originates from dissociated amino acid side chains and is pH dependent. The chamber’s net negative charge is compensated by cations present inside the chamber and in a diffuse electric layer outside the chamber. The pore’s permeability is constant independent of time. One pore of the sodium channel and one of the potassium channel is a voltage-sensing pore. Due to the channel's structure, ions flow through the pores and chambers in a time-dependent manner. The model reproduces experimental voltage clamp and action potential data. The current flowing through a single sodium channel is less then one femtoampere. The DCM is considerably simpler then the Hodgkin and Huxley model (HHM) used to describe the electrophysiological properties of an axon. Unlike the HHM, the DCM can explain refractoriness, anode break excitation, accommodation and the effect of pH and temperature on the channels without additional parameters. In the DCM, the axon membrane shows repetitive activity depending on the channel density, sodium to potassium channel ratio and external potassium concentration. In the DCM, the action potential starts from ‘hot spot areas’ of higher channel densities and a higher sodium to potassium channel ratio, and then propagates through the whole axon.

4

Influence of ion-conformational interaction on channel functionning

88%

Weinreb G. E.

Biophysics of Membrane Transport

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1994

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tom 12

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nr 2

5

Large-conductance K+ channel openers induce death of human glioma cells

75%

Debska-Vielhaber G., Godlewski M. M., Kicinska A., Skalska J., Kulawiak B., Piwonska M., Zablocki K., Kunz W. S., Szewczyk A., Motyl T.

Journal of Physiology and Pharmacology

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2009

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tom 60

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nr 4

27-36

Large-conductance Ca2+-activated K+ channels (BKCa channels) are highly expressed in human glioma cells. It has been reported that BKCa channels are present in the inner mitochondrial membrane of the human glioma cell line LN229. In the present study we investigated whether BKCa-channel openers, such as CGS7181 (ethyl 2-hydroxy-1-[[(4-methylphenyl)amino]oxo]-6-trifluoromethyl-1H-indole-3-carboxylate) and CGS7184 (ethyl 1-[[(4-chlorophenyl) amino]oxo]-2-hydroxy-6-trifluoromethyl-1H-indole-3-carboxylate), affect the functioning of LN229 glioma cell mitochondria in situ. In the micromolar concentration range CGS7181 and CGS7184 induced glioma cell death. Morphological and cytometric analyses confirmed that both substances trigger the glioma cell death. This effect was not inhibited by the pan-caspase inhibitor z-VAD-fmk. Lack of DNA laddering, PARP cleavage, and caspase 3 activation suggested that glioma cell death was not of the apoptotic type. We examined the effect of CGS7184 on mitochondrial membrane potential and mitochondrial respiration. Potassium channel opener CGS7184 increased cell respiration and induced mitochondrial membrane depolarization. The latter was dependent on the presence of Ca2+ in the external medium. It was shown that CGS7184 induced an increase of cytosolic Ca2+ concentration due to endoplasmic reticulum store depletion. In conclusion, our results show that CGS7181 and CGS7184 induce glioma cell death by increasing the cytosolic calcium concentration followed by activation of calpains.

6

Expression level of TRPM7 channel in mammary epithelial cells selected to grow in very low [0.025 mM] and very high [45 mM] magnesium containing media

75%

Simonacci M., Trapani V., Boninsegna A., Cittadini A., Wolf F. I.

Journal of Elementology

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2005

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tom 10

|

nr 4 Suppl.1

97-98

7

Characteristics of anion and SV channels in the vacuoles of the liverwort Conocephalum conicum L.

75%

Dziubinska H., Krol E., Hanaka A., Trebacz K.

Polish Journal of Natural Sciences. Supplement

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2003

|

tom 01

8

Application of the ensemble nonequilibrium response spectroscopy to shaker potassium channel gating

75%

Kargol A.

Cellular and Molecular Biology Letters

|

2004

|

tom 09

|

nr 2

Standard electrophysiology techniques study relaxation transients in voltage-gated ion channels generated by discrete voltage steps. The nonequilibrium response spectroscopy involves analyzing responses to fluctuating potentials. We apply the ensemble NRS method to gating kinetics of Shaker potassium ion channels. We evaluate various proposed Markov models of channel gating from the nonequilibrium response viewpoint. These new NRS protocols can be used to test otherwise indistinguishable models or improve estimates for parameters of channel kinetics models.

9

The modulation of lymphocyte potassium channel activity by membrane lipid metabolites

75%

Teisseyre A., Michalak K., Kuliszkiewicz-Janus M.

Cellular and Molecular Biology Letters

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2002

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tom 07

|

nr Suppl.

10

Changes of pH in Petunia hybrida [Hort.] styles induced by pollination and influence of proton pump and ion channels on its regulation

75%

Filek M., Wedzony M., Bednarska E.

Acta Physiologiae Plantarum

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2003

|

tom 25

|

nr 1

11

Ion current fluctuations in artificial ion track pores - power spectrum and generalized entropy

75%

Wolf A., Siwy Z., Korchev Y. E., Reber N., Spohr R.

Cellular and Molecular Biology Letters

|

1999

|

tom 04

|

nr 4

The ion current through individual etched ion tracks (diameter ≈50 nm, length ≈12 µm) in a poly (ethylene terephthalate) membrane is recorded at pH 7 as function of applied voltage (-5V to +5V) across the membrane. With increasing voltage, the ion current changes abruptly from random oscillations to structured fluctuations. The power spectrum and the generalized entropy of the recorded current reminds of the potassium channel of a locust muscle cell.

12

Divalent cations and protons inhibit Triton X-100 induced ion channels

75%

Rostovtseva T. K.

Biophysics of Membrane Transport

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1994

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tom 12

|

nr 2

13

Modified patch-clamp method for studying ion channels in Stentor coeruleus

75%

Koprowski P., Walerczyk M., Groszynska B., Fabczak H., Kubalski A.

Acta Protozoologica

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1997

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tom 36

|

nr 2

14

Intracellular potassium and chloride channels: An update

75%

Debska G., Kicinska A., Skalska J., Szewczyk A.

Acta Biochimica Polonica

|

2001

|

tom 48

|

nr 1

Channels selective for potassium or chloride ions are present in all intracellular membranes such as mitochondrial membranes, sarcoplasmic/endoplasmic reticulum, nuclear membrane and chromaffin granule membranes. They probably play an important role in events such as acidification of intracellular compartments and regulation of organelle volume. Additionally, intracellular ion channels are targets for pharmacologically active compounds, e.g. mitochondrial potassium channels interact with potassium channel openers such as diazoxide. This review describes current observations concerning the properties and functional roles of intracellular potassium and chloride channels.

15

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The retromer: a multiprotein complex mediating multiple functions

63%

Bayle V., Zelazny E., Miege C., Fobis-Loisy I., Jaillais Y., Gaude T.

BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology

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2013

|

tom 94

|

nr 3

16

On the possible methods for the mathematical description of the ball and chain model of ion channel inactivation

63%

Malysiak K., Grzywna Z. J.

Cellular and Molecular Biology Letters

|

2008

|

tom 13

|

nr 4

535-552

Ion channels are large transmembrane proteins that are able to conduct small inorganic ions. They are characterized by high selectivity and the ability to gate, i.e. to modify their conductance in response to different stimuli. One of the types of gating follows the ball and chain model, according to which a part of the channel’s protein forms a ball connected with the intracellular side of the channel by a polypeptide chain. The ball is able to modify the conductance of the channel by properly binding to and plugging the channel pore. In this study, the polypeptide ball is treated as a Brownian particle, the movements of which are limited by the length of the chain. The probability density of the ball’s position is resolved by different diffusional operators — parabolic (including the case with drift), hyperbolic, and fractional. We show how those different approaches shed light on different aspects of the movement. We also comment on some features of the survival probabilities (which are ready to be compared with electrophysiological measurements) for issues based on the above operators.

17

The impact of hydrogen peroxide and hydroxyl radical on ion channels activation in the liverwort Conocephalum conicum

63%

Brankiewicz W.

BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology

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2013

|

tom 94

|

nr 2

18

Cardiac channelopathies - A too frequently trivialized problem?

63%

Urbanczuk M., Jaroszynski A.

Journal of Pre-Clinical and Clinical Research

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2015

|

tom 09

|

nr 1

19

Endothelium as target for large-conductance calcium-activated potassium channel openers

63%

Wrzosek A.

Acta Biochimica Polonica

|

2009

|

tom 56

|

nr 3

393-404

The endothelium is a highly active organ responsible for vasculatory tone and structure, angiogenesis, as well as hemodynamic, humoral, and inflammatory responses. The endothelium is constantly exposed to blood flow, sheer stress and tension. Endothelial cells are present as a vasculature in every tissue of the body and react to and control its microenvironment. A variety of ion channels are present in the plasma membranes of endothelial cells. These include potassium channels such as inwardly rectifying potassium (Kir) channels, voltage-dependent (Kv) channels, ATP-regulated potassium (KATP) channels and three types of calcium-activated potassium channels (KCa), the large (BKCa), intermediate (IKCa), and small (SKCa) -conductance potassium channels. Potassium current plays a critical role in action potentials in excitable cells, in setting the resting membrane potential, and in regulating neurotransmitter release. Mitochondrial isoforms of potassium channel contribute to the cytoprotection of endothelial cells. Prominent among potassium channels are families of calcium-activated potassium channels, and especially large-conductance calcium-activated potassium channels. The modulation of BKCa channels, which are voltage- and calcium-dependent, has been intensively studied. The BKCa channels show large expression dynamics in endothelial cells and tissue-specific expression of large numbers of alternatively spliced isoforms. In this review, a few examples of the modulatory mechanisms and physiological consequences of the expression of BKCa channels are discussed in relation to potential targets for pharmacological intervention.

20

Potassium channels in brain mitochondria

63%

Bednarczyk P.

Acta Biochimica Polonica

|

2009

|

tom 56

|

nr 3

385-392

Potassium channels are the most widely distributed class of ion channels. These channels are transmembrane proteins known to play important roles in both normal and pathophysiological functions in all cell types. Various potassium channels are recognised as potential therapeutic targets in the treatment of Parkinson's disease, Alzheimer's disease, brain/spinal cord ischaemia and sepsis. In addition to their importance as therapeutic targets, certain potassium channels are known for their beneficial roles in anaesthesia, cardioprotection and neuroprotection. Some types of potassium channels present in the plasma membrane of various cells have been found in the inner mitochondrial membrane as well. Potassium channels have been proposed to regulate mitochondrial membrane potential, respiration, matrix volume and Ca2+ ion homeostasis. It has been proposed that mitochondrial potassium channels mediate ischaemic preconditioning in various tissues. However, the specificity of a pharmacological agents and the mechanisms underlying their effects on ischaemic preconditioning remain controversial. The following potassium channels from various tissues have been identified in the inner mitochondrial membrane: ATP-regulated (mitoKATP) channel, large conductance Ca2+-regulated (mitoBKCa) channel, intermediate conductance Ca2+-regulated (mitoIKCa) channel, voltage-gated (mitoKv1.3 type) channel, and twin-pore domain (mitoTASK-3) channel. It has been shown that increased potassium flux into brain mitochondria induced by either the mitoKATP channel or mitoBKCa channel affects the beneficial effects on neuronal cell survival under pathological conditions. Recently, differential distribution of mitoBKCa channels has been observed in neuronal mitochondria. These findings may suggest a neuroprotective role for the mitoBKCa channel in specific brain structures. This minireview summarises current data on brain mitochondrial potassium channels and the efforts to identify their molecular correlates.

Ograniczanie wyników

Mitochondria and potassium channel openers

On the role of ball and chain interactions in recovery from the inactivation of the shaker potassium channel

A new double-chamber model of ion channels. Beyond the Hodgkin and Huxley model

Influence of ion-conformational interaction on channel functionning

Large-conductance K+ channel openers induce death of human glioma cells

Expression level of TRPM7 channel in mammary epithelial cells selected to grow in very low [0.025 mM] and very high [45 mM] magnesium containing media

Characteristics of anion and SV channels in the vacuoles of the liverwort Conocephalum conicum L.

Application of the ensemble nonequilibrium response spectroscopy to shaker potassium channel gating

The modulation of lymphocyte potassium channel activity by membrane lipid metabolites

Changes of pH in Petunia hybrida [Hort.] styles induced by pollination and influence of proton pump and ion channels on its regulation

Ion current fluctuations in artificial ion track pores - power spectrum and generalized entropy

Divalent cations and protons inhibit Triton X-100 induced ion channels