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1

Intracellular ion channels: properties, function and experimental methodology

100%
Kicinska A., Debska G., Szewczyk A.
Postępy Higieny i Medycyny Doświadczalnej
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2000
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vol. 54
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issue 3
307-316
EN
Ion channels selective for potassium or chloride ions are present in membranes of intracellular organelles such as mitochondria, sarcoplastic (endoplastic) reticulum, nucleus, synaptic vesicles, and chromaffin, and zymogen granules. They are probably important in cellular events such as compensation of electrical charges during intracellular transport of Ca 2+ and H+ and regulation of organelle volume changes. This review describes the basic properties, and current hypotheses concerning the functional role, and some aspects of experimental methodology of intracellular ion channels studies.
2
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Ocena stężenia ATP w Candida albicans w procesie tworzenia form kiełkujących

100%
Dróżdż M. M., Seget S. J., Czuba Z. P.
Annales Academiae Medicae Silesiensis
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2018
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issue 72
240-243
EN
INTRODUCTION: Candida albicans (C. albicans) is part of the natural microbiota of the human body. At the same time, it is one of the most common causes of opportunistic systemic fungal infections. Candida albicans is a poly-morphic microorganism. The change in phenotype is related to the influence of environmental factors. Due to their polymorphic nature, these yeast-like forms can counter mechanisms of phagocytosis. The aim of the study is to eva-luate the adenosine triphosphate (ATP) concentration in the process of forming germ tube forms by C. albicans. MATERIAL AND METHODS: Candida albicans reference strain ATCC 10231 was used for the study. An ATP assay kit by LKB Wallac was used to measure the ATP concentration. The Merck Millipore cell counter Scepter and cell density meter DensiLaMeter II were used to assess the cell count. RESULTS: The ATP concentration after 120 min was higher for C. albicans simulated with L-proline and D-glucose in reference to non-stimulated cells. The highest concentration of ATP was found in the C. albicans cells stimulated with L-proline. Moreover, in this case, the highest number of germ tube forms was found. CONCLUSIONS: 1. The formation of germ tube forms of C. albicans is accompanied by an increase in single cell ATP concentration. 2. Regardless of the type of stimulating substance used in the formation of C. albicans germ tube forms, there is an increase in ATP concentration in a single fungal cell.
PL
WSTĘP: Candida albicans (C. albicans) wchodzi w skład naturalnej mikroflory organizmu człowieka. Jednocześnie jest jedną z najczęstszych przyczyn oportunistycznych grzybic systemowych. Candida albicans jest drobnoustrojem polimorficznym. Zmiana fenotypu związana jest z oddziaływaniem czynników środowiskowych. Dzięki zdolnościom polimorficznym formy drożdżopodobne mogą przeciwstawić się mechanizmom fagocytozy. Celem pracy jest ocena stężenia ATP (adenosine triphosphate) w procesie tworzenia form kiełkujących przez C. albicans. MATERIAŁ I METODY: Do badań wykorzystano wzorcowy szczep C. albicans ATCC 10231. W pomiarach stężenia ATP wykorzystano ATP Assay Kit firmy LKB Wallac. Do oceny liczby komórek użyto urządzenia Scepter firmy Merck Millipore oraz densytometru DensiLaMeter II. WYNIKI: Stężenie ATP po 120 min było wyższe w przypadku komórek C. albicans stymulowanych L-proliną oraz D--glukozą niż w komórkach niestymulowanych. Największe stężenie ATP występowało w komórkach C. albicans poddanych stymulacji L-proliną. Również w tym przypadku występowała największa liczba form kiełkujących. WNIOSKI: 1. Tworzeniu form kiełkujących C. albicans towarzyszy wzrost stężenia ATP w pojedynczej komórce. 2. Niezależnie od rodzaju substancji stymulującej w procesie tworzenia form kiełkujących w C. albicans dochodzi do wzrostu stężenia ATP w przeliczeniu na pojedynczą komórkę grzyba.
3
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ATP a potent regulator of inositol phospholipids-phospholipase C and lipid mediators in brain cortex

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Strosznajder J., Strosznajder R. P.
Acta Neurobiologiae Experimentalis
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1996
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vol. 56
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issue 2
527-534
EN
Adenosine-5'triphosphate (ATP) is stored and co-released with various neurotransmitters but it may also act as a fast excitatory neurotransmitter trough the activation of purinoreceptor(s).In this study the effcet of ATP on phospholipase C (PLC) degrading labelled PtdIns(4,5)P2 and PtdIns in brain cortex slices, brain homogente and subcellular fractions was investigated.It was found the ATP added into brain slices activated significantly and specifically PtdIns(4,5)P2 degradation and this process was inhibited by theophylline.Moreover, ATP maintained a higher level of inositol(1,4,5,)P3 radioactivity in total water-soluble inositol metabolites.However, ATP added directly for the assay of PLC into brain homogenate of subcellular fractions inhibits phosphoinositide degradation in a eceptor-independend manner and suppresses conversion of Ins(1,4,5)P3 into Ins(1,4)P2.Our results indicate that ATP acting extracellularly through a purinergic receptor(s) activates PtdIns(4,5)P2 degradation and release of Ins(1,4,5)P3.ATP acting directly on PLC inhibits in a receptor-independent manner phosphoinositide degradation, and protect against liberation of lipid-derived second messengers.
4

ATP measurement as a rapid test of microbiological contamination

100%
Czaczyk K.
Biotechnologia
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1999
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issue 4
179-185
EN
Bioluminescent measurement of ATP using luciferin/luciferase system is a very sensitive, specific, rapid, and convenient method in microbiology. The use of this method to quantitate viable microbial cells requires the use of various validation procedures and safeguards, depending on the specific application. Most industrial applications of bioluminescent ATP measurement involve detection and quantitation of microbial contamination in a particular product, such as the rapid identification of a critical level of contamination in output material. Cloning of the firefly luciferase gene lux promises to be a much more efficient, consistent and inexpensive source of recombinat enzyme. With the realization of this potential and the marketing of automated luminometers that will undoubtedly be improved greatly in terms of throughput capacity, bioluminescent ATP measurement is becoming the method of choise for large-scale monitoring of viable microbial biomass.
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ATP-binding peptide-hydrogel composite synthesized by molecular imprinting on beads

100%
Takata A., Usui K., Matsui J.
Molecular Imprinting
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2014
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vol. 2
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issue 1
EN
Molecular imprinting has been recognized as a useful technique to produce synthetic mimics of functional proteins, such as antibodies and enzymes. However, only a few studies have examined peptides as starting materials for synthesizing molecularly imprinted polymers in spite of the expectation that peptides would be suitable materials for realizing water-compatibility and proteinlike functions. In this study, molecular imprinting was performed using a vinyl-end-capped on-beads-peptide as functional monomer to produce an on-beads-peptide hydrogel composite selective for ATP; the on-beadspeptide peptide, of which sequence was designed to possess both an adenine-recognition site and phosphate recognition site, was co-polymerized with NIPAM and BIS in the presence of ATP as a template species. The resultant ATP-imprinted composite showed 14-times higher affinity and an enhanced selectivity towards ATP, suggesting that the peptide conformation, i.e. a mutual orientation of the two binding sites, was pre-organized and immobilized in a manner where the ATP binding is more favored.
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Enhanced responsiveness of rat cardiac myocytes to muscarinic cholinergic stimulation during chemically-induced hypoxia

100%
Majewski M., Laskowska-Bozek H., Moutris J. A., Maslinski S., Ryzewski J.
Acta Neurobiologiae Experimentalis
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1993
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vol. 53
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issue 1
79-91
EN
In contrast to adrenaline, exogenously administrated cholinergic agonist, carbachol have very little effect on the contractility of rat cardiac myocytes, unless its contracitle has been increased by adrenergic agonist. This interaction between the muscarinic and adrenergic pathways has been suggested to be the major means by which muscarinic agonist alters adrenergic function. When the cardiac myocytes were incubated in the medium contained the mitochondrial respiratory inhibitor potassium cyanide (chemically-induced hypoxia)the spontaneous contractility was ceased. The contractility partly recovered that during chemical hypoxia, in which cellular ATP is decreased (37% of control), the respponsiveness of myocytes to muscarinic cholinergic stimulation significantly increase. Contraction of myocytes, stimulated by adrenaline was inhibited by carbachol in control cells as well as in cells with chemically-induced hypoxia. This increase in physiological response to muscarinic stimulation was associated with an increase of muscarinic receptors (630%). The results support the hypothesis that in ischaemic/hypoxic myocardium the role of cholinergic system may be more important than previously assumed.
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Extracellular ATP as a neurotransmitter: its role in synaptic plasticity in the hippocampus

100%
Wieraszko A.
Acta Neurobiologiae Experimentalis
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1996
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vol. 56
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issue 2
637-648
EN
Growing evidence indices that ATP may play a very important role in Long-Term Potentiation (LTP), a neurophysiological process that has been implicated in memory formation.LTP is an enhancement of synaptic strength induced by a specific pattern of high frequency stimulation, or by application of exogenous ATP.In the hippocampus LTP-inducing stimulation is accompanied by a massive Ca2+ -dependent release of ATP from presympatic terminals.Released extracellular ATP may either intract with numerous types of ATP receptors present on the neuronal surface, or serve as a substrate for ecto-protein phosphorylation.The results of combined electrophysiological and biochemical experiments indicate that participation of extracellular ATP in the ecto-protein phosphorylation process is most likely involved in the permanent amplification of the synaptic response in the hippocampus.
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Intracellular potassium and chloride channels: An update.

75%
Dębska G., Kicińska A., Skalska J., Szewczyk A.
Acta Biochimica Polonica
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2001
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vol. 48
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issue 1
137-144
EN
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.
9
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Elevation of the adenylate pool in rat cardiomyocytes by S-adenosyl-L-methionine.

75%
Smolenski R. T.
Acta Biochimica Polonica
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2000
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vol. 47
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issue 4
1171-1178
EN
Rapid resynthesis of the adenylate pool in cardiac myocytes is important for recovery of contractility and normal function of regulatory mechanisms in the heart. Adenosine and adenine are thought to be the most effective substrates for nucleotide synthesis, but the possibility of using other compounds has been studied very little in cardiomyocytes. In the present study, the effect of S-adenosyl-L-methionine (SAM) on the adenylate pool of isolated cardiomyocytes was investigated and compared to the effect of adenine and adenosine. Adult rat cardiomyocytes were isolated using the collagenase perfusion technique. The cells were incubated in the presence of adenine derivatives for 90 min followed by nucleotide determination by HPLC. The concentrations of adenine nucleotides expressed in nmol/mg of cell protein were initially 22.1 ± 1.4, 4.0 ± 0.3 and 0.70 ± 0.08 for ATP, ADP and AMP, respectively (n = 10, ±S.E.M.), and the total adenylate pool was 26.8 ± 1.6. In the presence of 1.25 mM SAM in the medium, the adenylate pool increased by 5.2 ± 0.4 nmol/mg of cell protein, but only if 1 mM ribose was additionally present in the medium. No changes were observed with SAM alone. A similar increase (by 4.9 ± 0.6 nmol/mg protein) was observed after incubation with 1.25 mM adenine plus 1 mM ribose, but no increase was observed if ribose was omitted. Adenosine at 0.1 or 1.25 mM concentrations also caused an increase in the adenylate pool (by 5.2 ± 1.0 and 5.2 ± 0.9 nmol/mg protein, respectively), which in contrast to the SAM or adenine was independent of the additional presence of ribose. Thus, S-adenosyl-L-methionine could be used as a precursor of the adenylate pool in cardiomyocytes, which is as efficient in increasing the adenylate pool after 90 min of incubation as adenosine or adenine. Nucleotide synthesis from SAM involves the formation of adenine as an intermediate with its subsequent incorporation by adenine phosphoribosyltransferase.
10
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ATP-sensitive K+ transport in adrenal chromaffin granules

75%
Szewczyk A., Lobanov N. A., Kicinska A., Wojcik G., Nalecz M. J.
Acta Neurobiologiae Experimentalis
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2001
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vol. 61
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issue 1
1-12
EN
In the present study the influx of 86Rb+, a K+ analogue, was studied in mitochondria, microsomes and chromaffin granules prepared from adrenal gland medulla. The most active electrogenic 86Rb+ transport was found in the membrane fraction identified as chromaffin granules by marker enzyme estimation. The transport was found to be sensitive to ATP, ATPS, ADP and to the triazine dyes, but not to AMP and cAMP. The inhibition induced by ATP was observed in the absence of externally added Mg2+, suggesting that a free nucleotide, rather than the ATP-Mg complex, was required for inhibition. Furthermore, the 86Rb+ influx was found to be inhibited by Mg2+ alone, but not by Ca2+ and antidiabetic sulfonylureas. The 86Rb+ influx was not stimulated by potassium channel openers. In conclusion, our results indicate that an electrogenic, ATP-sensitive potassium transport system operates in the chromaffin granule membrane.
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Purinergic signaling in the pancreas and the therapeutic potential of ecto-nucleotidases in diabetes

75%
Cieślak M., Roszek K.
Acta Biochimica Polonica
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2014
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vol. 61
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issue 4
655-662
EN
It is widely accepted that purinergic signaling is involved in the regulation of functions of all known tissues and organs. Extracellular purines activate two classes of receptors, P1-adenosine receptors and P2-nucleotide receptors, in a concentration-dependent manner. Ecto-enzymes metabolizing nucleotides outside the cell are involved in the termination of the nucleotide signaling pathway through the release of ligands from their receptors. The pancreas is a central organ in nutrient and energy homeostasis with endocrine, exocrine and immunoreactive functions. The disturbances in cellular metabolism in diabetes mellitus lead also to changes in concentrations of intra- and extracellular nucleotides. Purinergic receptors P1 and P2 are present on the pancreatic islet cells as well as on hepatocytes, adipocytes, pancreatic blood vessels and nerves. The ATP-dependent P2X receptor activation on pancreatic β-cells results in a positive autocrine signal and subsequent insulin secretion. Ecto-NTPDases play the key role in regulation of extracellular ATP concentration. These enzymes, in cooperation with 5'-nucleotidase can significantly increase ecto-adenosine concentration. It has been demonstrated that adenosine, through activation of P1 receptors present on adipocytes and pancreatic islets cells, inhibits the release of insulin. Even though we know for 50 years about the regulatory role of nucleotides in the secretion of insulin, an integrated understanding of the involvement of purinergic signaling in pancreas function is still required. This comprehensive review presents our current knowledge about purinergic signaling in physiology and pathology of the pancreas as well as its potential therapeutic relevance in diabetes.
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Mitochondrial potassium and chloride channels.

75%
Kicińska A., Dębska G., Kunz W., Szewczyk A.
Acta Biochimica Polonica
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2000
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vol. 47
|
issue 3
541-551
EN
Channels selective for potassium or chloride ions are present in inner mitochondrial membranes. They probably play an important role in mitochondrial events such as the formation of ΔpH and regulation of mitochondrial volume changes. Mitochondrial potassium and chloride channels could also be the targets for pharmacologically active compounds such as potassium channel openers and antidiabetic sulfonylureas. This review describes the properties, pharmacology, and current observations concerning the functional role of mitochondrial potassium and chloride channels.
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Directionality of kinesin motors.

63%
Kasprzak A. A., Hajdo Ł.
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vol. 49
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issue 4
813-821
EN
Kinesins are molecular motors that transport various cargoes along microtubule tracks using energy derived from ATP hydrolysis. Although the motor domains of kinesins are structurally similar, the family contains members that move on microtubules in opposite directions. Recent biochemical and biophysical studies of several kinesins make it possible to identify structural elements responsible for the different directionality, suggesting that reversal of the motor movement can be achieved through small, local changes in the protein structure.
14
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Cross-talk between the ATP and ADP nucleotide receptor signalling pathways in glioma C6 cells.

63%
Czajkowski R., Barańska J.
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vol. 49
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issue 4
877-889
EN
In this review we summarize the present status of our knowledge on the enzymes involved in the extracellular metabolism of nucleotides and the receptors involved in nucleotide signalling. We focus on the mechanism of the ATP and ADP signalling pathways in glioma C6, representative of the type of nonexcitable cells. In these cells, ATP acts on the P2Y2 receptor coupled to phospholipase C, whereas ADP on two distinct P2Y receptors: P2Y1 and P2Y12. The former is linked to phospholipase C and the latter is negatively coupled to adenylyl cyclase. The possible cross-talk between the ATP-, ADP- and adenosine-induced pathways, leading to simultaneous regulation of inositol 1,4,5-trisphosphate and cAMP mediated signalling, is discussed.
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