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1

Potassium channels in brain mitochondria

100%
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.
2

Reconstitution of brain mitochondria inner membrane into planar lipid bilayer

63%
Kulawiak B., Bednarczyk P.
Acta Neurobiologiae Experimentalis
|
2005
|
tom 65
|
nr 3
Ion channels are present in the inner mitochondrial membrane. They play an important role in cellular processes. Potassium and chloride channels are involved in regulation of mitochondrial volume, membrane potential and acidification. The mitochondrial potassium channels have been suggested as triggers and end effectors in cytoprotection. In our study we measured single channel activities after reconstitution of submitochondrial particles from rat brain mitochondria into planar lipid membranes. After incorporation, two different potassium selective currents were recorded with single channel conductance from 260 to 320 pS and from 70 to 90 pS in gradient (cis/trans) 50/450 and 50/150 mM KCl solutions, respectively. We also observed activity of the chloride ion channel. The measured single channel conductance was from 80 to 90 pS in gradient (cis/trans) 50/450 mM KCl solution. Our results suggest that various ion channels are present in the inner mitochondrial membrane of brain mitochondria.
3

Ion channels of the skin mitochondria

63%
Bednarczyk P., Szewczyk A.
Acta Neurobiologiae Experimentalis
|
2014
|
tom 74
|
nr 3
Potassium channels have been found in the inner mitochondrial membranes of various cells. The activation of these channels is cytoprotective. Hence, the identification of ion channels present in the inner mitochondrial membrane of skin cells is important in distinguishing possible protective mechanisms. In our study, inner membrane mitochondrial channels of the keratinocyte and fibroblast were investigated using a patch-clamp. In the inner mitochondrial membrane of fibroblast we detected large-conductance Ca2+-regulated and ATP-regulated potassium channels. In keratinocytes mitochondria we observed potassium-selective channel with a conductance of 83 pS. The channel activity was inhibited by acidic pH and lidocaine. Additionally, channel knockdown decreased viability after UVB radiation exposure. Our findings indicate presence of the potassium channels in the inner mitochondrial membranes of human skin and their possible role in protection. Study was supported by grant MERIS PBS1/B8/1/2012
4

Single channel measurements of ATP regulated potassium channel from rat brain mitochondria

51%
Choma K., Bednarczyk P., Szewczyk A., Dolowy K.
Acta Biochimica Polonica
|
2006
|
tom 53
|
nr Supplement 1
5

Potassium channel of inner membranes of cardiac mitochondria

51%
Bednarczyk P., Kicinska A., Dolowy K., Szewczyk A.
Acta Biochimica Polonica
|
2003
|
tom 50
|
nr Supplement 1
6

Energia odpadowa w mleczarstwie. Określenie wielkości energii odpadowej w zakładzie mleczarskim z proszkownią

51%
Budny J., Kaczorek J., Bednarczyk P., Sienkiewicz S.
Przegląd Mleczarski
|
1989
|
nr 08
7

Calcium regulated potassium channel is present in endothelial mitochondria

51%
Bednarczyk P., Koziel A., Jarmuszkiewicz W., Szewczyk A.
Current Topics in Biophysics. Supplement
|
2013
|
tom 36
|
nr 2A: Posters
8

pH and nucleotide modulation of mitochondrial ATP-regulated potassium channel

51%
Bednarczyk P., Dolowy K., Szewczyk A.
Acta Biochimica Polonica
|
2007
|
tom 54
|
nr Supplement 4
9

Mitochondrial regulation of mitochondrial potassium channels

51%
Szewczyk A., Kulawiak B., Bednarczyk P., Koprowski P.
Acta Biochimica Polonica
|
2018
|
tom 65
|
nr S2
10

Transmembrane segment M2 of glycine receptor as a model system for the pore-forming structure of ion channels

51%
Bednarczyk P., Szewczyk A., Dolowy K.
Acta Biochimica Polonica
|
2002
|
tom 49
|
nr 4
The glycine receptor belongs to the ligand-gated ion channel superfamily. It is a chlo­ride conducting channel composed of four transmembrane domains. It was previously shown that the second transmembrane domain (M2) of the glycine receptor forms an ion conduction pathway throught lipid bilayers. The amino-acid sequence of the transmembrane segment M2 of the glycine receptor has a high homology to all recep­tors of the ligand-gated ion channel superfamily. In our report, we have used a syn­thetic M2 peptide. It was incorporated into a planar membrane of known lipid compo­sition and currents induced by M2 were measured by the Black Lipid Membrane tech­nique. When the planar lipid bilayer was composed of 75% phosphatidylethanolamine and 25% phosphatidylserine, the reversal potential measured in a 150/600 mM KCl (cis/trans) gradient was -19 mV suggesting that the examined pore was preferential to anions, Pk/Pci = 0.25. In contrast, when 75% phosphatidylserine and 25% phosphatidylethanolamine was used, the reversal potential was +20 mV and the pore was preferential to cations, Pk/Pci = 4.36. Single-channel currents were recorded with two predominant amplitudes corresponding to the main-conductance and sub-conductance states. Both conductance states (about 12 pS and 30 pS) were mea­sured in a symmetric solution of 50 mM KCl. The observed single-channel properties suggest that the selectivity and conductance of the pore formed by the M2 peptide of the glycine receptor depend on the lipid composition of the planar bilayer.
11

Effectors of large-conductance calcium-activated potassium channel modulate glutamate excitotoxicity in organotypic hippocampal slice cultures

45%
Piwonska M., Szewczyk A., Schroder U. H., Reymann K. G., Bednarczyk P.
Acta Neurobiologiae Experimentalis
|
2016
|
tom 76
|
nr 1
Mitochondria have been suggested as a potential target for cytoprotective strategies. It has been shown that increased K+ uptake mediate by mitochondrial ATP-regulated potassium channels (mitoKATP channel) or large-conductance Ca2+-activated potassium channels (mitoBKCa channel) may provide protection in different models of cell death. Since recent findings demonstrated the presence of BKCa channels in neuronal mitochondria, the goal of the present study was to test the potential neuroprotective effects of BKCa channel modulators. Using organotypic hippocampal slice cultures exposed to glutamate, we demonstrated that preincubation of the slices with the BKCa channel opener NS1619 resulted in decreased neuronal cell death measured as reduced uptake of propidium iodide. This neuroprotective effect was reversed by preincubation with the BKCa channel inhibitors paxilline and Iberiotoxin (IbTx). Moreover, mitochondrial respiration measurements revealed that NS1619 induced an IbTx-sensitive increase in state 2 respiration of isolated brain mitochondria. In addition, electrophysiological patch-clamp studies confirmed the presence of BKCa channels in mitoplasts isolated from embryonic hippocampal cells. Taken together, our results confirm presence of BKCa channel in rat hippocampal neurons mitochondria and suggest putative role for mitoBKCa in neuroprotection.
12

Flavonoid-induced changes in oxygen consumption and mitochondrial membrane potential in isolated endothelial mitochondria

45%
Kicinska A., Bednarczyk P., Kampa R., Szewczyk W., Jarmuszkiewicz W.
Acta Biochimica Polonica
|
2018
|
tom 65
|
nr S2
13

BK-DEC splice variant forms a functional BKCa channel in the inner mitochondrial membrane

45%
Kucman S. K., Jedraszko J., Bednarczyk P., Szewczyk A., Kulawiak B.
Acta Biochimica Polonica
|
2018
|
tom 65
|
nr S2
14

Single-channel properties of the ROMK2-pore-forming subunit of the mitochondrial ATP-regulated potassium channel

45%
Kulawiak B., Laskowski M., Augustynek B., Bednarczyk P., Szewczyk A.
Acta Biochimica Polonica
|
2018
|
tom 65
|
nr S2
15

Chloride channels in inner mitochondrial membrane

45%
Koszela-Piotrowska I., Choma K., Bednarczyk P., Dolowy K., Szewczyk A.
Acta Biochimica Polonica
|
2006
|
tom 53
|
nr Supplement 1
16

Identification of potassium channels in the mitochondria of human bronchial epithelial cells

45%
Sek A., Kampa R., Kulawiak B., Szewczyk A., Bednarczyk P.
Acta Biochimica Polonica
|
2018
|
tom 65
|
nr S2
17

A novel voltage-gated potassium channel in hippocampal mitochondria

39%
Kowalczyk J. E., Bednarczyk P., Beresewicz M., Dolowy K., Szewczyk A., Zablocka B.
Acta Neurobiologiae Experimentalis
|
2009
|
tom 69
|
nr 1
Transient cerebral ischemia is known to induce endogenous adaptive mechanisms such as the activation of mitochondrial ATP-sensitive potassium channels or calcium-sensitive largeconductance potassium channels that can prevent or delay neuronal injury. In this study a single channel activity was measured after patch-clamp of the mitoplasts isolated from control gerbil hippocampus. In 70% of the all patches, a potassium selective current was recorded with mean conductance 109 ± 6 pS in symmetrical 150 mM KCl solution. Patch-clamp single channel studies protein showed properties of the voltage-gated potassium channel (Kv channel): it was blocked by negative voltage and margatoxin (MgTx) a specifi c Kv1.3 inhibitor. The inhibition by MgTx was no reversed. The channel was not affected by the other Kv1.3 channel blocker agitoxin-2 at nanomolar range. Additionally, we showed that ATP/Mg2+ complex and low or high concentration of Ca2+ ions have no effects on observed activity of ion channel. Mitochondrial localization of Kv1.3 was verifi ed by western blots using antibodies recognizing peptides located in N- or C-terminal of plasma membrane Kv1.3 protein. N-terminal specifi c antibodies recognized proteins with molecular masses around 95, 62 and 40 kDa in plasma membrane and 60 kDa in mitochondria while C-terminal specifi c antibodies recognized 40 kDa protein in mitochondria. Mitochondrial localization of Kv1.3 protein was also shown by immunohistochemistry. We conclude that gerbil hippocampus mitochondria contain voltagegated potassium channel (mitoKv) with properties similar to the surface membrane Kv1.3 channel which can play an important regulatory role for protection with respect of ischemia-reperfusion phenomena. Supported by Polish Mitochondrial Network MitoNet.pl
18

Cardioprotective flavoniods as natural modulators of mitochondrial potassium channels

39%
Kampa R., Sek A., Kicinska A., Kulawiak B., Jarmuszkiewicz W., Szewczyk A., Bednarczyk P.
Acta Biochimica Polonica
|
2018
|
tom 65
|
nr S2
19

Rola i funkcja kanalow chlorkowych sterowanych potencjalem z rodziny CIC i ich defekty prowadzace do chorob genetycznych

39%
Dolowy K., Bednarczyk P., Hordejuk R., Dworakowska B., Nurowska E., Jarzabek W.
Postępy Higieny i Medycyny Doświadczalnej
|
2002
|
tom 56
|
nr 3
307-313
20

Voltage-gated potassium channel in hippocampus mitochondria

39%
Bednarczyk P., Kowalczyk J. E., Beresewicz M., Dolowy K., Szewczyk A., Zablocka B.
Acta Neurobiologiae Experimentalis
|
2011
|
tom 71
|
nr 1
Transient cerebral ischemia is known to induce endogenous adaptive mechanisms such as the activation of mitochondrial ATP regulated or Ca2+ regulated large conductance potassium channels that can prevent or delay neuronal injury. However, molecular mechanism of this effect remains unclear. In this study, a single channel activity was measured with patch-clamp of the mitoplasts isolated from gerbil hippocampus. In 70% of the all patches, a potassium selective current with properties of the voltage-gated potassium channel (Kv type channel) was recorded with mean conductance 109 ± 6 pS in symmetrical 150 mM KCl solution. Detected channel was blocked by negative voltage and margatoxin (MgTx) a specific Kv1.3 channel inhibitor. The inhibition by MgTx was irreversible. We observed that ATP/Mg2+ complex or Ca2+ ions had no effects on observed activity of ion channel. Additionally, we showed that agitoxin-2 (AgTx-2), potent inhibitor of the voltage-gated potassium channels, was without effect on channel activity. This observation suggests that mitochondrial voltage-gated potassium channel can represent different molecular structure without affinity to AgTx-2 in compare to surface membrane channels. Also, Western blot analysis of mitochondria isolated from gerbil hippocampus and immunohistochemistry on gerbil brain sections confirm the expression of Kv1.3 protein in mitochondria. All together, we conclude that gerbil hippocampal mitochondria contain voltage-gated potassium channel (mitoKv1.3 channel) with properties similar to the surface membrane Kv1.3 channel which can influence function of mitochondria in physiological and pathological conditions. This study was supported by the grant from the Ministry of Science and Higher Education (P-N/31/2006) and Polish Mitochondrial Network MitoNet.pl. P.B. would like to acknowledge to prof. Detlef Siemen for teaching patch-clamp and more discussion during postdoc in Magdeburg supported by EMBO (2006) and DAAD (2008).
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