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Abstract
Neuroglia, the "glue" that fills the space between neurons in the central nervous system, takes active part in nerve cell signaling. Neuroglial cells, astroglia, oligodendroglia, and microglia, are together about as numerous as neurons in the brain as a whole, and in the cerebral cortex grey matter, but the proportion varies widely among brain regions. Glial volume, however, is less than one-fifth of the tissue volume in grey matter. When stimulated by neurons or other cells, neuroglial cells release gliotransmitters by exocytosis, similar to neurotransmitter release from nerve endings, or by carrier-mediated transport or channel flux through the plasma membrane. Gliotransmitters include the common neurotransmitters glutamate and GABA, the nonstandard amino acid d-serine, the high-energy phosphate ATP, and l-lactate. The latter molecule is a "buffer" between glycolytic and oxidative metabolism as well as a signaling substance recently shown to act on specific lactate receptors in the brain. Complementing neurotransmission at a synapse, neuroglial transmission often implies diffusion of the transmitter over a longer distance and concurs with the concept of volume transmission. Transmission from glia modulates synaptic neurotransmission based on energetic and other local conditions in a volume of tissue surrounding the individual synapse. Neuroglial transmission appears to contribute significantly to brain functions such as memory, as well as to prevalent neuropathologies.
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Affiliation(s)
- Vidar Gundersen
- SN-Lab, Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, and CMBN/SERTA/Healthy Brain Ageing Centre, University of Oslo, Oslo, Norway; Department of Neurology, Oslo University Hospital-Rikshospitalet, Oslo, Norway; Center for Healthy Aging, Department of Neuroscience and Pharmacology, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark; and Brain and Muscle Energy Group, Department of Oral Biology and Division of Anatomy, Department of Molecular Medicine, University of Oslo, Oslo, Norway
| | - Jon Storm-Mathisen
- SN-Lab, Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, and CMBN/SERTA/Healthy Brain Ageing Centre, University of Oslo, Oslo, Norway; Department of Neurology, Oslo University Hospital-Rikshospitalet, Oslo, Norway; Center for Healthy Aging, Department of Neuroscience and Pharmacology, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark; and Brain and Muscle Energy Group, Department of Oral Biology and Division of Anatomy, Department of Molecular Medicine, University of Oslo, Oslo, Norway
| | - Linda Hildegard Bergersen
- SN-Lab, Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, and CMBN/SERTA/Healthy Brain Ageing Centre, University of Oslo, Oslo, Norway; Department of Neurology, Oslo University Hospital-Rikshospitalet, Oslo, Norway; Center for Healthy Aging, Department of Neuroscience and Pharmacology, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark; and Brain and Muscle Energy Group, Department of Oral Biology and Division of Anatomy, Department of Molecular Medicine, University of Oslo, Oslo, Norway
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2
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Reid B, Vieira AC, Cao L, Mannis MJ, Schwab IR, Zhao M. Specific ion fluxes generate cornea wound electric currents. Commun Integr Biol 2014. [DOI: 10.4161/cib.15545] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
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3
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Romero TRL, Pacheco DDF, Duarte IDG. Probable involvement of Ca2+-activated Cl− channels (CaCCs) in the activation of CB1 cannabinoid receptors. Life Sci 2013; 92:815-20. [DOI: 10.1016/j.lfs.2012.10.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2012] [Revised: 08/30/2012] [Accepted: 10/11/2012] [Indexed: 11/29/2022]
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Pacheco DDF, Pacheco CMDF, Duarte IDG. δ-Opioid receptor agonist SNC80 induces central antinociception mediated by Ca2+-activated Cl- channels. J Pharm Pharmacol 2012; 64:1084-9. [DOI: 10.1111/j.2042-7158.2012.01472.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Abstract
Objectives
The aim of this study was to determine whether Ca2+-activated Cl- channels (CaCCs) are involved in central antinociception induced by the activation of µ-, δ- and κ-opioid receptors.
Methods
The nociceptive threshold for thermal stimulation was measured using the tail-flick test in Swiss mice. The drugs were administered via the intracerebroventricular route. Probabilities values of P < 0.05 were considered to be statistically significant (analysis of variance/Bonferroni test).
Key findings
The results demonstrate that exposure to the CaCC blocker niflumic acid (2, 4 and 8 µg) partially reverses the central antinociception induced by the δ-opioid receptor agonist SNC80 ((+)-4-[(αR)-α-((2S,5R)-4-allyl-2,5-dimethyl-1-piperazinyl)-3-methoxybenzyl]-N,N-diethylbenzamide; 4 µg). In contrast, niflumic acid did not modify the antinociceptive effect of the µ-opioid receptor agonist [D-Ala2, N-Me-Phe4, Gly5-ol]-enkephalin (0.5 µg) or κ-opioid receptor agonist bremazocine (4 µg).
Conclusions
These data provide evidence for the involvement of CaCCs in δ-opioid receptor-induced central antinociception resulting from receptor activation by the agonist SNC80. CaCC activation does not appear to be involved when µ- and κ-opioid receptors are activated.
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Affiliation(s)
- Daniela da Fonseca Pacheco
- Department of Pharmacology, Institute of Biological Sciences, Federal University of Minas Gerais, Brazil
| | | | - Igor Dimitri Gama Duarte
- Department of Pharmacology, Institute of Biological Sciences, Federal University of Minas Gerais, Brazil
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Pacheco DDF, Pacheco CMDF, Duarte IDG. Peripheral antinociception induced by δ-opioid receptors activation, but not μ- or κ-, is mediated by Ca²⁺-activated Cl⁻ channels. Eur J Pharmacol 2011; 674:255-9. [PMID: 22134006 DOI: 10.1016/j.ejphar.2011.11.023] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2011] [Revised: 11/03/2011] [Accepted: 11/10/2011] [Indexed: 10/14/2022]
Abstract
Studies have demonstrated that the L-arginine/NO/cGMP pathway and the potassium and calcium channels are involved in the mechanisms underlying opioid receptor activation. As additional pathways may participate in the observed antinociceptive effects following opioid exposure, the aim of our study was to determine whether Ca(2+)-activated Cl(-) channels (CaCCs) are involved in peripheral antinociception induced by μ-, δ- and κ-opioid receptor activation. Hyperalgesia was induced by intraplantar injection of prostaglandin E(2) (PGE(2), 2 μg). Nociceptive thresholds to pressure (grams) were measured using an algesimetric apparatus 3h following injection. The μ-opioid receptor agonist morphine (200 μg), δ-opioid receptor agonist (+)-4-[(alphaR)-alpha-((2S,5R)-4-Allyl-2,5-dimethyl-1-piperazinyl)-3-methoxybenzyl]-N,N-diethylbenzamide (SNC80, 80 μg), κ-opioid receptor agonist bremazocine (50 μg), CaCCs blocker niflumic acid (8-64 μg), CaCCs blocker 5-Nitro-2-(3-phenylpropylamino) benzoic acid (NPPB, 32-128 μg), nitric oxide donor sodium nitroprusside (SNP, 500 μg) and cGMP exogenous analogs dibutyryl cGMP (db-cGMP, 100 μg) were also administered into the paw. The CaCCs blocker niflumic acid and NPPB partially reversed the peripheral antinociception induced by exposure to the SNC80 in a dose-dependent manner. In contrast, niflumic acid did not modify the antinociceptive effect observed following exposure to morphine or bremazocine. Additionally, the peripheral antinociception induced by the NO donor SNP or by db-cGMP was not inhibited by niflumic acid. These results provide evidence for the involvement of CaCCs in the peripheral antinociception induced by SNC80. CaCCs activation does not appear to be involved when μ- and κ-opioid receptors are activated. In addition, we did not observe a link between CaCCs and the L-arginine/NO/GMPc pathway.
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Affiliation(s)
- Daniela da Fonseca Pacheco
- Department of Pharmacology, Institute of Biological Sciences, UFMG, Av. Antônio Carlos, 6627, CEP: 31.270.100, Belo Horizonte, Brazil
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Reid B, Vieira AC, Cao L, Mannis MJ, Schwab IR, Zhao M. Specific ion fluxes generate cornea wound electric currents. Commun Integr Biol 2011; 4:462-5. [PMID: 21966572 DOI: 10.4161/cib.4.4.15545] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2011] [Accepted: 03/18/2011] [Indexed: 01/14/2023] Open
Abstract
The corneal epithelium generates a significant trans-epithelial potential (TEP) which aids in maintaining cornea water balance and transparency. Injury to the cornea causes a short circuit of the TEP at the wound. The TEP in the intact epithelium around the wound acts like a battery, powering significant ion flux and electric current at the wound. These circulating endogenous currents generate an electric field orientated towards the wound, with the wound the cathode. Many cell types, including human corneal epithelial cells and keratinocytes, migrate to the cathode at physiological electric field strengths. Indeed, the electric signal is a powerful stimulator of cell migration, which appears to override other cues such as chemotaxis and wound void. These wound fields also have a dynamic timecourse of change after wounding. It has been assumed that wound electric fields are produced by passive leakage of ions from damaged cells and tissue. Could these fields be actively maintained and regulated as an active wound response? What are the molecular, ionic and cellular mechanisms underlying the wound electric currents?
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Affiliation(s)
- Brian Reid
- Department of Dermatology; School of Medicine; Institute for Regenerative Cures; University of California; Davis, CA USA
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Johnson M, Allen L, Dobbs L. Characteristics of Cl- uptake in rat alveolar type I cells. Am J Physiol Lung Cell Mol Physiol 2009; 297:L816-27. [PMID: 19684200 DOI: 10.1152/ajplung.90466.2008] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Although Cl- transport in fetal lung is important for fluid secretion and normal lung development, the role of Cl- transport in adult lung is not well understood. In physiological studies, the cystic fibrosis transmembrane regulator (CFTR) plays a role in fluid absorption in the distal air spaces of adult lung, and alveolar type II cells cultured for 5 days have the capacity to transport Cl-. Although both alveolar type I and type II cells express CFTR, it has previously not been known whether type I cells transport Cl-. We studied Cl- uptake in isolated type I cells directly, using either radioisotopic tracers or halide-sensitive fluorescent indicators. By both methods, type I cells take up Cl-. In the presence of beta-adrenergic agonist stimulation, Cl- uptake can be inhibited by CFTR antagonists. Type I cells express both the Cl-/HCO3- anion exchanger AE2 and the voltage-gated Cl- channels CLC5 and CLC2. Inhibitors of AE2 also block Cl- uptake in type I cells. Together, these results demonstrate that type I cells are capable of Cl- uptake and suggest that the effects seen in whole lung studies establishing the importance of Cl- movement in alveolar fluid clearance may be, in part, the result of Cl- transport across type I cells.
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Affiliation(s)
- Meshell Johnson
- Department of Medicine, University of California, San Francisco, 3333 California St., Suite 150, Box 1245, San Francisco, CA 94118, USA.
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Leonhard-Marek S, Hempe J, Schroeder B, Breves G. Electrophysiological characterization of chloride secretion across the jejunum and colon of pigs as affected by age and weaning. J Comp Physiol B 2009; 179:883-96. [PMID: 19488761 DOI: 10.1007/s00360-009-0371-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2008] [Revised: 05/12/2009] [Accepted: 05/13/2009] [Indexed: 01/07/2023]
Abstract
Hypersecretion of chloride can cause diarrhea, a disease frequently occurring in young pigs, particularly around weaning. We investigated the contribution of different channels to intestinal Cl(-) secretion as influenced by age and weaning. Jejunal and colonic epithelia from 4-month-old pigs and 4-week-old piglets were incubated in Ussing chambers and stimulated by carbachol and forskolin. Changes in short-circuit currents were taken as measure of electrogenic net Cl(-) secretion. DIDS or NPPB served to inhibit Ca-activated Cl(-)-channels and outwardly rectifying Cl(-)-channels (ORCC) or cystic fibrosis transmembrane regulator (CFTR), respectively. Depolarizing the basolateral membrane allowed to examine the influence of K(+)-channels on Cl(-) secretion. Forskolin-stimulated Cl(-) secretion was mediated by CFTR. ORCC were not involved. Carbachol-induced Cl(-) secretion could be ascribed to an enhanced driving force due to the opening of K(+)-channels, whereas Ca-dependent Cl(-) channels seemed not to be involved. In jejunum, piglets showed higher Cl(-) secretion than pigs. Two days after weaning forskolin induced an I (sc) overshoot and a faster increase in G (t). In colon, Cl(-) secretion was neither influenced by age nor by weaning. The data suggest a disposition of porcine jejunum for a higher Cl(-) secretion in young and freshly weaned piglets, which might be a natural defense mechanism as well as a predisposing factor for diarrhea.
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Affiliation(s)
- Sabine Leonhard-Marek
- Department of Physiology, University of Veterinary Medicine Hannover, Bischofsholer Damm 15/102, 30173, Hannover, Germany.
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Ramteke VD, Tandan SK, Kumar D, Aruna Devi R, Shukla MK, Ravi Prakash V. Increased hyperalgesia by 5-nitro-2, 3-(phenylpropylamino)-benzoic acid (NPPB), a chloride channel blocker in crush injury-induced neuropathic pain in rats. Pharmacol Biochem Behav 2009; 91:417-22. [DOI: 10.1016/j.pbb.2008.08.017] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2008] [Revised: 07/26/2008] [Accepted: 08/12/2008] [Indexed: 01/22/2023]
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Edwards G, Weston AH. Section Review Cardiovascular & Renal: Recent advances in the pharmacology and therapeutic potential of potassium channel openers. Expert Opin Investig Drugs 2008. [DOI: 10.1517/13543784.5.11.1453] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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11
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Gill S, Gill R, Xie Y, Wicks D, Liang D. Development and Validation of HTS Flux Assay for Endogenously Expressed Chloride Channels in a CHO-K1 Cell Line. Assay Drug Dev Technol 2006; 4:65-71. [PMID: 16506890 DOI: 10.1089/adt.2006.4.65] [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] [Indexed: 11/13/2022] Open
Abstract
An atomic absorption spectroscopy-based detection system was employed to develop a new non-radioactive flux assay for chloride (Cl-) channels in a high throughput format. Cl- flux is assayed by measuring the extent to which Cl- precipitates an excess amount of silver ions (Ag+). A linear correlation was observed between theoretical and determined Cl- concentration with an r2 value of 0.996. The assay was found to be free from interference from various ions and proteins. The assay was used to study the physiology of endogenously expressed Cl- channels in a Chinese hamster ovary-K1 cell line. Cl- efflux was activated in response to an increased concentration of K+ (100 mM), Ca2+ (4 mM), and ionomycin (10 microM) as calcium ionophore. The efflux was also sensitive to pH as slightly higher efflux of Cl- was observed at an acidic pH of 3.2 in comparison to the neutral pH of 7.4. The Cl- efflux was inhibited by 100 microM 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS) and 500 microM 5-nitro-2-(3-phenylpropylamino) benzoate (NPPB) but not by tolbutamide, niflumic acid, or glybenclamide, indicating that the channel current is not sensitive to other cystic fibrosis transmembrane conductance regulator inhibitors. The 50% inhibitory concentration (IC50) values of DIDS at pH 7.4 and pH 3.2 were 17 microM and 19 microM, respectively. An IC50 of 26 microM was observed for NPPB. The assay had a Z' factor of 0.678.
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12
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Cruickshank SF, Baxter LM, Drummond RM. The Cl(-) channel blocker niflumic acid releases Ca(2+) from an intracellular store in rat pulmonary artery smooth muscle cells. Br J Pharmacol 2003; 140:1442-50. [PMID: 14623766 PMCID: PMC1574157 DOI: 10.1038/sj.bjp.0705571] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2003] [Revised: 09/16/2003] [Accepted: 10/07/2003] [Indexed: 11/08/2022] Open
Abstract
The effect of the Cl- channel blockers niflumic acid (NFA), 5-nitro-2-(3-phenylpropylamino)-benzoic acid (NPPB), 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS), and anthracene-9-carboxylic acid (A-9-C), on Ca2+ signalling in rat pulmonary artery smooth muscle cells was examined. Intracellular Ca2+ concentration ([Ca2+]i) was monitored with either fura-2 or fluo-4, and caffeine was used to activate the ryanodine receptor, thereby releasing Ca2+ from the sarcoplasmic reticulum (SR). NFA and NPPB significantly increased basal [Ca2+]i and attenuated the caffeine-induced increase in [Ca2+]i. These Cl- channel blockers also increased the half-time (t1/2) to peak for the caffeine-induced [Ca2+]i transient, and slowed the removal of Ca2+ from the cytosol following application of caffeine. Since DIDS and A-9-C were found to adversely affect fura-2 fluorescence, fluo-4 was used to monitor intracellular Ca2+ in studies involving these Cl- channel blockers. Both DIDS and A-9-C increased basal fluo-4 fluorescence, indicating an increase in intracellular Ca2+, and while DIDS had no significant effect on the t1/2 to peak for the caffeine-induced Ca2+ transient, it was significantly increased by A-9-C. In the absence of extracellular Ca2+, NFA significantly increased basal [Ca2+]i, suggesting that the release of Ca2+ from an intracellular store was responsible for the observed effect. Depleting the SR with the combination of caffeine and cyclopiazonic acid prevented the increase in basal [Ca2+]i induced by NFA. Additionally, incubating the cells with ryanodine also prevented the increase in basal [Ca2+]i induced by NFA. These data show that Cl- channel blockers have marked effects on Ca2+ signalling in pulmonary artery smooth muscle cells. Furthermore, examination of the NFA-induced increase in [Ca2+]i indicates that it is likely due to Ca2+ release from an intracellular store, most probably the SR.
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Affiliation(s)
- Stuart F Cruickshank
- Department of Physiology and Pharmacology, University of Strathclyde, 27 Taylor Street, Glasgow G4 ONR
| | - Lynne M Baxter
- Department of Physiology and Pharmacology, University of Strathclyde, 27 Taylor Street, Glasgow G4 ONR
| | - Robert M Drummond
- Department of Physiology and Pharmacology, University of Strathclyde, 27 Taylor Street, Glasgow G4 ONR
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Stummann TC, Poulsen JH, Hay-Schmidt A, Grunnet M, Klaerke DA, Rasmussen HB, Olesen SP, Jorgensen NK. Pharmacological investigation of the role of ion channels in salivary secretion. Pflugers Arch 2003; 446:78-87. [PMID: 12690466 DOI: 10.1007/s00424-002-0985-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2002] [Accepted: 10/29/2002] [Indexed: 01/01/2023]
Abstract
The role of K+ and Cl- channels in salivary secretion was investigated, with emphasis on the potential role of Ca2+ -activated K+ channels. Ligand saturation kinetic assays and autoradiography showed large-conductance (BK) K+ channels to be highly expressed in rat submandibular and parotid glands, whereas low-conductance (SK) K+ channels could not be detected. To investigate the role of K+ and Cl- channels in secretion, intact rabbit submandibular glands were vascularly perfused and secretion induced by 10 microM ACh. Secretion was inhibited by 34+/-3% following perfusion with the general K+ channel inhibitor Ba2+ (5 mM), whereas organic inhibitors of BK (200 nM paxilline) or intermediate-conductance (IK) K+ channels (5 microM clotrimazole) had no effect. Secretion was strongly influenced by Cl- channel inhibitors, as 100 microM 5-nitro-2-(3-phenylpropylamino)benzoate (NPPB) completely abolished, while 10 microM NPPB, 20 microM NS1652 and 20 microM NS3623 reduced secretion by 34+/-3%, 23+/-3% and 59+/-4%, respectively. In conclusion, although high expression levels of BK channels were demonstrated, pharmacological tools failed to demonstrate any role for BK, IK or SK channels in salivary secretion in the rabbit submandibular gland. Other types of K+ channel, however, and particularly Cl- channels, are essential for ACh-induced salivary secretion.
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Affiliation(s)
- Tina C Stummann
- Department of Medical Physiology, The Panum Institute, University of Copenhagen, Blegdamsvej 3, 2200 Copenhagen N, Denmark
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Lamas JA, Reboreda A, Codesido V. Ionic basis of the resting membrane potential in cultured rat sympathetic neurons. Neuroreport 2002; 13:585-91. [PMID: 11973451 DOI: 10.1097/00001756-200204160-00010] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The conductances which determine the resting membrane potential of rat superior cervical ganglia (SCG) neurons were investigated using perforated voltage- and current-clamp whole-cell techniques. The resting potential of SCG cells varied from -47 to -80 mV (-58.3 +/- 0.8 mV, n = 55). Blockade of M and h currents induced a depolarisation (7.4 +/- 0.7 mV, n = 22) and a hyperpolarisation (7.2 +/- 0.7 mV, n = 20) respectively; however, no correlation between the amplitude of these currents and the resting potential was found. The inhibition of the Na/K pump also induced membrane depolarisation (3.2 +/- 0.2 mV, n = 8). Inhibition of voltage-gated currents unmasked a voltage-independent resting conductance reversing at -50 mV. The reversal potential of the voltage-independent conductance, which included the electrogenic contribution of the Na/K pump, was strongly correlated with the resting potential (R = 0.87, p < 0.0001, n = 30). Ionic substitution experiments confirmed the existence of a voltage-independent conductance (leakage) with four components, a main potassium conductance, two minor sodium and chloride conductances and a small contribution of the Na/K pump. It is concluded that the resting potential of SCG cells strongly depends on the reversal potential of the voltage-independent conductance, with voltage-activated M and h currents playing a prominent stabilising role.
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Affiliation(s)
- J Antonio Lamas
- Section of Physiology, Department of Functional Biology, Faculty of Sciences, University of Vigo, Lagoas-Marcosende, 36200, Spain
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Dai Y, Zhang JH. Manipulation of chloride flux affects histamine-induced contraction in rabbit basilar artery. Am J Physiol Heart Circ Physiol 2002; 282:H1427-36. [PMID: 11893580 DOI: 10.1152/ajpheart.00837.2001] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cl(-) efflux induces depolarization and contraction of smooth muscle cells. This study was undertaken to explore the role of Cl(-) flux in histamine-induced contraction in the rabbit basilar artery. Male New Zealand White rabbits (n = 16) weighing 1.8-2.5 kg were euthanized by an overdose of pentobarbital sodium. The basilar arteries were removed for isometric tension recording. Histamine produced a concentration-dependent contraction that was attenuated by the H(1) receptor antagonist chlorpheniramine (10(-8) M) but not by the H(2) receptor antagonist cimetidine (3 x 10(-6) M) in normal Cl(-) Krebs-Henseleit bicarbonate solution (123 mM Cl(-)). The histamine-induced contraction was reduced by the following manipulations: 1) inhibition of Na(+)-K(+)-2Cl(-) cotransporter with bumetanide (3 x 10(-5) and 10(-4) M), 2) bicarbonate-free HEPES solution to disable Cl(-)/HCO exchanger, and 3) blockade of Cl(-) channels with the use of niflumic acid, 5-nitro-2-(3-phenylpropylamino) benzoic acid, and indoleacetic acid 94 R-(+)-methylindazone. In addition, substitution of extracellular Cl(-) (10 mM) with methanesulfonate acid (113 mM) transiently enhanced histamine-induced contraction. Manipulation of Cl(-) flux affects histamine-induced contraction in the rabbit basilar artery.
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Affiliation(s)
- Yun Dai
- Department of Neurosurgery, University of Mississippi Medical Center, Jackson, Mississippi 39216, USA
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Abstract
Cl- efflux induces depolarization and contraction of smooth muscle cells. This study was undertaken to explore the role of Cl- channels in endothelin-1 (ET-1)-induced contraction in rabbit basilar artery. Male New Zealand White rabbits (n = 26), weighing 1.8-2.5 kg, were euthanized by an overdose of pentobarbital. The basilar arteries were removed for isometric tension recording. ET-1 produced a concentration-dependent contraction of the rabbit basilar artery in the normal Cl- Krebs-Henseleit bicarbonate buffer (123 mM Cl-). The ET-1-induced contraction was reduced by the following manipulations: 1) inhibition of Na+-K+-2Cl- cotransporter with bumetanide (3 x 10(-5) and 10(-4) M), 2) bicarbonate-free solution to disable Cl-/HCO exchanger, and 3) preincubation of rings with the Cl- channel blockers niflumic acid, 5-nitro-2-(3-phenylpropylamino)benzoic acid, and indanyloxyacetic acid 94. The ET-1-induced contraction was enhanced by substitution of extracellular Cl- (10 mM) with methanesulfonic acid (113 mM). Cl- channels are involved in ET-1-induced contraction in the rabbit basilar artery.
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Affiliation(s)
- Y Dai
- Department of Neurosurgery, University of Mississippi Medical Center, Jackson, Mississippi 39216, USA
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Zhang Y, Miller DV, Paterson WG. Opposing roles of K(+) and Cl(-) channels in maintenance of opossum lower esophageal sphincter tone. Am J Physiol Gastrointest Liver Physiol 2000; 279:G1226-34. [PMID: 11093945 DOI: 10.1152/ajpgi.2000.279.6.g1226] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The ionic basis underlying the maintenance of myogenic tone of lower esophageal sphincter circular muscle (LES) was investigated in opossum with the use of standard isometric tension and conventional intracellular microelectrode recordings in vitro. In tension recording studies, nifedipine (1 microM) reduced basal tone to 27.7 +/- 3.8% of control. The K(+) channel blockers tetraethylammonium (TEA, 2 mM), charybdotoxin (100 nM), and 4-aminopyridine (4-AP, 2 mM) enhanced resting tone, whereas apamin and glibenclamide were without affect. Cl(-) channel blockers DIDS (500 microM) and 5-nitro-2-(3-phenylpropylamino)-benzoic acid (500 microM), as well as niflumic acid (0.1-300 microM), decreased basal tone, but tamoxifen was without effect. Intracellular microelectrode recordings revealed ongoing, spontaneous, spike-like action potentials (APs). Nifedipine abolished APs and depolarized resting membrane potential (RMP). Both TEA and 4-AP significantly depolarized RMP and augmented APs, whereas niflumic acid dose-dependently hyperpolarized RMP and abolished APs. These data suggest that, in the opossum, basal tone is associated with continuous APs and that K(+) and Ca(2+)-activated Cl(-) channels have important opposing roles in the genesis of LES tone.
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Affiliation(s)
- Y Zhang
- Gastrointestinal Diseases Research Unit and Departments of Medicine and Physiology, Queen's University, Kingston, Ontario, Canada K7L 5G2
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Holt JC, Pantoja AM, Athas GB, Guth PS. A role for chloride in the hyperpolarizing effect of acetylcholine in isolated frog vestibular hair cells. Hear Res 2000; 146:17-27. [PMID: 10913880 DOI: 10.1016/s0378-5955(00)00092-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Acetylcholine (ACh) is the dominant transmitter released from inner ear efferent neurons. In frog vestibular organs, these efferent neurons synapse exclusively with type II hair cells. Hair cells isolated from the frog saccule hyperpolarize following the application of 50 microM ACh, thereby demonstrating the presence of an ACh receptor. A role for Cl(-) in the response of hair cell-bearing organs to efferent nerve activation or ACh application was suggested some years ago. Perfusion with solutions in which most of the Cl(-) was replaced by large impermeant anions decreased the cholinergic inhibition of afferent firing in the cat and turtle cochleas, and frog semicircular canal. Our previous work in the intact organ demonstrated that substitution of large impermeant anions for Cl(-) or use of Cl(-) channel blockers reduced the effect of ACh on saccular afferent firing. Using the perforated-patch clamping technique, replacement of Cl(-) by methanesulfonate, iodide, nitrate, or thiocyanate attenuated the hyperpolarizing response to ACh in hair cells isolated from the frog saccule. The chloride channel blockers picrotoxin and 4,4'-dinitrostilbene-2,2'-disulfonic acid were also tested and found to inhibit the ACh response. Thus, the present work demonstrates that the effects of Cl(-) substitutions or Cl(-) channel blockers on the ACh response in the intact saccule can be explained completely by effects on the hair cell. Evidence is also presented for the presence of the messenger RNA for a calcium-dependent chloride channel in all hair cells but especially saccular hair cells. This channel may be involved in the response to ACh. The precise role for chloride in this response, whether as a distinct ion current, as a transported ion, or as a permissive ion for other components, is discussed.
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Affiliation(s)
- J C Holt
- Department of Pharmacology, Tulane University School of Medicine, New Orleans, LA 70112, USA
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Min SA, Stapleton MP, Tabrizchi R. Influence of chloride ions on alpha1-adrenoceptor mediated contraction and Ca2+ influx in rat caudal artery. Life Sci 1999; 64:1631-41. [PMID: 10328523 DOI: 10.1016/s0024-3205(99)00100-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The objective of the present investigation was to compare and contrast the effects of 8-bromoguanosine 3':5'-cyclic monophosphate (8-Bromo-cyclic GMP), an analogue of guanosine 3':5'-cyclic monophosphate, felodipine, a dihydropyridine Ca2+ channel antagonist, and 5-nitro-2-(3-phenylpropylamino) benzoic acid (NPPB), a putative chloride channel antagonist on alpha1-adrenoceptor mediated contraction and Ca2+ influx in rat caudal artery, in normal physiological salt solution and in chloride-free solution. Isometric contractions and 45Ca2+ influx were measured in isolated rat caudal arterial rings. Phenylephrine induced concentration-dependent contractions were inhibited by 8-Bromo-cyclic GMP (10 microM), felodipine (10 nM) and NPPB (3.0 microM). Removal of chloride ions also impaired phenylephrine-induced contractions. In chloride-free buffer, phenylephrine-induced contractions were partially inhibited by the presence of 8-Bromo-cGMP or felodipine, while NPPB had no effect. Phenylephrine induced 45Ca2+ influx was inhibited by the presence of 8-Bromo-cyclic GMP, felodipine and NPPB. Moreover, removal of chloride ions also inhibited phenylephrine-induced 45Ca2+ influx. The results of our study demonstrate that in the rat caudal artery the inhibitory effects of 8-Bromo-cyclic GMP, felodipine and NPPB, are mediated through a reduction of Ca2+ influx. In addition, chloride ions, in part, play a role in alpha1-adrenoceptor-mediated Ca2+ influx. However, the influence of removal of chloride ions on phenylephrine stimulated contraction is limited. Moreover, 8-Bromo-cyclic GMP and felodipine, but not NPBB, impair phenylephrine-induced contractions in the absence of chloride ions.
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Affiliation(s)
- S A Min
- Division of Basic Medical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John's, Canada
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Doughty JM, Miller AL, Langton PD. Non-specificity of chloride channel blockers in rat cerebral arteries: block of the L-type calcium channel. J Physiol 1998; 507 ( Pt 2):433-9. [PMID: 9518703 PMCID: PMC2230802 DOI: 10.1111/j.1469-7793.1998.433bt.x] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
1. The effects of chloride channel blockers on pressure-induced constriction, K(+)-induced force, and whole-cell calcium channel currents were tested in rat cerebral arteries using isobaric and isometric myography, and patch clamp. 2. Under isobaric conditions at 75 mmHg, 5-nitro-2-(3-phenylpropylamino)benzoic acid (NPPB), a chloride channel blocker, reversibly depressed the myogenic constriction with an IC50 of 32.8 +/- 0.52 microM (mean +/- S.E.M., n = 5). Blockers of Ca(2+)-activated chloride channels, flufenamic acid (100 microM) and 9-anthracene chloride (9-AC; 1 mM), and the cystic fibrosis transmembrane conductance regulator (CFTR) Cl- channel blocker, glibenclamide (100 microM), were without effect in this tissue (n = 3). 3. Under isobaric conditions at 20 mmHg, 37 degrees C, raising [K+]o to 45 mM induced a constriction which was unaffected by 100 microM NPPB (n = 4). In contrast, at 75 mmHg and 18-21 degrees C, 100 microM NPPB completely and reversibly blocked a 45 mM K(+)-induced constriction (n = 3). 4. Under isometric conditions, NPPB reversibly depressed a 45 mM K(+)-induced force with an IC50 of 10.0 +/- 0.76 microM (mean +/- S.E.M., n = 5). Indanyloxyacetic acid 94 (IAA-94), another chloride channel blocker, depressed the K(+)-induced force with an IC50 of 17.0 +/- 1.2 microM (mean +/- S.E.M., n = 4). 5. Using whole-cell patch clamp, 100 microM NPPB or 200 microM IAA-94 blocked calcium channel currents carried by 10 mM Ba2+ by 79.1 +/- 1.7 and 39.8 +/- 7.0%, respectively (mean +/- S.E.M., n = 6). 6. In summary, chloride channel blockers depress calcium channel currents in rat cerebral arteries, which could contribute to a reduction in myogenic contraction.
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Affiliation(s)
- J M Doughty
- Department of Physiology, University of Bristol, UK
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Zygmunt PM, Högestätt ED, Waldeck K, Edwards G, Kirkup AJ, Weston AH. Studies on the effects of anandamide in rat hepatic artery. Br J Pharmacol 1997; 122:1679-86. [PMID: 9422814 PMCID: PMC1565127 DOI: 10.1038/sj.bjp.0701601] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
1. The effects of anandamide on K+ currents and membrane potential have been examined in freshly-isolated smooth muscle cells from rat hepatic artery and the results compared with the effects of this arachidonic acid derivative on tension and membrane potential changes in segments of whole artery. 2. In the presence of 0.3 mM L-NOARG and 10 microM indomethacin, anandamide (0.1-100 microM) and endothelium-derived hyperpolarizing factor (EDHF; liberated by acetylcholine, 0.01-10 microM) each relaxed endothelium-intact segments of hepatic artery precontracted with phenylephrine. These effects of anandamide, but not those of EDHF, were antagonized by the cannabinoid receptor antagonist, SR141716A (3 microM). 3. The relaxant effects of anandamide were unaffected by a toxin combination (apamin plus charybdotoxin, each 0.3 microM) which abolishes EDHF relaxations and were essentially unchanged in endothelium-denuded arteries. The relaxant effects of anandamide in endothelium-intact arteries were significantly reduced in a physiological salt solution containing 30 mM KCl and abolished when the K+ concentration was raised to 60 mM. 4. Anandamide (10 microM), acetylcholine (1 microM, via release of EDHF) and levcromakalim (10 microM) each markedly hyperpolarized the membrane potential of the smooth muscle cells of endothelium-intact arteries. However, when the endothelium was removed, the hyperpolarizing effects of both anandamide (10 microM) and acetylcholine were essentially abolished whereas those of levcromakalim (10 microM) were unaffected. 5. Under voltage-clamp conditions, anandamide (10 microM) abolished spontaneous transient outward currents (STOCs) in freshly-isolated single hepatic artery cells held at 0 mV but had no effect on the holding current at this potential. In current-clamp mode, the spontaneous hyperpolarizing potentials which corresponded to the STOCs were abolished with no significant change in basal membrane potential. 6. Anandamide (10 microM) abolished the iberiotoxin-sensitive K+ current (IBK(Ca)) produced by caffeine and the corresponding hyperpolarizations generated by this xanthine derivative in current-clamp mode. In contrast, anandamide had no effect on IBK(Ca) generated on exposure to NS1619 (30 microM). 7. It was concluded that anandamide is not EDHF in the rat hepatic artery. Anandamide-induced hyperpolarization is exerted indirectly and requires the presence of the endothelium. Anandamide also acts on the smooth muscle cells to inhibit processes which require functional intracellular calcium stores. This direct action seems more important than membrane hyperpolarization in relaxing phenylephrine-contracted vessels.
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Affiliation(s)
- P M Zygmunt
- School of Biological Sciences, University of Manchester
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Pantoja AM, Holt JC, Guth PS. A role for chloride in the suppressive effect of acetylcholine on afferent vestibular activity. Hear Res 1997; 112:21-32. [PMID: 9367226 DOI: 10.1016/s0378-5955(97)00101-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Afferents of the frog semicircular canal (SCC) respond to acetylcholine (ACh) application (0.3-1.0 mM) with a facilitation of their activity while frog saccular afferents respond with suppression (Guth et al., 1994). All recordings are of resting (i.e., non-stimulated) multiunit activity as previously reported (Guth et al., 1994). Substitution of 80% of external chloride (Cl-) by large, poorly permeant anions of different structures (isethionate, methanesulfonate, methylsulfate, and gluconate) reduced the suppressive effect of ACh in the frog saccular afferents. This substitution did not affect the facilitatory response of SCC afferents to ACh. Chloride channel blockers were also used to test further whether Cl- is involved in the ACh suppressive effect. These included: niflumic and flufenamic acids, picrotoxin, 5-nitro-2-(-3-phenylpropylamino)benzoic acid (NPPB), and 4,4'-dinitrostilbene-2,2'-disulfonic acid (DNDS). As with the Cl- substitutions, all of these agents reduced the suppressive response to ACh in the saccule, but not the facilitatory response seen in the SCC. The suppressive effect of ACh on saccular afferents is considered to be due to activation of a nicotinic-like receptor (Guth et al., 1994; Guth and Norris, 1996). Taking into account the effects of both Cl- substitutions and Cl- channel blockers, we conclude that changes in Cl- availability influence the suppressive effect of ACh and that therefore Cl- may be involved in this effect.
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Affiliation(s)
- A M Pantoja
- Departamento de Farmacologia, Universidad del Valle, Cali, Colombia
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Kirkup AJ, Edwards G, Green ME, Miller M, Walker SD, Weston AH. Modulation of membrane currents and mechanical activity by niflumic acid in rat vascular smooth muscle. Eur J Pharmacol 1996; 317:165-74. [PMID: 8982733 DOI: 10.1016/s0014-2999(96)00713-3] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The effects of niflumic acid on whole-cell membrane currents and mechanical activity were examined in the rat portal vein. In freshly dispersed portal vein cells clamped at -60 mV in caesium (Cs+)-containing solutions, niflumic acid (1-100 microM) inhibited calcium (Ca2+)-activated chloride currents (IC1(Ca)) induced by caffeine (10 mM) and by noradrenaline (10 microM). In a potassium (K+)-containing solution and at a holding potential of - 10 mV, niflumic acid (10-100 microM) induced an outward K+ current (IK(ATP)) which was sensitive to glibenclamide (10-30 microM). At concentrations < 30 microM and at a holding potential of -2 mV, niflumic acid had no effect on the magnitude of the caffeine- or noradrenaline-stimulated current (IBK(Ca)) carried by the large conductance, Ca(2+)-sensitive K+ channel (BKCa). However, at a concentration of 100 microM, niflumic acid significantly inhibited IBK(Ca)) evoked by caffeine (10 mM) but not by NS1619 (1-(2'-hydroxy-5'-trifluoromethylphenyl)-5-trifluoromethyl-2(3 H) benzimidazolone; 20 microM). In Cs(+)-containing solutions, niflumic acid (10-100 microM) did not inhibit voltage-sensitive Ca2+ currents. In intact portal veins, niflumic acid (1-300 microM) inhibited spontaneous mechanical activity, an action which was partially antagonised by glibenclamide (1-10 microM), and contractions produced by noradrenaline (10 microM), an effect which was glibenclamide-insensitive. It is concluded that inhibition of ICl(Ca) and stimulation of IK(ATP) both contribute to the mechano-inhibitory actions of niflumic acid in the rat portal vein.
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Affiliation(s)
- A J Kirkup
- School of Biological Sciences, University of Manchester, UK
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