共查询到20条相似文献,搜索用时 515 毫秒
1.
Thomas EJ Gabriel SE Makhlina M Hardy SP Lethem MI 《American journal of physiology. Cell physiology》2000,279(5):C1578-C1586
The dominant routefor Cl secretion in mouse tracheal epithelium is viaCl channels different from the cystic fibrosis (CF)transmembrane conductance regulator (CFTR), the channel that isdefective in CF. It has been proposed that the use of purinergicagonists to activate these alternative channels in human airways may bebeneficial in CF. In the present study, two conditionally immortalepithelial cell lines were established from the tracheae of micepossessing the tsA58 T antigen gene, one of which [MTE18-(/)] washomozygous for a knockout of CFTR and the other [MTE7b-(+/)]heterozygous for CFTR expression. In Ussing chamber studies, amiloride(104 M) and a cocktail of cAMP-activating agents(forskolin, IBMX, and dibutyryl cAMP) resulted in small changes in theshort-circuit current (Isc) and resistance ofboth cell lines, with larger increases in Iscbeing elicited by ionomycin (106 M). Both cell linesexpressed P2Y2 receptors and responded to thepurinergic agonists ATP, UTP, and 5'-adenylylimidodiphosphate (104 M) with an increase in Isc.This response could be inhibited by DIDS and was abolished in thepresence of Cl-free Ringer solution. Reducing the mucosalCl concentration increased the response to UTP of bothcell lines, with a significantly greater increase in MTE18-(/)cells. Pretreatment of these cells with thapsigargin caused a directincrease in Isc and inhibited the response toUTP. These data suggest that both cell lines expresspurinergic-regulated Cl currents and may prove valuabletools in studying the properties of this pathway. 相似文献
2.
Functional and molecular characterization of an anion exchanger in airway serous epithelial cells 总被引:5,自引:0,他引:5
Loffing J Moyer BD Reynolds D Shmukler BE Alper SL Stanton BA 《American journal of physiology. Cell physiology》2000,279(4):C1016-C1023
Serous cells secreteCl and HCO3 and play an importantrole in airway function. Recent studies suggest that aCl/HCO3 anion exchanger (AE) maycontribute to Cl secretion by airway epithelial cells.However, the molecular identity, the cellular location, and thecontribution of AEs to Cl secretion in serous epithelialcells in tracheal submucosal glands are unknown. The goal of thepresent study was to determine the molecular identity, the cellularlocation, and the role of AEs in the function of serous epithelialcells. To this end, Calu-3 cells, a human airway cell line with aserous-cell phenotype, were studied by RT-PCR, immunoblot, andelectrophysiological analysis to examine the role of AEs inCl secretion. In addition, the subcellular location of AEproteins was examined by immunofluorescence microscopy. Calu-3 cellsexpressed mRNA and protein for AE2 as determined by RT-PCR and Westernblot analysis, respectively. Immunofluorescence microscopy identified AE2 in the basolateral membrane of Calu-3 cells in culture and rattracheal serous cells in situ. InCl/HCO3/Na+-containingmedia, the 8-(4-chlorophenylthio)adenosine 3',5'-cyclic monophosphate(CPT-cAMP)-stimulated short-circuit anion current (Isc) was reduced by basolateral but not byapical application of 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid(50 µM) and 4,4'-dinitrostilbene-2,2'-disulfonic acid [DNDS (500 µM)], inhibitors of AEs. In the absence of Na+ in thebath solutions, to eliminate the contributions of the Na+/HCO3 andNa+/K+/2Cl cotransporters toIsc, CPT-cAMP stimulated a small DNDS-sensitive Isc. Taken together with previous studies, theseobservations suggest that a small component of cAMP-stimulatedIsc across serous cells may be referable toCl secretion and that uptake of Cl acrossthe basolateral membrane may be mediated by AE2. 相似文献
3.
Astrocytes from Na(+)-K(+)-Cl(-) cotransporter-null mice exhibit absence of swelling and decrease in EAA release 总被引:1,自引:0,他引:1
Su G Kintner DB Flagella M Shull GE Sun D 《American journal of physiology. Cell physiology》2002,282(5):C1147-C1160
We reported previously that inhibition ofNa+-K+-Cl cotransporter isoform 1 (NKCC1) by bumetanide abolishes high extracellular K+concentration ([K+]o)-induced swelling andintracellular Cl accumulation in rat cortical astrocytes.In this report, we extended our study by using cortical astrocytes fromNKCC1-deficient (NKCC1/) mice. NKCC1 protein andactivity were absent in NKCC1/ astrocytes.[K+]o of 75 mM increased NKCC1 activityapproximately fourfold in NKCC1+/+ cells (P < 0.05) but had no effect in NKCC1/ astrocytes.Intracellular Cl was increased by 70% inNKCC1+/+ astrocytes under 75 mM[K+]o (P < 0.05) butremained unchanged in NKCC1/ astrocytes. Baselineintracellular Na+ concentration([Na+]i) in NKCC1+/+ astrocyteswas 19.0 ± 0.5 mM, compared with 16.9 ± 0.3 mM[Na+]i in NKCC1/ astrocytes(P < 0.05). Relative cell volume ofNKCC1+/+ astrocytes increased by 13 ± 2% in 75 mM[K+]o, compared with a value of 1.0 ± 0.5% in NKCC1/ astrocytes (P < 0.05).Regulatory volume increase after hypertonic shrinkage was completelyimpaired in NKCC1/ astrocytes.High-[K+]o-induced 14C-labeledD-aspartate release was reduced by ~30% inNKCC1/ astrocytes. Our study suggests that stimulationof NKCC1 is required for high-[K+]o-inducedswelling, which contributes to glutamate release from astrocytes underhigh [K+]o. 相似文献
4.
Tewari KP Malinowska DH Sherry AM Cuppoletti J 《American journal of physiology. Cell physiology》2000,279(1):C40-C50
An HEK-293 cell line stably expressing the humanrecombinant ClC-2 Cl channel was used in patch-clampstudies to study its regulation. The relative permeabilityPx/PCl calculated fromreversal potentials was I > Cl = NO3 = SCNBr. Theabsolute permeability calculated from conductance ratios wasCl = Br = NO3 SCN > I. The channel was activatedby cAMP-dependent protein kinase (PKA), reduced extracellular pH, oleicacid (C:18 cis9), elaidic acid (C:18trans9), arachidonic acid (AA; C:20cis5,8,11,14), and by inhibitors of AA metabolism,5,8,11,14-eicosatetraynoic acid (ETYA; C:20trans5,8,11,14),-methyl-4-(2-methylpropyl)benzeneacetic acid (ibuprofen), and2-phenyl-1,2-benzisoselenazol-3-[2H]-one (PZ51, ebselen). ClC-2Cl channels were activated by a combination of forskolinplus IBMX and were inhibited by the cell-permeant myristoylated PKAinhibitor (mPKI). Channel activation by reduction of bath pH wasincreased by PKA and prevented by mPKI. AA activation of the ClC-2Cl channel was not inhibited by mPKI or staurosporine andwas therefore independent of PKA or protein kinase C activation. 相似文献
5.
CFTR drives Na+-nHCO-3 cotransport in pancreatic duct cells: a basis for defective HCO-3 secretion in CF 总被引:1,自引:0,他引:1
Shumaker Holli; Amlal Hassane; Frizzell Raymond; Ulrich Charles D. II; Soleimani Manoocher 《American journal of physiology. Cell physiology》1999,276(1):C16
Pancreatic dysfunction in patients with cystic fibrosis (CF) isfelt to result primarily from impairment of ductalHCO3 secretion. We provide molecularevidence for the expression of NBC-1, an electrogenicNa+-HCO3cotransporter (NBC) in cultured human pancreatic ductcells exhibiting physiological features prototypical of CF ductfragments (CFPAC-1 cells) or normal duct fragments [CAPAN-1 cellsand CFPAC-1 cells transfected with wild-type CF transmembraneconductance regulator (CFTR)]. We further demonstrate that1)HCO3 uptake across the basolateralmembranes of pancreatic duct cells is mediated via NBC and2) cAMP potentiates NBC activitythrough activation of CFTR-mediatedCl secretion. We proposethat the defect in agonist-stimulated ductal HCO3 secretion in patients with CF ispredominantly due to decreased NBC-drivenHCO3 entry at the basolateralmembrane, secondary to the lack of sufficient electrogenic drivingforce in the absence of functional CFTR. 相似文献
6.
Apical and basolateral CO2-HCO-3 permeability in cultured bovine corneal endothelial cells 总被引:1,自引:0,他引:1
Bonanno Joseph A.; Guan Yi; Jelamskii Sergey; Kang Xiao Jun 《American journal of physiology. Cell physiology》1999,277(3):C545
Corneal endothelial function is dependent onHCO3 transport. However, the relativeHCO3 permeabilities of the apical andbasolateral membranes are unknown. Using changes in intracellular pHsecondary to removingCO2-HCO3 (at constant pH) or removing HCO3alone (at constant CO2) fromapical or basolateral compartments, we determined the relative apicaland basolateral HCO3 permeabilities and their dependencies on Na+ andCl. Removal ofCO2-HCO3from the apical side caused a steady-state alkalinization (+0.08 pHunits), and removal from the basolateral side caused an acidification(0.05 pH units). Removal ofHCO3 at constantCO2 indicated that the basolateralHCO3 fluxes were about three to fourtimes the apical fluxes. Reducing perfusateNa+ concentration to 10 mM had noeffect on apical flux but slowed basolateralHCO3 flux by one-half. In the absence of Cl, there was anapparent increase in apical HCO3 fluxunder constant-pH conditions; however, no net change could be measuredunder constant-CO2 conditions.Basolateral flux was slowed ~30% in the absence ofCl, but the net flux wasunchanged. The steady-state alkalinization after removal ofCO2-HCO3apically suggests that CO2diffusion may contribute to apicalHCO3 flux through the action of amembrane-associated carbonic anhydrase. Indeed, apicalCO2 fluxes were inhibited by theextracellular carbonic anhydrase inhibitor benzolamide and partiallyrestored by exogenous carbonic anhydrase. The presence ofmembrane-bound carbonic anhydrase (CAIV) was confirmed byimmunoblotting. We conclude that theNa+-dependent basolateralHCO3 permeability is consistent withNa+-nHCO3cotransport. Changes inHCO3 flux in the absence ofCl are most likely due toNa+-nHCO3cotransport-induced membrane potential changes that cannot bedissipated. Apical HCO3 permeabilityis relatively low, but may be augmented byCO2 diffusion in conjunction witha CAIV. 相似文献
7.
Xiao GQ Qu Y Sun ZQ Mochly-Rosen D Boutjdir M 《American journal of physiology. Cell physiology》2001,281(5):C1477-C1486
Investigation of the role ofindividual protein kinase C (PKC) isozymes in the regulation ofNa+ channels has been largely limited by the lack ofisozyme-selective modulators. Here we used a novel peptide-specificactivator (V1-7) of PKC and other peptide isozyme-specificinhibitors in addition to the general PKC activator phorbol12-myristate 13-acetate (PMA) to dissect the role of individual PKCs inthe regulation of the human cardiac Na+ channel hH1,heterologously expressed in Xenopus oocytes. Peptides wereinjected individually or in combination into the oocyte. Whole cellNa+ current (INa) was recorded usingtwo-electrode voltage clamp. V1-7 (100 nM) and PMA (100 nM)inhibited INa by 31 ± 5% and 44 ± 8% (at 20 mV), respectively. These effects were not seen with thescrambled peptide for V1-7 (100 nM) or the PMA analog4-phorbol 12,13-didecanoate (100 nM). However, V1-7-and PMA-induced INa inhibition was abolished byV1-2, a peptide-specific antagonist of PKC. Furthermore,PMA-induced INa inhibition was not altered by100 nM peptide-specific inhibitors for -, -, -, or PKC. PMAand V1-7 induced translocation of PKC from soluble toparticulate fraction in Xenopus oocytes. This translocationwas antagonized by V1-2. In native rat ventricular myocytes,PMA and V1-7 also inhibited INa; thisinhibition was antagonized by V1-2. In conclusion, the resultsprovide evidence for selective regulation of cardiac Na+channels by PKC isozyme. 相似文献
8.
Adrenergic stimulation of Na+ transport across alveolar epithelial cells involves activation of apical Cl- channels 总被引:6,自引:0,他引:6
Jiang Xinpo; Ingbar David H.; O'Grady Scott M. 《American journal of physiology. Cell physiology》1998,275(6):C1610
Alveolar epithelial cells were isolated from adultSprague-Dawley rats and grown to confluence on membrane filters. Mostof the basal short-circuit current(Isc; 60%) wasinhibited by amiloride (IC50 0.96 µM) or benzamil (IC50 0.5 µM).Basolateral addition of terbutaline (2 µM) produced a rapid decreasein Isc, followed by a slow recovery back to its initial amplitude. WhenCl was replaced withmethanesulfonic acid, the basalIsc was reduced and the response to terbutaline was inhibited. In permeabilized monolayer experiments, both terbutaline and amiloride produced sustained decreases in current. The current-voltage relationship of the terbutaline-sensitive current had a reversal potential of28 mV. Increasing Cl concentration in thebasolateral solution shifted the reversal potential to more depolarizedvoltages. These results were consistent with the existence of aterbutaline-activated Cl conductance in the apicalmembrane. Terbutaline did not increase the amiloride-sensitiveNa+ conductance. We conclude that -adrenergicstimulation of adult alveolar epithelial cells results in an increasein apical Cl permeability and thatamiloride-sensitive Na+ channels are not directly affectedby this stimulation. 相似文献
9.
Lyall P Armstrong WM Lyall V 《American journal of physiology. Cell physiology》2000,279(5):C1385-C1392
Effects of HCO3 on protein kinase C (PKC)-and protein kinase A (PKA)-induced anion conductances were investigatedin Necturus gallbladder epithelial cells. InHCO3-free media, activation of PKC via12-O-tetradecanoylphorbol 13-acetate (TPA) depolarizedapical membrane potential (Va) and decreased fractional apical voltage ratio (FR). These effects wereblocked by mucosal 5-nitro-2-(3-phenylpropylamino) benzoic acid(NPPB), a Cl channel blocker. In HCO3media, TPA induced significantly greater changes inVa and FR. These effects wereblocked only when NPPB was present in both mucosal and basolateralcompartments. The data suggest that TPA activates NPPB-sensitive apicalCl conductance (gCla) in theabsence of HCO3; in its presence, TPA stimulated bothNPPB-sensitive gCla and basolateralCl conductance (gClb).Activation of PKA via 3-isobutyl-1-methylxanthine (IBMX) also decreased Va and FR; however, thesechanges were not affected by external HCO3. Weconclude that HCO3 modulates the effects of PKC ongClb. In HCO3 medium, TPAand IBMX also induced an initial transient hyperpolarization andincrease in intracellular pH. Because these changes were independent ofmucosal Na+ and Cl, it is suggested that TPAand IBMX induce a transient increase in apical HCO3 conductance. 相似文献
10.
Na+ influx and Na+-K+ pump activation during short-term exposure of cardiac myocytes to aldosterone 总被引:1,自引:0,他引:1
Mihailidou Anastasia S.; Buhagiar Kerrie A.; Rasmussen Helge H. 《American journal of physiology. Cell physiology》1998,274(1):C175
To examine the effect of aldosterone on sarcolemmalNa+ transport, we measuredouabain-sensitive electrogenicNa+-K+pump current(Ip) involtage-clamped ventricular myocytes and intracellularNa+ activity(aiNa) in right ventricularpapillary muscles. Aldosterone (10 nM) induced an increase in bothIp and the rateof rise of aiNa duringNa+-K+pump blockade with the fast-acting cardiac steroid dihydroouabain. Thealdosterone-induced increase inIp and rate ofrise of aiNa was eliminated bybumetanide, suggesting that aldosterone activates Na+ influx through theNa+-K+-2Clcotransporter. To obtain independent support for this, theNa+,K+, andCl concentrations in thesuperfusate and solution of pipettes used to voltage clamp myocyteswere set at levels designed to abolish the inward electrochemicaldriving force for theNa+-K+-2Clcotransporter. This eliminated the aldosterone-induced increase inIp. We concludethat in vitro exposure of cardiac myocytes to aldosterone activates theNa+-K+-2Clcotransporter to enhance Na+influx and stimulate theNa+-K+pump. 相似文献
11.
KGF prevents hyperoxia-induced reduction of active ion transport in alveolar epithelial cells 总被引:1,自引:0,他引:1
Borok Zea; Mihyu Salim; Fernandes Valentino F.J.; Zhang Xiao-Ling; Kim Kwang-Jin; Lubman Richard L. 《American journal of physiology. Cell physiology》1999,276(6):C1352
We evaluated theeffects of acute hyperoxic exposure on alveolar epithelial cell (AEC)active ion transport and on expression ofNa+ pump(Na+-K+-ATPase)and rat epithelial Na+ channelsubunits. Rat AEC were cultivated in minimal defined serum-free medium(MDSF) on polycarbonate filters. Beginning on day5, confluent monolayers were exposedto either 95% air-5% CO2(normoxia) or 95% O2-5%CO2 (hyperoxia) for 48 h.Transepithelial resistance(Rt) andshort-circuit current(Isc) weredetermined before and after exposure.Na+ channel -, -, and-subunit andNa+-K+-ATPase1- and1-subunit mRNA levels werequantified by Northern analysis.Na+ pump1- and1-subunit protein abundance wasquantified by Western blotting. After hyperoxic exposure,Isc across AECmonolayers decreased by ~60% at 48 h relative to monolayersmaintained under normoxic conditions.Na+ channel -subunit mRNAexpression was reduced by hyperoxia, whereas - and -subunit mRNAexpression was unchanged. Na+ pump1-subunit mRNA was unchanged,whereas 1-subunit mRNA was decreased ~80% by hyperoxia in parallel with a reduction in1-subunit protein. Becausekeratinocyte growth factor (KGF) has recently been shown to upregulateAEC active ion transport and expression ofNa+-K+-ATPaseunder normoxic conditions, we assessed the ability of KGF to preventhyperoxia-induced changes in active ion transport by supplementingmedium with KGF (10 ng/ml) from day2. The presence of KGF prevented theeffects of hyperoxia on ion transport (as measured byIsc) relativeto normoxic controls. Levels of1 mRNA and protein wererelatively preserved in monolayers maintained in MDSF and KGF comparedwith those cultivated in MDSF alone. These results indicate that AECnet active ion transport is decreased after 48 h of hyperoxia, likelyas a result of a decrease in the number of functionalNa+ pumps per cell. KGF largelyprevents this decrease in active ion transport, at least in part, bypreserving Na+ pump expression. 相似文献
12.
CFTR induces the expression of DRA along with Cl(-)/HCO(3)(-) exchange activity in tracheal epithelial cells 总被引:3,自引:0,他引:3
Wheat VJ Shumaker H Burnham C Shull GE Yankaskas JR Soleimani M 《American journal of physiology. Cell physiology》2000,279(1):C62-C71
Thickening of airway mucus and lungdysfunction in cystic fibrosis (CF) results, at least in part, fromabnormal secretion of Cl and HCO3across the tracheal epithelium. The mechanism of the defect in HCO3 secretion is ill defined; however, a lack ofapical Cl/HCO3 exchange may exist inCF. To test this hypothesis, we examined the expression ofCl/HCO3 exchangers in trachealepithelial cells exhibiting physiological features prototypical ofcystic fibrosis [CFT-1 cells, lacking a functional cystic fibrosistransmembrane conductance regulator (CFTR)] or normal trachea (CFT-1cells transfected with functional wild-type CFTR, termed CFT-WT). Cellswere grown on coverslips and were loaded with the pH-sensitive dye2',7'-bis(2-carboxyethyl)-5(6)-carboxyfluorescein, andintracellular pH was monitored. Cl/HCO3exchange activity increased by ~300% in cells transfected with functional CFTR, with activities increasing from 0.034 pH/min in CFT-1cells to 0.11 in CFT-WT cells (P < 0.001, n = 8). This activity was significantly inhibited byDIDS. The mRNA expression of the ubiquitous basolateral AE-2Cl/HCO3 exchanger remained unchanged.However, mRNA encoding DRA, recently shown to be aCl/HCO3 exchanger (Melvin JE, Park K,Richardson L, Schultheis PJ, and Shull GE. J Biol Chem 274:22855-22861, 1999.) was abundantly expressed in cells expressingfunctional CFTR but not in cells that lacked CFTR or that expressedmutant CFTR. In conclusion, CFTR induces the mRNA expression of"downregulated in adenoma" (DRA) and, as a result, upregulates theapical Cl/HCO3 exchanger activity intracheal cells. We propose that the tracheal HCO3secretion defect in patients with CF is partly due to thedownregulation of the apical Cl/HCO3exchange activity mediated by DRA. 相似文献
13.
Similarity of A(3)-adenosine and swelling-activated Cl(-) channels in nonpigmented ciliary epithelial cells 总被引:1,自引:0,他引:1
Carré DA Mitchell CH Peterson-Yantorno K Coca-Prados M Civan MM 《American journal of physiology. Cell physiology》2000,279(2):C440-C451
Chloride release from nonpigmented ciliary epithelial (NPE)cells is a final step in forming aqueous humor, and adenosine stimulates Cl transport by these cells. Whole cell patchclamping of cultured human NPE cells indicated that theA3-selective agonist1-deoxy-1-(6-[([3-iodophenyl]methyl)amino]-9H-purin-9-yl)-N-methyl--D-ribofuranuronamide (IB-MECA) stimulated currents (IIB-MECA) by~90% at +80 mV. Partial replacement of external Clwith aspartate reduced outward currents and shifted the reversal potential (Vrev) from 23 ± 2 mV to0.0 ± 0.7 mV. Nitrate substitution had little effect. Perfusionwith the Cl channel blockers5-nitro-2-(3-phenylpropylamino)benzoic acid (NPPB) and niflumic acidinhibited the currents. Partial Cl replacement withaspartate and NO3, and perfusion with NPPB, hadsimilar effects on the swelling-activated whole cell currents(ISwell). Partial cyclamate substitution for external Cl inhibited inward and outward currents of bothIIB-MECA and ISwell. Bothsets of currents also showed outward rectification and inactivation atlarge depolarizing potentials. The results are consistent with theconcept that A3-subtype adenosine agonists and swellingactivate a common population of Cl channels. 相似文献
14.
Maglova Lilia M.; Crowe William E.; Smith Peter R.; Altamirano Anibal A.; Russell John M. 《American journal of physiology. Cell physiology》1998,275(5):C1330
We examined the effects of human cytomegalovirus (HCMV)infection on theNa+-K+-Clcotransporter (NKCC) in a human fibroblast cell line. Using the Cl-sensitive dye MQAE, weshowed that the mock-infected MRC-5 cells express a functional NKCC.1) IntracellularCl concentration([Cl]i)was significantly reduced from 53.4 ± 3.4 mM to 35.1 ± 3.6 mMfollowing bumetanide treatment. 2)Net Cl efflux caused byreplacement of external Clwith gluconate was bumetanide sensitive.3) InCl-depleted mock-infectedcells, the Cl reuptake rate(in HCO3-free media) was reduced inthe absence of external Na+ and bytreatment with bumetanide. After HCMV infection, we found that although[Cl]iincreased progressively [24 h postexposure (PE), 65.2 ± 4.5 mM; 72 h PE, 80.4 ± 5.0 mM], the bumetanide andNa+ sensitivities of[Cl]iand net Cl uptake and losswere reduced by 24 h PE and abolished by 72 h PE. Western blots usingthe NKCC-specific monoclonal antibody T4 showed an approximatelyninefold decrease in the amount of NKCC protein after 72 h ofinfection. Thus HCMV infection resulted in the abolition of NKCCfunction coincident with the severe reduction in the amount of NKCCprotein expressed. 相似文献
15.
Alterations in airway ion transport in NKCC1-deficient mice 总被引:2,自引:0,他引:2
Grubb B. R.; Pace A. J.; Lee E.; Koller B. H.; Boucher R. C. 《American journal of physiology. Cell physiology》2001,281(2):C615
Airways of Na+-K+-2Cl(NKCC1)-deficient mice (/) were studied in Ussing chambers todetermine the role of the basolateral NKCC1 in transepithelial anionsecretion. The basal short-circuit current (Isc)of tracheae and bronchi from adult mice did not differ betweenNKCC1/ and normal mice, whereas NKCC1/ tracheae from neonatalmice exhibited a significantly reduced basalIsc. In normal mouse tracheae, sensitivity tothe NKCC1 inhibitor bumetanide correlated inversely with the age of themouse. In contrast, tracheae from NKCC1/ mice at all ages wereinsensitive to bumetanide. The anion secretory response to forskolindid not differ between normal and NKCC1/ tissues. However, whenlarger anion secretory responses were induced with UTP, airways fromthe NKCC1/ mice exhibited an attenuated response. Ion substitutionand drug treatment protocols suggested that HCO secretion compensated for reduced Cl secretion inNKCC1/ airway epithelia. The absence of spontaneous airway diseaseor pathology in airways from the NKCC1/ mice suggests that theNKCC1 mutant mice are able to compensate adequately for absence of theNKCC1 protein. 相似文献
16.
ANG II controls Na+-K+(NH+4)-2Cl- cotransport via 20-HETE and PKC in medullary thick ascending limb 总被引:1,自引:0,他引:1
Amlal Hassane; LeGoff Christian; Vernimmen Catherine; Soleimani Manoocher; Paillard Michel; Bichara Maurice 《American journal of physiology. Cell physiology》1998,274(4):C1047
Cell pH was monitored in medullary thick ascending limbs todetermine effects of ANG II onNa+-K+(NH+4)-2Clcotransport. ANG II at 1016to 1012 M inhibited30-50% (P < 0.005),but higher ANG II concentrations were stimulatory compared with the1012 M ANG II levelcotransport activity; eventually,106 M ANG II stimulated34% cotransport activity (P < 0.003). Inhibition by 1012M ANG II was abolished by phospholipase C (PLC), diacylglycerol lipase,or cytochrome P-450-dependentmonooxygenase blockade; 1012 M ANG II had no effectadditive to inhibition by 20-hydroxyeicosatetranoic acid (20-HETE).Stimulation by 106 M ANG IIwas abolished by PLC and protein kinase C (PKC) blockade and waspartially suppressed when the rise in cytosolicCa2+ was prevented. All ANG IIeffects were abolished by DUP-753 (losartan) but not by PD-123319. Thus1012 M ANG II inhibitsvia 20-HETE, whereas 5 × 1011 M ANG II stimulatesvia PKCNa+-K+(NH+4)-2Clcotransport; all ANG II effects involveAT1 receptors and PLC activation. 相似文献
17.
Buhagiar Kerrie A.; Hansen Peter S.; Bewick Nerida L.; Rasmussen Helge H. 《American journal of physiology. Cell physiology》2001,281(3):C1059
A reduction in angiotensinII (ANG II) in vivo by treatment of rabbits with theangiotensin-converting enzyme inhibitor, captopril, increasesNa+-K+ pump current (Ip)of cardiac myocytes. This increase is abolished by exposure of myocytesto ANG II in vitro. Because ANG II induces translocation of the-isoform of protein kinase C (PKC), we examined whether thisisozyme regulates the pump. We treated rabbits with captopril, isolatedmyocytes, and measured Ip of myocytes voltageclamped with wide-tipped patch pipettes. Ip ofmyocytes from captopril-treated rabbits was larger thanIp of myocytes from controls. ANG II superfusionof myocytes from captopril-treated rabbits decreasedIp to levels similar to controls. Inclusion ofPKC-specific blocking peptide in pipette solutions used to perfusethe intracellular compartment abolished the effect of ANG II. Inclusionof RACK, a PKC-specific activating peptide, in pipettesolutions had an effect on Ip that was similarto that of ANG II. There was no additive effect of ANG II andRACK. We conclude that PKC regulates the sarcolemmalNa+-K+ pump. 相似文献
18.
Golovina VA Song H James PF Lingrel JB Blaustein MP 《American journal of physiology. Cell physiology》2003,284(2):C475-C486
The role of the Na+ pump2-subunit in Ca2+ signaling was examined inprimary cultured astrocytes from wild-type(2+/+ = WT) mouse fetuses and thosewith a null mutation in one [2+/ = heterozygote (Het)] or both [2/ = knockout (KO)] 2 genes. Na+ pump catalytic() subunit expression was measured by immunoblot; cytosol[Na+] ([Na+]cyt) and[Ca2+] ([Ca2+]cyt) weremeasured with sodium-binding benzofuran isophthalate and fura 2 byusing digital imaging. Astrocytes express Na+ pumpswith both 1- (80% of total ) and2- (20% of total ) subunits. Het astrocytesexpress 50% of normal 2; those from KO express none.Expression of 1 is normal in both Het and KO cells.Resting [Na+]cyt = 6.5 mM in WT, 6.8 mMin Het (P > 0.05 vs. WT), and 8.0 mM in KO cells(P < 0.001); 500 nM ouabain (inhibits only2) equalized [Na+]cyt at 8 mMin all three cell types. Resting[Ca2+]cyt = 132 nM in WT, 162 nM in Het,and 196 nM in KO cells (both P < 0.001 vs. WT).Cyclopiazonic acid (CPA), which inhibits endoplasmic reticulum (ER)Ca2+ pumps and unloads the ER, induces transient (inCa2+-free media) or sustained (in Ca2+-repletemedia) elevation of [Ca2+]cyt. TheseCa2+ responses to 10 µM CPA were augmented in Het as wellas KO cells. When CPA was applied in Ca2+-free media, thereintroduction of Ca2+ induced significantly largertransient rises in [Ca2+]cyt (due toCa2+ entry through store-operated channels) in Het and KOcells than in WT cells. These results correlate with published evidencethat 2 Na+ pumps andNa+/Ca2+ exchangers are confined to plasmamembrane microdomains that overlie the ER. The data suggest thatselective reduction of 2 Na+ pump activitycan elevate local [Na+] and, viaNa+/Ca2+ exchange, [Ca2+] in thetiny volume of cytosol between the plasma membrane and ER. This, inturn, augments adjacent ER Ca2+ stores and therebyamplifies Ca2+ signaling without elevating bulk[Na+]cyt. 相似文献
19.
Ji Hong-Long; Fuller Catherine M.; Benos Dale J. 《American journal of physiology. Cell physiology》1998,275(5):C1182
The hypothesisthat amiloride-sensitive Na+channels (ENaC) are involved in cell volume regulation was tested.Anisosmotic ND-20 media (ranging from 70 to 450 mosM) were used tosuperfuse Xenopus oocytes expressing-rat ENaC (-rENaC). Whole cell currents werereversibly dependent on external osmolarity. Under conditions ofswelling (70 mosM) or shrinkage (450 mosM), current amplitude decreasedand increased, respectively. In contrast, there was no change incurrent amplitude of H2O-injectedoocytes to the above osmotic insults. Currents recorded from-rENaC-injected oocytes were not sensitive to externalCl concentration or to theK+ channel inhibitorBaCl2. They were sensitive toamiloride. The concentration of amiloride necessary to inhibit one-halfof the maximal rENaC current expressed in oocytes(Ki; apparentdissociation constant) decreased in swollen cells and increased inshrunken oocytes. The osmotic pressure-inducedNa+ currents showed propertiessimilar to those of stretch-activated channels, including inhibition byGd3+ andLa3+, and decreased selectivityfor Na+.-rENaC-expressing oocytes maintained a nearly constant cell volume in hypertonic ND-20. The present study is the firstdemonstration that -rENaC heterologously expressed inXenopus oocytes may contribute tooocyte volume regulation following shrinkage. 相似文献
20.
Cell cycle-dependent expression of volume-activated chloride currents in nasopharyngeal carcinoma cells 总被引:25,自引:0,他引:25
Chen L Wang L Zhu L Nie S Zhang J Zhong P Cai B Luo H Jacob TJ 《American journal of physiology. Cell physiology》2002,283(4):C1313-C1323
Patch-clamping and cell imageanalysis techniques were used to study the expression of thevolume-activated Cl current,ICl(vol), and regulatory volume decrease (RVD)capacity in the cell cycle in nasopharyngeal carcinoma cells (CNE-2Z). Hypotonic challenge caused CNE-2Z cells to swell and activated aCl current with a linear conductance, negligibletime-dependent inactivation, and a reversal potential close to theCl equilibrium potential. The sequence of anionpermeability was I > Br > Cl > gluconate. The Cl channelblockers tamoxifen, 5-nitro-2-(3-phenylpropylamino)benzoic acid (NPPB),and ATP inhibited ICl(vol). Synchronous cultures of cells were obtained by the mitotic shake-off technique and by adouble chemical-block (thymidine and hydroxyurea) technique. Theexpression of ICl(vol) was cell cycle dependent,being high in G1 phase, downregulated in S phase, butincreasing again in M phase. Hypotonic solution activated RVD, whichwas cell cycle dependent and inhibited by the Cl channelblockers NPPB, tamoxifen, and ATP. The expression of ICl(vol) was closely correlated with the RVDcapacity in the cell cycle, suggesting a functional relationship.Inhibition of ICl(vol) by NPPB (100 µM)arrested cells in G0/G1. The data also suggest that expression of ICl(vol) and RVD capacity areactively modulated during the cell cycle. The volume-activatedCl current associated with RVD may therefore play animportant role during the cell cycle progress. 相似文献