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Martinez-Pinna J, Soriano S, Tudurí E, Nadal A, de Castro F. A Calcium-Dependent Chloride Current Increases Repetitive Firing in Mouse Sympathetic Neurons. Front Physiol 2018; 9:508. [PMID: 29867553 PMCID: PMC5960682 DOI: 10.3389/fphys.2018.00508] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Accepted: 04/20/2018] [Indexed: 11/18/2022] Open
Abstract
Ca2+-activated ion channels shape membrane excitability in response to elevations in intracellular Ca2+. The most extensively studied Ca2+-sensitive ion channels are Ca2+-activated K+ channels, whereas the physiological importance of Ca2+-activated Cl- channels has been poorly studied. Here we show that a Ca2+-activated Cl- currents (CaCCs) modulate repetitive firing in mouse sympathetic ganglion cells. Electrophysiological recording of mouse sympathetic neurons in an in vitro preparation of the superior cervical ganglion (SCG) identifies neurons with two different firing patterns in response to long depolarizing current pulses (1 s). Neurons classified as phasic (Ph) made up 67% of the cell population whilst the remainders were tonic (T). When a high frequency train of spikes was induced by intracellular current injection, SCG sympathetic neurons reached an afterpotential mainly dependent on the ratio of activation of two Ca2+-dependent currents: the K+ [IK(Ca)] and CaCC. When the IK(Ca) was larger, an afterhyperpolarization was the predominant afterpotential but when the CaCC was larger, an afterdepolarization (ADP) was predominant. These afterpotentials can be observed after a single action potential (AP). Ph and T neurons had similar ADPs and hence, the CaCC does not seem to determine the firing pattern (Ph or T) of these neurons. However, inhibition of Ca2+-activated Cl- channels with anthracene-9'-carboxylic acid (9AC) selectively inhibits the ADP, reducing the firing frequency and the instantaneous frequency without affecting the characteristics of single- or first-spike firing of both Ph and T neurons. Furthermore, we found that the CaCC underlying the ADP was significantly larger in SCG neurons from males than from females. Furthermore, the CaCC ANO1/TMEM16A was more strongly expressed in male than in female SCGs. Blocking ADPs with 9AC did not modify synaptic transmission in either Ph or T neurons. We conclude that the CaCC responsible for ADPs increases repetitive firing in both Ph and T neurons, and it is more relevant in male mouse sympathetic ganglion neurons.
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Affiliation(s)
- Juan Martinez-Pinna
- Departamento de Fisiología, Genética y Microbiología, Universidad de Alicante, Alicante, Spain
| | - Sergi Soriano
- Departamento de Fisiología, Genética y Microbiología, Universidad de Alicante, Alicante, Spain
| | - Eva Tudurí
- Institute of Bioengineering and CIBER de Diabetes y Enfermedades Metabólicas Asociadas, Miguel Hernández University of Elche, Elche, Spain
| | - Angel Nadal
- Institute of Bioengineering and CIBER de Diabetes y Enfermedades Metabólicas Asociadas, Miguel Hernández University of Elche, Elche, Spain
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Hannigan KI, Griffin CS, Large RJ, Sergeant GP, Hollywood MA, McHale NG, Thornbury KD. The role of Ca 2+-activated Cl - current in tone generation in the rabbit corpus cavernosum. Am J Physiol Cell Physiol 2017; 313:C475-C486. [PMID: 28835432 DOI: 10.1152/ajpcell.00025.2017] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Revised: 08/03/2017] [Accepted: 08/09/2017] [Indexed: 11/22/2022]
Abstract
Rabbit corpus cavernosum smooth muscle (RCCSM) cells express ion channels that produce Ca2+-activated Cl- (IClCa) current, but low sensitivity to conventional antagonists has made its role in tone generation difficult to evaluate. We have reexamined this question using two new generation IClCa blockers, T16Ainh-A01 and CaCCinh-A01. Isolated RCCSM cells were studied using the perforated patch method. Current-voltage protocols revealed that both L-type Ca2+ current and IClCa T16Ainh-A01 and CaCCinh-A01 (10 μM) reduced IClCa by ~85%, while 30 μM abolished it. L-type Ca2+ current was unaffected by 10 μM CaCCinh-A01 but was reduced by 50% at 30 μM CaCCinh-A01, 46% at 10 μM T16Ainh-A01, and 78% at 30 μM T16Ainh-A01. Both drugs reduced spontaneous isometric tension in RCCSM strips, by 60-70% at 10 μM and >90% at 30 μM. Phenylephrine (PE)-enhanced tension was also reduced (ED50 = 3 μM, CaCCinh-A01; 14 μM, T16Ainh-A01). CaCCinh-A01 at 10 μM had little effect on 60 mM KCl contractures, though they were reduced by 30 μM CaCCinh-A01 and T16Ainh-A01 (10 μM and 30 μM) consistent with their effects on L-type Ca2+ current. Both drugs also reversed the stimulatory effect of PE on intracellular Ca2+ waves, studied with laser scanning confocal microscopy in isolated RCCSM cells. In conclusion, although both drugs were effective blockers of IClCa, the effect of T16Ainh-A01 on L-type Ca2+ current precludes its use for evaluating the role of IClCa in tone generation. However, 10 μM CaCCinh-A01 selectively blocked IClCa versus L-type Ca2+ current and reduced spontaneous and PE-induced tone, suggesting that IClCa is important in maintaining penile detumescence.
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Affiliation(s)
- Karen I Hannigan
- Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Ireland
| | - Caoimhin S Griffin
- Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Ireland
| | - Roddy J Large
- Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Ireland
| | - Gerard P Sergeant
- Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Ireland
| | - Mark A Hollywood
- Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Ireland
| | - Noel G McHale
- Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Ireland
| | - Keith D Thornbury
- Smooth Muscle Research Centre, Dundalk Institute of Technology, Dundalk, Ireland
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Dam VS, Boedtkjer DMB, Aalkjaer C, Matchkov V. The bestrophin- and TMEM16A-associated Ca(2+)- activated Cl(–) channels in vascular smooth muscles. Channels (Austin) 2015; 8:361-9. [PMID: 25478625 PMCID: PMC4203738 DOI: 10.4161/chan.29531] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The presence of Ca2+-activated Cl– currents (ICl(Ca)) in vascular smooth muscle cells (VSMCs) is well established. ICl(Ca) are supposedly important for arterial contraction by linking changes in [Ca2+]i and membrane depolarization. Bestrophins and some members of the TMEM16 protein family were recently associated with ICl(Ca). Two distinct ICl(Ca) are characterized in VSMCs; the cGMP-dependent ICl(Ca) dependent upon bestrophin expression and the ‘classical’ Ca2+-activated Cl– current, which is bestrophin-independent. Interestingly, TMEM16A is essential for both the cGMP-dependent and the classical ICl(Ca). Furthermore, TMEM16A has a role in arterial contraction while bestrophins do not. TMEM16A’s role in the contractile response cannot be explained however only by a simple suppression of the depolarization by Cl– channels. It is suggested that TMEM16A expression modulates voltage-gated Ca2+ influx in a voltage-independent manner and recent studies also demonstrate a complex role of TMEM16A in modulating other membrane proteins.
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Contribution of Ca²⁺-dependent Cl⁻ channels to norepinephrine-induced contraction of femoral artery is replaced by increasing EDCF contribution during ageing. BIOMED RESEARCH INTERNATIONAL 2014; 2014:289361. [PMID: 24707479 PMCID: PMC3953470 DOI: 10.1155/2014/289361] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Accepted: 01/16/2014] [Indexed: 12/04/2022]
Abstract
The activation of Ca2+-dependent Cl− channels during norepinephrine-induced contraction of vascular smooth muscle was suggested to depolarize cell membrane and to increase Ca2+ entry. Hypertension and ageing are associated with altered Ca2+ handling including possible activation of Ca2+-dependent Cl− channels. Our study was aimed to determine Ca2+-dependent Cl− channels contribution to norepinephrine-induced contraction during hypertension and ageing. Norepinephrine-induced concentration-response curves of femoral arteries from 6- and 12-month-old spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats were recorded using wire myograph. Pretreatment with Ca2+-dependent Cl- channel inhibitor indanyloxyacetic acid 94 [R(+)-IAA-94](IAA) attenuated norepinephrine-induced contraction in all groups, but relatively more in WKY than SHR arteries. The attenuation of norepinephrine-induced contraction after Ca2+-dependent Cl− channels blockade was partially reduced in 12-month-old WKY rats, but substantially diminished in 12-month-old SHR. IAA effect was enhanced after NO synthase inhibition but decreased by ageing. In 20-month-old WKY rats norepinephrine-induced contraction was not affected by IAA but was almost abolished after cyclooxygenase inhibition by indomethacin or niflumic acid. In conclusion, contribution of Ca2+-dependent Cl− channels to norepinephrine-induced contraction diminished with age, hypertension development, and/or NO synthesis inhibition. Ca2+-dependent Cl− channels are important for maintenance of normal vascular tone while their inactivation/closing might be a pathological mechanism.
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Abstract
To succeed in fertilization, spermatozoa must decode environmental cues which require a set of ion channels. Recent findings have revealed that K(+) and Cl(-) channels participate in some of the main sperm functions. This work reviews the evidence indicating the involvement of K(+) and Cl(-) channels in motility, maturation, and the acrosome reaction, and the advancement in identifying their molecular identity and modes of regulation. Improving our insight on how these channels operate will strengthen our ability to surmount some infertility problems, improve animal breeding, preserve biodiversity, and develop selective and secure male contraceptives.
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Matchkov VV, Secher Dam V, Bødtkjer DMB, Aalkjær C. Transport and Function of Chloride in Vascular Smooth Muscles. J Vasc Res 2013; 50:69-87. [DOI: 10.1159/000345242] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2012] [Accepted: 10/16/2012] [Indexed: 12/12/2022] Open
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Orta G, Ferreira G, José O, Treviño CL, Beltrán C, Darszon A. Human spermatozoa possess a calcium-dependent chloride channel that may participate in the acrosomal reaction. J Physiol 2012; 590:2659-75. [PMID: 22473777 DOI: 10.1113/jphysiol.2011.224485] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Motility, maturation and the acrosome reaction (AR) are fundamental functions of mammalian spermatozoa. While travelling through the female reproductive tract, spermatozoa must mature through a process named capacitation, so that they can reach the egg and undergo the AR, an exocytotic event necessary to fertilize the egg. Though Cl⁻ is important for sperm capacitation and for the AR, not much is known about the molecular identity of the Cl⁻ transporters involved in these processes.We implemented a modified perforated patch-clamp strategy to obtain whole cell recordings sealing on the head of mature human spermatozoa.Our whole cell recordings revealed the presence of a Ca²⁺-dependent Cl⁻ current. The biophysical characteristics of this current and its sensitivity to niflumic acid (NFA) and 4,4-diisothiocyano-2,2-stilbene disulphonic acid (DIDIS) are consistent with those displayed by the Ca²⁺-dependent Cl⁻ channel from the anoctamin family (TMEM16). Whole cell patch clamp recordings in the cytoplasmic droplet of human spermatozoa corroborated the presence of these currents, which were sensitive to NFA and to a small molecule TMEM16A inhibitor (TMEM16Ainh, an aminophenylthiazole). Importantly, the human sperm AR induced by a recombinant human glycoprotein from the zona pellucida, rhZP3, displayed a similar sensitivity to NFA, DIDS and TMEM16Ainh as the sperm Ca²⁺-dependent Cl⁻ currents. Our findings indicate the presence of Ca²⁺-dependent Cl⁻ currents in human spermatozoa, that TMEM16A may contribute to these currents and also that sperm Ca²⁺-dependent Cl⁻ currents may participate in the rhZP3-induced AR.
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Affiliation(s)
- Gerardo Orta
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, CP 62210, México
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Sones WR, Davis AJ, Leblanc N, Greenwood IA. Cholesterol depletion alters amplitude and pharmacology of vascular calcium-activated chloride channels. Cardiovasc Res 2010; 87:476-84. [PMID: 20172862 DOI: 10.1093/cvr/cvq057] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
AIMS Calcium-activated chloride channels (CACCs) share common pharmacological properties with Kcnma1-encoded large conductance K(+) channels (BK(Ca) or K(Ca)1.1) and it has been suggested that they may co-exist in a macromolecular complex. As K(Ca)1.1 channels are known to localize to cholesterol and caveolin-rich lipid rafts (caveolae), the present study investigated whether Ca(2+)-sensitive Cl(-) currents in vascular myocytes were affected by the cholesterol depleting agent methyl-beta-cyclodextrin (M-betaCD). METHODS AND RESULTS Calcium-activated chloride and potassium currents were recorded from single murine portal vein myocytes in whole cell voltage clamp. Western blot was undertaken following sucrose gradient ultracentrifugation using protein lysates from whole portal veins. Ca(2+)-activated Cl(-) currents were augmented by 3 mg mL(-1) M-betaCD with a rapid time course (t(0.5) = 1.8 min). M-betaCD had no effect on the bi-modal response to niflumic acid or anthracene-9-carboxylate but completely removed the inhibitory effects of the K(Ca)1.1 blockers, paxilline and tamoxifen, as well as the stimulatory effect of the K(Ca)1.1 activator NS1619. Discontinuous sucrose density gradients followed by western blot analysis revealed that the position of lipid raft markers caveolin and flotillin-2 was altered by 15 min application of 3 mg mL(-1) M-betaCD. The position of K(Ca)1.1 and the newly identified candidate for CACCs, TMEM16A, was also affected by M-betaCD. CONCLUSION These data reveal that CACC properties are influenced by lipid raft integrity.
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Affiliation(s)
- William R Sones
- Division of Basic Medical Sciences, St George's, University of London, London SW17 0RE, UK
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Sones WR, Leblanc N, Greenwood IA. Inhibition of vascular calcium-gated chloride currents by blockers of KCa1.1, but not by modulators of KCa2.1 or KCa2.3 channels. Br J Pharmacol 2009; 158:521-31. [PMID: 19645713 DOI: 10.1111/j.1476-5381.2009.00332.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND AND PURPOSE Recent pharmacological studies have proposed there is a high degree of similarity between calcium-activated Cl(-) channels (CaCCs) and large conductance, calcium-gated K(+) channels (K(Ca)1.1). The goal of the present study was to ascertain whether blockers of K(Ca)1.1 inhibited calcium-activated Cl(-) currents (I(ClCa)) and if the pharmacological overlap between K(Ca)1.1 and CaCCs extends to intermediate and small conductance, calcium-activated K(+) channels. EXPERIMENTAL APPROACHES Whole-cell Cl(-) and K(+) currents were recorded from murine portal vein myocytes using the whole-cell variant of the patch clamp technique. CaCC currents were evoked by pipette solutions containing 500 nM free [Ca(2+)]. KEY RESULTS The selective K(Ca)1.1 blocker paxilline (1 microM) inhibited I(ClCa) by approximately 90%, whereas penitrem A (1 microM) and iberiotoxin (100 and 300 nM) reduced the amplitude of I(ClCa) by approximately 20%, as well as slowing channel deactivation. Paxilline also abolished the stimulatory effect of niflumic acid on the CaCC. In contrast, an antibody against the Ca(2+)-binding domain of murine K(Ca)1.1 had no effect on I(ClCa) while inhibiting spontaneous K(Ca)1.1 currents. Structurally different modulators of small and intermediate conductance calcium-activated K(+) channels (K(Ca)2.1 and K(Ca)2.3), namely 1-EBIO, (100 microM); NS309, (1 microM); TRAM-34, (10 microM); UCL 1684, (1 microM) had no effect on I(ClCa). CONCLUSIONS AND IMPLICATIONS These data show that the selective K(Ca)1.1 blockers also reduce I(ClCa) considerably. However, the pharmacological overlap that exists between CaCCs and K(Ca)1.1 does not extend to the calcium-binding domain or to other calcium-gated K(+) channels.
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Affiliation(s)
- W R Sones
- Division of Basic Medical Sciences, St George's, University of London, London, UK
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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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Alapati VR, McKenzie C, Blair A, Kenny D, MacDonald A, Shaw AM. Mechanisms of U46619- and 5-HT-induced contraction of bovine pulmonary arteries: role of chloride ions. Br J Pharmacol 2007; 151:1224-34. [PMID: 17592513 PMCID: PMC2189823 DOI: 10.1038/sj.bjp.0707338] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND AND PURPOSE Thromboxane A(2) and 5-hydroxytryptamine (5-HT) are implicated in pulmonary hypertension. The involvement of chloride, voltage-operated calcium channels (VOCCs), store-operated calcium channels (SOCCs) and the Rho kinase in the contractile response of bovine pulmonary arteries (BPA) to the thromboxane A(2) mimetic U46619 and 5-HT was investigated. EXPERIMENTAL APPROACH Endothelium-intact ring segments of BPA were mounted in Krebs/Henseleit buffer (37 degrees C) under a tension of 2g and gassed with 95%O(2)/5%CO(2). KEY RESULTS Depletion or removal of extracellular chloride, inhibition of chloride and SOCC, Na:K:2Cl, Cl/HCO(3), Rho kinase inhibited contractions to U46619. Combining Rho kinase inhibition and chloride channel blockade (with NPPB) almost abolished the contractions to U46619. In contrast 5-HT-induced contraction was inhibited by verapamil and mibefradil. Depletion of stored calcium with caffeine almost abolished the response to U46619 but not 5-HT. The contraction by the sarco(endo)plasmic reticulum Ca(2+)-ATPase inhibitor CPA was abolished by SOCC and chloride channel blockade (with NPPB) and by chloride depletion. CONCLUSIONS AND IMPLICATIONS This study suggests that the contractile response of BPA to U46619 involves Rho kinase together with a chloride-sensitive mechanism, which does not involve VOCC but may have a role in calcium release and calcium entry via SOCC. In contrast contraction of the BPA by 5-HT appears to involve verapamil- and mibefradil-sensitive VOCC. This study may indicate that the use of calcium channel blockers in the management of pulmonary hypertension may not always be effective and that Rho kinase and chloride channels may be targets for the development of new therapies.
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Affiliation(s)
- V R Alapati
- Department of Biological and Biomedical Sciences, Glasgow Caledonian University Glasgow, UK
| | - C McKenzie
- Department of Biological and Biomedical Sciences, Glasgow Caledonian University Glasgow, UK
| | - A Blair
- Department of Biological and Biomedical Sciences, Glasgow Caledonian University Glasgow, UK
| | - D Kenny
- Department of Biological and Biomedical Sciences, Glasgow Caledonian University Glasgow, UK
| | - A MacDonald
- Department of Biological and Biomedical Sciences, Glasgow Caledonian University Glasgow, UK
| | - A M Shaw
- Department of Biological and Biomedical Sciences, Glasgow Caledonian University Glasgow, UK
- Author for correspondence:
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Saleh SN, Angermann JE, Sones WR, Leblanc N, Greenwood IA. Stimulation of Ca2+-gated Cl- currents by the calcium-dependent K+ channel modulators NS1619 [1,3-dihydro-1-[2-hydroxy-5-(trifluoromethyl)phenyl]-5-(trifluoromethyl)-2H-benzimidazol-2-one] and isopimaric acid. J Pharmacol Exp Ther 2007; 321:1075-84. [PMID: 17347326 DOI: 10.1124/jpet.106.118786] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Because chloride (Cl(-)) channel blockers such as niflumic acid enhance large-conductance Ca(2+)-activated potassium channels (BK(Ca)), the aim of this study was to determine whether there is a reciprocal modification of Ca(2+)-activated chloride Cl(-) currents (I(ClCa)) by two selective activators of BK(Ca). Single smooth muscle cells were isolated by enzymatic digestion from murine portal vein and rabbit pulmonary artery. The BK(Ca) activators NS1619 [1,3-dihydro-1-[2-hydroxy-5-(trifluoromethyl-)phenyl]-5-(trifluoromethyl)-2H-benzimidazol-2-one] and isopimaric acid (IpA) augmented macroscopic I(ClCa) elicited by pipette solutions containing [Ca(2+)](i) > 100 nM without any alteration in current kinetics. Enhanced currents recorded in the presence of NS1619 or IpA reversed at the theoretical Cl(-) equilibrium potential, which was shifted by approximately -40 mV upon replacement of the external anion with the more permeable thiocyanate anion. NS1619 increased the sensitivity of calcium-activated chloride channel (Cl(Ca)) to Ca(2+) (approximately 100 nM at +60 mV) and induced a leftward shift in their voltage dependence (approximately 80 mV with 1 micro Ca(2+)). Single-channel experiments revealed that NS1619 increased the number of open channels times the open probability of small-conductance (1.8-3.1 pS) Cl(Ca) without any alteration in their unitary amplitude or number of observable unitary levels of activity. These data, in addition to the established stimulatory effects of niflumic acid on BK(Ca), show that there is similarity in the pharmacology of calcium-activated chloride and potassium channels. Although nonspecific interactions are possible, one alternative hypothesis is that the channel underlying vascular I(ClCa) shares some structural similarity to the BK(Ca) or that the latter K(+) channel physically interacts with Cl(Ca).
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Affiliation(s)
- Sohag N Saleh
- Ion Channels and Cell Signaling Research Centre, Division of Basic Medical Sciences, St. George's, University of London, SW17 0RE London, UK
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Greenwood IA, Leblanc N. Overlapping pharmacology of Ca2+-activated Cl- and K+ channels. Trends Pharmacol Sci 2006; 28:1-5. [PMID: 17150263 DOI: 10.1016/j.tips.2006.11.004] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2006] [Revised: 10/13/2006] [Accepted: 11/22/2006] [Indexed: 11/22/2022]
Abstract
Research into Ca2+-activated Cl- channels is hampered by the inability to decipher their molecular identity and the fact that all extant Cl- channel blockers have effects on other ion channels. Most notably, Cl- channel blockers such as the fenamates (e.g. niflumic acid and flufenamic acid) activate Ca2+-dependent K+ channels, although other pharmacological overlaps have been discovered. In this article, we highlight the complex pharmacology of Ca2+-activated Cl- channels and the caveats associated with using these blockers--a necessary requirement because many researchers use Cl- channel blockers as probes for Cl- channel activity. Moreover, we discuss the argument for a common structural motif between Ca2+-activated Cl- channels and Ca2+-dependent K+ channels, which has led to the possibility that the molecular identity of Cl- channels will be revealed by research in this new direction, in addition to the use of existing candidates such as the CLCA, Bestrophin and tweety genes.
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Affiliation(s)
- Iain A Greenwood
- Ion Channels and Cell Signalling Research Centre, Division of Basic Medical Sciences, St George's, University of London, London SW17 0RE, UK.
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Sutliff RL, Conforti L, Weber CS, Kranias EG, Paul RJ. Regulation of the spontaneous contractile activity of the portal vein by the sarcoplasmic reticulum: evidence from the phospholamban gene-ablated mouse. Vascul Pharmacol 2005; 41:197-204. [PMID: 15653095 DOI: 10.1016/j.vph.2004.11.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2003] [Revised: 10/04/2004] [Accepted: 11/04/2004] [Indexed: 12/30/2022]
Abstract
The rapid contraction/relaxation cycles of phasic smooth muscles necessitates intracellular calcium cycling at a more rapid rate than that of tonic smooth muscles. Recent studies suggest that sarcoplasmic reticulum calcium handling is an important determinant of portal vein phasic contractions. We evaluated the importance and role of phospholamban, a protein which inhibits the sarcoplasmic reticulum (SR) calcium ATPase (SERCA), in regulating the contractility of the phasic mouse portal vein. PLB gene ablation significantly reduced the basal frequency of spontaneous mechanical activity and increased force development of the portal vein. Cyclopiazonic acid (CPA), an inhibitor of SERCA, did not significantly affect the spontaneous activity of the wild-type (WT) portal vein. CPA (1 microM) eliminated the differences in frequency and force between the PLB-KO and WT, localizing the effects to the SR. The PLB-KO portal vein had a lower resting membrane potential than WT controls. There were no significant differences between WT and KO responses to charybdotoxin (250 nM), indicating that calcium-activated potassium channels do not contribute to altered KO portal vein contractility. While contractile sensitivity to acetylcholine was not different between WT and PLB-KO portal veins, force generated in response to a given concentration of acetylcholine was significantly greater in the PLB-KO portal vein, both in the absence and presence of CPA. Our results confirm that SR activity can play a major role in modulating the frequency of the spontaneous mechanical activity of portal veins and removal of PLB inhibition of the SR calcium ATPase has significant effects on the spontaneous activity of the portal vein.
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Affiliation(s)
- Roy L Sutliff
- Department of Molecular and Cellular Physiology, University of Cincinnati, 231 Albert Sabin Way, Cincinnati, OH 45267-0576, USA
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15
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Matchkov VV, Aalkjaer C, Nilsson H. Distribution of cGMP-dependent and cGMP-independent Ca(2+)-activated Cl(-) conductances in smooth muscle cells from different vascular beds and colon. Pflugers Arch 2005; 451:371-9. [PMID: 16075241 DOI: 10.1007/s00424-005-1472-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2005] [Accepted: 05/13/2005] [Indexed: 12/22/2022]
Abstract
In the present patch-clamp study we have, for the first time, shown the tissue distribution of a recently characterized cGMP-dependent Ca(2+)-activated Cl(-) conductance [18] in smooth muscle cells freshly isolated from different regions: aorta, pulmonary artery, tail artery, femoral artery, femoral vein, middle cerebral artery, renal artery, portal vein, superior mesenteric artery, mesenteric small artery and colon. The cGMP-dependent Cl(-) conductance has properties distinct from those of the 'classical' Ca(2+)-activated Cl(-) conductances; their different sensitivities to niflumic acid and zinc were here utilized to distinguish them. They were found to be co-expressed in different patterns in smooth muscle cells of different origins. The cGMP-dependent conductance was greater in myocytes from cerebral artery and femoral vein and was greater in the renal artery, aorta, mesenteric small artery, femoral artery and the superior mesenteric artery. The presence of the cGMP-dependent Ca(2+)-activated Cl(-) current in smooth muscle cells isolated from the colon demonstrates that this conductance is not limited to the vasculature. The 'classical' Ca(2+)-activated Cl(-) conductance was strongly expressed in smooth muscle cells from the portal vein and the tail artery, and noticeably higher in the pulmonary artery.
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Affiliation(s)
- Vladimir V Matchkov
- The Water and Salt Research Center, Institute of Physiology and Biophysics, Department of Physiology, University of Aarhus, Building 160, Universitetsparken, 8000 Aarhus, Denmark.
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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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Piper AS, Greenwood IA. Anomalous effect of anthracene-9-carboxylic acid on calcium-activated chloride currents in rabbit pulmonary artery smooth muscle cells. Br J Pharmacol 2003; 138:31-8. [PMID: 12522070 PMCID: PMC1573627 DOI: 10.1038/sj.bjp.0705000] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
1 Ca(2+)-activated Cl(-) currents (I(Cl(Ca))) evoked by K(+)-free pipette solutions containing 500 nM Ca(2+) were recorded in rabbit pulmonary artery smooth muscle cells. A voltage step protocol in which the cells were stepped to +70 mV and then to -80 mV produced outward and inward Cl(-) currents respectively that exhibited distinctive voltage- and time-dependent kinetics that remained consistent for the recording period. 2 Application of the Cl(-) channel inhibitor anthracene-9-carboxylic acid (A-9-C, 500 micro M), produced a small inhibition of the maximum outward Cl(-) current at +70 mV (21+/-10%) but augmented the amplitude of the instantaneous inward relaxation at -80 mV by 321+/-34% (n=12). 3 The current recorded in the absence and presence of A-9-C reversed at the theoretical Cl(-) equilibrium potential and the reversal potential was shifted by about -40 mV upon replacement of external chloride ion by the more permeant anion thiocyanate. Currents in the absence and presence of A-9-C were similarly affected by 100 micro M niflumic acid. 4 Augmentation of the inward current at -80 mV by A-9-C required prior depolarization, i.e. A-9-C did not simply activate a Cl(-) current at negative membrane potentials. Moreover the degree of augmentation was independent of the internal Ca(2+) for concentrations between 100 nM and 1 micro M Ca(2+). 5 The data from the present study confirm previous observations that the inhibitory effect of Cl(-) channel blockers is modified when [Ca(2+)](i) is maintained at higher than normal resting concentrations.
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Affiliation(s)
- Angela S Piper
- Department of Pharmacology & Clinical Pharmacology, St George's Hospital Medical School, London, SW17 0RE
| | - Iain A Greenwood
- Department of Pharmacology & Clinical Pharmacology, St George's Hospital Medical School, London, SW17 0RE
- Author for correspondence:
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Rohra DK, Saito SY, Ohizumi Y. Functional role of Cl- channels in acidic pH-induced contraction of the aorta of spontaneously hypertensive and Wistar Kyoto rats. Eur J Pharmacol 2002; 453:279-86. [PMID: 12398916 DOI: 10.1016/s0014-2999(02)02432-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
pH regulates various cellular functions. Previously, we have described that acidic pH produces depolarization and contraction in isolated aorta from spontaneously hypertensive (SHR) and Wistar Kyoto (WKY) rats [Br. J. Pharmacol. 118 (1996) 485]. The aim of the present study was to investigate the involvement of Cl- channels in acidic pH-induced contraction. Changing the pH of the bathing solution from 7.4 to 6.5 induced a contraction in both SHR and WKY aorta, which was 127.50+/-13.32% and 79.27+/-0.94% of the 64.8 mM KCl-induced contraction, respectively. The acidic pH-induced contraction was partially inhibited by the voltage-dependent Ca2+ channel (VDCC) blockers, verapamil (1 microM) and nifedipine (0.1 microM). The Cl- channel inhibitors, diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS) (0.5 mM), 9-anthracene chloride (0.5 mM), indanyloxyacetic acid (30 microM) and niflumic acid (3 microM) also inhibited the acidic pH-induced contraction and the degree of attenuation was comparable to that of VDCC blockers. DIDS, 9-anthracene chloride and niflumic acid at concentrations used to inhibit the acidic pH-induced contraction also inhibited the 10 microM phenylephrine-induced contraction partially, without affecting the 64.8 mM KCl-induced contraction, whereas both the contractions were inhibited by indanyloxyacetic acid with equal efficacy. Indanyloxyacetic acid but not DIDS, 9-anthracene chloride or niflumic acid inhibited the 24.8 mM KCl-induced contraction. Simultaneous measurement of cytosolic Ca2+ and tension showed that niflumic acid reversed the increase in intracellular Ca2+ level and inhibited the contraction caused by acidic pH. Similarly, acidic pH depolarized the cultured vascular smooth muscle cells from SHR and the depolarization was completely reversible after the administration of niflumic acid. All these results suggest that the activation of Cl- channels is an important mechanism underlying the depolarization and contraction induced by acidic pH in SHR and WKY aortas.
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Affiliation(s)
- Dileep Kumar Rohra
- Department of Pharmaceutical Molecular Biology, Graduate School of Pharmaceutical Sciences, Tohoku University, Aoba, Aramaki, Aoba-ku, 980-8578, Sendai, Japan
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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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20
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Piper AS, Greenwood IA, Large WA. Dual effect of blocking agents on Ca2+-activated Cl(-) currents in rabbit pulmonary artery smooth muscle cells. J Physiol 2002; 539:119-31. [PMID: 11850506 PMCID: PMC2290117 DOI: 10.1113/jphysiol.2001.013270] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The effects of the Cl- channel antagonists, niflumic acid (NFA), dichloro-diphenylamine 2-carboxylic acid (DCDPC) and diisothiocyanato-stilbene-2,2'-disulphonic acid (DIDS) on Ca2+-activated Cl- current (I(Cl(Ca))) evoked by adding fixed intracellular calcium concentrations ([Ca2+]i) to the pipette solution were studied in rabbit pulmonary artery myocytes. With 250 and 500 nM [Ca2+]i bath application of NFA (100 microM) increased inward current at negative potentials, but inhibited outward current at positive potentials. On wash out of NFA, I(Cl(Ca)) was greatly enhanced at all potentials. When external Na+ ions were replaced by N-methyl-D-glucamine (NMDG+) NFA still enhanced I(Cl(Ca)) at negative potentials but the increase of I(Cl(Ca)) on wash out was blocked. When the mean reversal potential (E(r)) of I(Cl(Ca)) was shifted to negative potentials by replacing external Cl- with SCN-, NFA increased inward current but blocked outward current suggesting that the effect of NFA is dependent on current flow. Inclusion of NFA in the pipette solution had no effect on I(Cl(Ca)). Voltage jump experiments indicated that I(Cl(Ca)) displayed characteristic outward current relaxations at +70 mV and inward current relaxations at -80 mV that were abolished by NFA. DCDPC (100 microM) produced similar effects to NFA but 1 mM DIDS produced inhibition of I(Cl(Ca)) at both positive and negative potentials and there was no increase in current on wash out of DIDS. These results suggest that NFA and DCDPC, but not DIDS, simultaneously enhance and block I(Cl(Ca)) by binding to an external site, probably close to the mouth of the chloride channel.
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Affiliation(s)
- A S Piper
- Department of Pharmacology and Clinical Pharmacology, Cardiovascular Research Group, St George's Hospital Medical School, Cranmer Terrace, London SW17 0RE, UK.
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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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Gokina NI, Bevan JA. Role of intracellular Ca(2+) release in histamine-induced depolarization in rabbit middle cerebral artery. Am J Physiol Heart Circ Physiol 2000; 278:H2105-14. [PMID: 10843910 DOI: 10.1152/ajpheart.2000.278.6.h2105] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The role of Ca(2+) mobilization from intracellular stores and Ca(2+)-activated Cl(-) channels in caffeine- and histamine-induced depolarization and contraction of the rabbit middle cerebral artery has been studied by recording membrane potential and isometric force. Caffeine induced a transient contraction and a transient followed by sustained depolarization. The transient depolarization was abolished by ryanodine, DIDS, and niflumic acid, suggesting involvement of Ca(2+)-activated Cl(-) channels. Histamine-evoked transient contraction in Ca(2+)-free solution was abolished by ryanodine or by caffeine-induced depletion of Ca(2+) stores. Ryanodine slowed the development of depolarization induced by histamine in Ca(2+)-containing solution but did not affect its magnitude. In arteries treated with 1 mM Co(2+), histamine elicited a transient depolarization and contraction, which was abolished by ryanodine. DIDS and niflumic acid reduced histamine-evoked depolarization and contraction. Histamine caused a sustained depolarization and contraction in low-Cl(-) solution. These results suggest that Ca(2+) mobilization from ryanodine-sensitive stores is involved in histamine-induced initial, but not sustained, depolarization and contraction. Ca(2+)-activated Cl(-) channels contribute mainly to histamine-induced initial depolarization and less importantly to sustained depolarization, which is most likely dependent on activation of nonselective cation channels.
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Affiliation(s)
- N I Gokina
- Department of Pharmacology, College of Medicine, The University of Vermont, Burlington 05405, USA.
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Pollock NS, Kargacin ME, Kargacin GJ. Chloride channel blockers inhibit Ca2+ uptake by the smooth muscle sarcoplasmic reticulum. Biophys J 1998; 75:1759-66. [PMID: 9746517 PMCID: PMC1299847 DOI: 10.1016/s0006-3495(98)77617-9] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Despite the fact that Ca2+ transport into the sarcoplasmic reticulum (SR) of muscle cells is electrogenic, a potential difference is not maintained across the SR membrane. To achieve electroneutrality, compensatory charge movement must occur during Ca2+ uptake. To examine the role of Cl- in this charge movement in smooth muscle cells, Ca2+ transport into the SR of saponin-permeabilized smooth muscle cells was measured in the presence of various Cl- channel blockers or when I-, Br-, or SO42- was substituted for Cl-. Calcium uptake was inhibited in a dose-dependent manner by 5-nitro-2-(3-phenylpropylamino) benzoic acid (NPPB) and by indanyloxyacetic acid 94 (R(+)-IAA-94), but not by niflumic acid or 4,4'-dinitrostilbene-2,2'-disulfonic acid (DNDS). Smooth muscle SR Ca2+ uptake was also partially inhibited by the substitution of SO42- for Cl-, but not when Cl- was replaced by I- or Br-. Neither NPPB nor R(+)-IAA-94 inhibited Ca2+ uptake into cardiac muscle SR vesicles at concentrations that maximally inhibited uptake in smooth muscle cells. These results indicate that Cl- movement is important for charge compensation in smooth muscle cells and that the Cl- channel or channels involved are different in smooth and cardiac muscle cells.
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Affiliation(s)
- N S Pollock
- Department of Physiology and Biophysics, University of Calgary, Calgary, Alberta T2N 4N1, Canada
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