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Koselski M, Olszewska A, Hordyjewska A, Malecka-Massalska T, Trebacz K. Three types of ion channels in the cell membrane of mouse fibroblasts. Physiol Res 2017; 66:63-73. [PMID: 27782747 DOI: 10.33549/physiolres.933358] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Patch clamp recordings carried out in the inside-out configuration revealed activity of three kinds of channels: nonselective cation channels, small-conductance K(+) channels, and large-conductance anion channels. The nonselective cation channels did not distinguish between Na(+) and K(+). The unitary conductance of these channels reached 28 pS in a symmetrical concentration of 200 mM NaCl. A lower value of this parameter was recorded for the small-conductance K(+) channels and in a 50-fold gradient of K(+) (200 mM/4 mM) it reached 8 pS. The high selectivity of these channels to potassium was confirmed by the reversal potential (-97 mV), whose value was close to the equilibrium potential for potassium (-100 mV). One of the features of the largeconductance anion channels was high conductance amounting to 493 pS in a symmetrical concentration of 200 mM NaCl. The channels exhibited three subconductance levels. Moreover, an increase in the open probability of the channels at voltages close to zero was observed. The anion selectivity of the channels was low, because the channels were permeable to both Cl(-) and gluconate - a large anion. Research on the calcium dependence revealed that internal calcium activates nonselective cation channels and small-conductance K(+) channels, but not largeconductance anion channels.
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Affiliation(s)
- M Koselski
- Department of Biophysics, Institute of Biology and Biochemistry, Maria Curie-Skłodowska University, Lublin, Poland.
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Barnabé GF, Schwindt TT, Calcagnotto ME, Motta FL, Martinez G, de Oliveira AC, Keim LMN, D'Almeida V, Mendez-Otero R, Mello LE. Chemically-induced RAT mesenchymal stem cells adopt molecular properties of neuronal-like cells but do not have basic neuronal functional properties. PLoS One 2009; 4:e5222. [PMID: 19370156 PMCID: PMC2667250 DOI: 10.1371/journal.pone.0005222] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2008] [Accepted: 03/12/2009] [Indexed: 02/07/2023] Open
Abstract
Induction of adult rat bone marrow mesenchymal stem cells (MSC) by means of chemical compounds (beta-mercaptoethanol, dimethyl sulfoxide and butylated hydroxyanizole) has been proposed to lead to neuronal transdifferentiation, and this protocol has been broadly used by several laboratories worldwide. Only a few hours of MSC chemical induction using this protocol is sufficient for the acquisition of neuronal-like morphology and neuronal protein expression. However, given that cell death is abundant, we hypothesize that, rather than true neuronal differentiation, this particular protocol leads to cellular toxic effects. We confirm that the induced cells with neuronal-like morphology positively stained for NF-200, S100, beta-tubulin III, NSE and MAP-2 proteins. However, the morphological and molecular changes after chemical induction are also associated with an increase in the apoptosis of over 50% of the plated cells after 24 h. Moreover, increased intracellular cysteine after treatment indicates an impairment of redox circuitry during chemical induction, and in vitro electrophysiological recordings (patch-clamp) of the chemically induced MSC did not indicate neuronal properties as these cells do not exhibit Na(+) or K(+) currents and do not fire action potentials. Our findings suggest that a disruption of redox circuitry plays an important role in this specific chemical induction protocol, which might result in cytoskeletal alterations and loss of functional ion-gated channels followed by cell death. Despite the neuronal-like morphology and neural protein expression, induced rat bone marrow MSC do not have basic functional neuronal properties, although it is still plausible that other methods of induction and/or sources of MSC can achieve a successful neuronal differentiation in vitro.
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Affiliation(s)
- Gabriela F. Barnabé
- Departamento de Fisiologia, Universidade Federal de São Paulo (UNIFESP), São Paulo, São Paulo, Brazil
| | - Telma T. Schwindt
- Departamento de Fisiologia, Universidade Federal de São Paulo (UNIFESP), São Paulo, São Paulo, Brazil
| | - Maria E. Calcagnotto
- Departamento de Fisiologia, Universidade Federal de São Paulo (UNIFESP), São Paulo, São Paulo, Brazil
| | - Fabiana L. Motta
- Departamento de Fisiologia, Universidade Federal de São Paulo (UNIFESP), São Paulo, São Paulo, Brazil
| | - Gilberto Martinez
- Departamento de Biofísica, Universidade Federal de São Paulo (UNIFESP), São Paulo, São Paulo, Brazil
| | - Allan C. de Oliveira
- Departamento de Pediatria, Universidade Federal de São Paulo (UNIFESP), São Paulo, São Paulo, Brazil
| | - Leda M. N. Keim
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, Rio de Janeiro, Brazil
| | - Vânia D'Almeida
- Departamento de Pediatria, Universidade Federal de São Paulo (UNIFESP), São Paulo, São Paulo, Brazil
- Departamento de Biociências, Universidade Federal de São Paulo (UNIFESP), Santos, São Paulo, Brazil
| | - Rosália Mendez-Otero
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, Rio de Janeiro, Brazil
| | - Luiz E. Mello
- Departamento de Fisiologia, Universidade Federal de São Paulo (UNIFESP), São Paulo, São Paulo, Brazil
- * E-mail:
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Lim I, Yun J, Kim S, Lee C, Seo S, Kim T, Bang H. Nitric oxide stimulates a large-conductance Ca-activated K+ channel in human skin fibroblasts through protein kinase G pathway. Skin Pharmacol Physiol 2005; 18:279-87. [PMID: 16145282 DOI: 10.1159/000088013] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2005] [Accepted: 06/21/2005] [Indexed: 11/19/2022]
Abstract
In order to investigate the large-conductance Ca(2+)-activated K(+) (BK(Ca)) channel and determine the effects of nitric oxide (NO) on the channel in human skin fibroblasts, we performed electrophysiological patch clamp recordings on 5th-passage cells of human genital skin cultures. The whole-cell outward K(+) current was increased with depolarization, and proved to be sensitive to NS1619 (a selective BK(Ca) channel activator) and iberiotoxin (a specific BK(Ca )channel inhibitor). The single-channel currents showed 226 pS of mean conductance in symmetrical K(+). Sodium nitroprusside (SNP; an NO donor) significantly increased the K(+) current amplitude in the whole-cell mode, and open probability of the channel (NPo) in the cell-attached mode, but not in the inside-out mode. S-nitroso-N-acetylpenicillamine (an NO donor) and 8-Br-cGMP (a membrane-permeant cGMP analogue) also increased the BK(Ca )channel activity. The stimulatory effect of SNP on BK(Ca) channels was inhibited by pretreatment with 1H-[1,2,4]-oxadiazolo[4,3-a]quinoxalin-1-one (a soluble guanylyl cyclase inhibitor), or KT5823 [a specific protein kinase G (PKG) inhibitor]. Cytoplasmic PKG also increased the channel activity in inside-out patches. In conclusion, the present data indicate that BK(Ca) channels constitute a significant fraction of K(+) current in human skin fibroblasts, and that NO increases NPo of BK(Ca) channels, which are mediated via the cGMP/PKG pathway, without direct effects on the channel.
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Affiliation(s)
- I Lim
- Department of Physiology, College of Medicine, Chung-Ang University, Seoul, Korea.
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Takeuchi K, Fukuda A, Kanayama N. Effect of urinary trypsin inhibitor on potassium currents: fetus modulates membrane excitability by production of UTI. Acta Obstet Gynecol Scand 2003; 83:6-11. [PMID: 14678080 DOI: 10.1111/j.1600-0412.2004.00268.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND Amniotic fluid contains a significant level of urinary trypsin inhibitor (UTI). Previously, we reported that UTI inhibits calcium influx of myometrium and it is effective in preventing uterine contraction. This study examined the effects of UTI upon potassium channels, which is important for membrane excitability. METHODS Whole-cell patch-clamp recordings were performed in fibroblasts derived from human fetal skin. Potassium currents were recorded and the effects of exogenous UTI and/or cadmium determined. RESULTS Tetraethylammonium sensitive potassium currents were elicited by step or ramp stimulations at depolarized membrane potentials (over +30 mV). Administration of 1 micro M UTI significantly increased these potassium currents by 16.9%. When calcium channels were blocked by the administration of cadmium, UTI increased the rest of the potassium currents by 4.8%. This indicates that UTI increased calcium-dependent potassium currents by 94.8% but only increased voltage-dependent potassium currents by 4.8%. CONCLUSIONS Urinary trypsin inhibitor is a physiological substance of fetal origin that modulates calcium-dependent and voltage-dependent potassium channels. These data suggest that UTI is capable of regulating the membrane properties of the fetal and myometrial cells in contact with amniotic fluid.
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Affiliation(s)
- Kinya Takeuchi
- Department of Obstetrics and Gynecology, Hamamatsu University School of Medicine, 1-20-1 Handayama, Hamamatsu, Shizuoka 431-3192, Japan.
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Cox RH, Folander K, Swanson R. Differential Expression of Voltage-Gated K
+
Channel Genes in Arteries From Spontaneously Hypertensive and Wistar-Kyoto Rats. Hypertension 2001; 37:1315-22. [PMID: 11358947 DOI: 10.1161/01.hyp.37.5.1315] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
—Voltage-gated K
+
currents play an important role in determining membrane potential, intracellular Ca
2+
, and contraction in arterial smooth muscle. In this study, the expression of genes encoding voltage-gated K
+
channels of the Kv1.X family was compared in arteries from spontaneously hypertensive rats (SHR) and Wistar-Kyoto rats (WKY). Expression of Kv1.X in thoracic aorta, mesenteric arteries, tail artery, and heart was determined, both qualitatively and quantitatively, by reverse transcription–polymerase chain reaction. Our results demonstrate distinct but overlapping patterns of expression in vascular tissues. In general, Kv1.2 and Kv1.5 were most highly represented, and the levels of Kv1.2 were significantly larger in all tissues from SHR. Levels of Kv1.5 in arteries did not differ significantly between strains but were greater in SHR heart. Moderate levels of Kv1.3 and Kvβ1.1 expression were also found in all tissues and were larger in SHR. Kv1.1 expression was not different between the 2 strains, and no significant expression of Kv1.4 (except in heart and aorta), Kv1.6, or Kvβ2.1 was observed in either strain. Kv1.2 and Kv1.5 transcripts represent ≈1 to 2 parts/10
5
of total mesenteric arterial RNA with ≈2- to 5-fold lower levels in aorta and tail artery. Whole-cell voltage-gated K
+
channel currents, recorded from mesenteric arterial myocytes, were larger in SHR than WKY (eg, at 0 mV: 7.3±0.8 versus 10.9±1.2 pA/pF). The voltage dependence of activation was more negative in SHR (V
0.5
: −20±4 mV versus −32±3 mV) but that of availability was not different. These results indicate that Kv1.X genes are differentially expressed between WKY and SHR (especially Kv1.2 and Kvβ1.1). These differences in gene expression are associated with a greater voltage-gated K
+
channel current density in SHR and shifted voltage-dependent activation compared with WKY. These differences may be a compensatory mechanism related to the membrane potential depolarization in SHR or some manifestation thereof.
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Affiliation(s)
- R H Cox
- Department of Physiology, University of Pennsylvania, Philadelphia, USA
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