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1.
Abbara C Estournet B Lacomblez L Lelièvre B Ouslimani A Lehmann B Viollet L Barois A Diquet B 《British journal of clinical pharmacology》2011,71(3):403-410
AIMS
The objective of the present study was to assess the pharmacokinetics of riluzole in patients with spinal muscular atrophy (SMA).METHODS
Fourteen patients were enrolled in an open-label, nonrandomized and repeat-dose pharmacokinetic study. All participants were assigned to receive 50 mg riluzole orally for 5 days. Riluzole plasma concentrations were determined from samples obtained at day 5.RESULTS
The pharmacokinetic analysis demonstrated that a dose of 50 mg once a day was sufficient to obtain a daily total exposure [AUC(0,24 h) = 2257 ng ml−1 h] which was comparable with results obtained in adult healthy volunteers or ALS patients in whom a dose of 50 mg twice a day is recommended. The pharmacokinetic simulation demonstrated that the administration of 50 mg twice a day could result in higher concentrations, hence reduced safety margin.CONCLUSION
The dose of 50 mg once a day was chosen for the clinical trial evaluating the efficacy of riluzole in SMA patients. 相似文献2.
Background and purpose:
TRPC5 is a Ca2+-permeable channel with multiple modes of activation. We have explored the effects of genistein, a plant-derived isoflavone, on TRPC5 activity, and the mechanism(s) involved.Experimental approach:
Effects of genistein on TRPC5 channels were investigated in TRPC5-over-expressing human embryonic kidney 293 (HEK) cells and bovine aortic endothelial cells (BAECs) using fluorescent Ca2+ imaging and electrophysiological techniques.Key results:
In TRPC5-over-expressing HEK cells, genistein stimulated TRPC5-mediated Ca2+ influx, concentration dependently (EC50= 93 µM). Genistein and lanthanum activated TRPC5 channels synergistically. Effects of genistein on TRPC5 channels were mimicked by daidzein (100 µM), a genistein analogue inactive as a tyrosine kinase inhibitor, but not by known tyrosine kinase inhibitors herbimycin (2 µM), PP2 (20 µM) and lavendustin A (10 µM). Action of genistein on TRPC5 channels was not affected by an oestrogen receptor inhibitor ICI-182780 (50 µM) or a phospholipase C inhibitor (10 µM), suggesting genistein did not act through oestrogen receptors or phospholipase C. In BAECs, genistein (100 µM) stimulated TRPC5-mediated Ca2+ influx. In patch clamp studies, both genistein (50 µM) and daidzein (50 µM) augmented TRPC5-mediated whole-cell cation current in TRPC5 over-expressing HEK cells. Genistein stimulated TRPC5 channel activity in excised inside-out membrane patch, suggesting that its action was relatively direct and did not require cytosolic factors. U73122Conclusions and implications:
The present study is the first to demonstrate stimulation of a TRP channel by isoflavones. Genistein is a lipophilic compound able to stimulate TRPC5 activity in TRPC5-over-expressing HEK cells and in native vascular endothelial cells. 相似文献3.
Majeed Y Amer MS Agarwal AK McKeown L Porter KE O'Regan DJ Naylor J Fishwick CW Muraki K Beech DJ 《British journal of pharmacology》2011,162(7):1509-1520
BACKGROUND AND PURPOSE
Transient receptor potential canonical 5 (TRPC5) channels are widely expressed, including in the CNS, where they potentiate fear responses. They also contribute to other non-selective cation channels that are stimulated by G-protein-coupled receptor agonists and lipid and redox factors. Steroids are known to modulate fear and anxiety states, and we therefore investigated whether TRPC5 exhibited sensitivity to steroids.EXPERIMENTAL APPROACH
Human TRPC5 channels were conditionally expressed in HEK293 cells and studied using intracellular Ca2+ measurement, whole-cell voltage-clamp and excised patch techniques. For comparison, control experiments were performed with cells lacking TRPC5 channels or expressing another TRP channel, TRPM2. Native TRPC channel activity was recorded from vascular smooth muscle cells.KEY RESULTS
Extracellular application of pregnenolone sulphate, pregnanolone sulphate, pregnanolone, progesterone or dihydrotestosterone inhibited TRPC5 activity within 1–2 min. Dehydroepiandrosterone sulphate or 17β-oestradiol had weak inhibitory effects. Pregnenolone, and allopregnanolone, a progesterone metabolite and stereo-isomer of pregnanolone, all had no effects. Progesterone was the most potent of the steroids, especially against TRPC5 channel activity evoked by sphingosine-1-phosphate. In outside-out patch recordings, bath-applied progesterone and dihydrotestosterone had strong and reversible effects, suggesting relatively direct mechanisms of action. Progesterone inhibited native TRPC5-containing channel activity, evoked by oxidized phospholipid.CONCLUSIONS AND IMPLICATIONS
Our data suggest that TRPC5 channels are susceptible to relatively direct and rapid stereo-selective steroid modulation, leading to channel inhibition. The study adds to growing appreciation of TRP channels as non-genomic steroid sensors. 相似文献4.
BACKGROUND AND PURPOSE
EndothelinA (ETA) receptor-operated canonical transient receptor potential (TRPC) channels mediate Ca2+ influx pathways, which are important in coronary artery function. Biochemical pathways linking ETA receptor stimulation to TRPC channel opening are unknown. We investigated the involvement of phosphatidylinositol 3-kinases (PI3K) in ETA receptor activation of native heteromeric TRPC1/C5/C6 and TRPC3/C7 channels in rabbit coronary artery vascular smooth muscle cells (VSMCs).EXPERIMENTAL APPROACH
A pharmacological profile of PI3K was created by studying the effect of pan-PI3K, pan-Class I PI3K and Class I PI3K isoform-selective inhibitors on ETA receptor-evoked single TRPC1/C5/C6 and TRPC3/C7 channel activities in cell-attached patches from rabbit freshly isolated coronary artery VSMCs. The action of phosphatidylinositol 3-phosphate- [PI(3)P], 4-phosphate- [PI(4)P] and 5-phosphate- [PI(5)P] containing molecules involved in PI3K-mediated reactions were studied in inside-out patches. Expression of PI3K family members in coronary artery tissue lysates were analysed using quantitative PCR.KEY RESULTS
ETA receptor-operated TRPC1/C5/C6 and TRPC3/C7 channel activities were inhibited by wortmannin. However, ZSTK474 and AS252424 reduced ETA receptor-evoked TRPC1/C5/C6 channel activity but potentiated TRPC3/C7 channel activity. All the PI(3)P-, PI(4)P- and PI(5)P-containing molecules tested induced TRPC1/C5/C6 channel activation, whereas only PI(3)P stimulated TRPC3/C7 channels.CONCLUSIONS AND IMPLICATIONS
ETA receptor-operated native TRPC1/C5/C6 and TRPC3/C7 channel activities are likely to be mediated by Class I PI3Kγ and Class II/III PI3K isoforms, respectively. ETA receptor-evoked and constitutively active PI3Kγ-mediated pathways inhibit TRPC3/C7 channel activation. PI3K-mediated pathways are novel regulators of native TRPC channels in VSMCs, and these signalling cascades are potential pharmacological targets for coronary artery disease. 相似文献5.
Background and purpose:
Current strategies to ameliorate cardiac ischaemic and reperfusion damage, including block of the sodium-hydrogen exchanger, are therapeutically ineffective. Here we propose a different approach, block of the persistent sodium current (INaP).Experimental approach:
Left ventricular pressure was measured as an index of functional deficit in isolated, Langendorff perfused, hearts from adult rats, subjected to 30 min global ischaemia and reperfusion with vehicle only (control) or riluzole (1–10 µM) in the perfusate. Cell shortening and intracellular Ca2+ concentrations [Ca2+]i were measured in adult rat isolated myocytes subjected to hypoxia and re-oxygenation. The block of transient and persistent sodium currents by concentrations of riluzole between 0.01 and 100 µM were assessed in rat isolated myocytes using patch clamp techniques.Key results:
In perfused hearts, riluzole produced a concentration-dependent cardioprotective action, with minor protection from 1 µM and produced rapid and almost complete recovery upon reperfusion from 3 and 10 µM. In isolated myocytes, riluzole at 3 and 10 µM greatly attenuated or prevented the hypoxia- and reperfusion-induced rise in [Ca2+]i and the contractile deficit. In patch clamp experiments, riluzole blocked the persistent sodium current with an IC50 of 2.7 µM, whereas the block of the transient sodium current was only apparent at concentrations above 30 µM.Conclusions and implications:
Riluzole preferentially blocked INaP and was protective in cardiac ischaemia and reperfusion. Thus block of the persistent sodium current would be a viable method of ameliorating cardiac ischaemic and reperfusion damage. 相似文献6.
Background and purpose:
Isoform-specific ion channel blockers are useful for target validation in drug discovery and can provide the basis for new therapeutic agents and aid in determination of physiological functions of ion channels. The aim of this study was to generate a specific blocker of human TRPM3 channels as a tool to help investigations of this member of the TRP cationic channel family.Experimental approach:
A polyclonal antibody (TM3E3) was made to a conserved peptide of the third extracellular (E3) loop of TRPM3 and tested for binding and functional effect. Studies of channel activity were made by whole-cell planar patch-clamp and fura-2 intracellular Ca2+ measurement.Key results:
Ionic current mediated by TRPM3 was inhibited partially by TM3E3 over a period of 5–10 min. Ca2+ entry in TRPM3-expressing cells was also partially inhibited by TM3E3 in a peptide-specific manner and independently of the type of agonist used to activate TRPM3. TM3E3 had no effect on TRPC5, TRPV4, TRPM2 or an endogenous ATP response.Conclusions and implications:
The data show the successful development of a specific TRPM3 inhibitor and give further confidence in E3 targeting as an approach to producing isoform-specific ion channel blockers. 相似文献7.
H Schleifer B Doleschal M Lichtenegger R Oppenrieder I Derler I Frischauf TN Glasnov CO Kappe C Romanin K Groschner 《British journal of pharmacology》2012,167(8):1712-1722
Background and purpose
Pyrazole derivatives have recently been suggested as selective blockers of transient receptor potential cation (TRPC) channels but their ability to distinguish between the TRPC and Orai pore complexes is ill-defined. This study was designed to characterize a series of pyrazole derivatives in terms of TRPC/Orai selectivity and to delineate consequences of selective suppression of these pathways for mast cell activation.Experimental approach
Pyrazoles were generated by microwave-assisted synthesis and tested for effects on Ca2+ entry by Fura-2 imaging and membrane currents by patch-clamp recording. Experiments were performed in HEK293 cells overexpressing TRPC3 and in RBL-2H3 mast cells, which express classical store-operated Ca2+ entry mediated by Orai channels. The consequences of inhibitory effects on Ca2+ signalling in RBL-2H3 cells were investigated at the level of both degranulation and nuclear factor of activated T-cells activation.Key Results
Pyr3, a previously suggested selective inhibitor of TRPC3, inhibited Orai1- and TRPC3-mediated Ca2+ entry and currents as well as mast cell activation with similar potency. By contrast, Pyr6 exhibited a 37-fold higher potency to inhibit Orai1-mediated Ca2+ entry as compared with TRPC3-mediated Ca2+ entry and potently suppressed mast cell activation. The novel pyrazole Pyr10 displayed substantial selectivity for TRPC3-mediated responses (18-fold) and the selective block of TRPC3 channels by Pyr10 barely affected mast cell activation.Conclusions and Implications
The pyrazole derivatives Pyr6 and Pyr10 are able to distinguish between TRPC and Orai-mediated Ca2+ entry and may serve as useful tools for the analysis of cellular functions of the underlying Ca2+ channels. 相似文献8.
Kjestine Schmidt Galyna Dubrovska Gorm Nielsen Gabor Fesüs Torben R Uhrenholt Pernille B Hansen Thomas Gudermann Alexander Dietrich Maik Gollasch Cor de Wit Ralf K?hler 《British journal of pharmacology》2010,161(8):1722-1733
BACKGROUND AND PURPOSE
TRPC1 channels are expressed in the vasculature and are putative candidates for intracellular Ca2+ handling. However, little is known about their role in endothelium-dependent vasodilatations including endothelium-derived hyperpolarizing factor (EDHF) vasodilatations, which require activation of Ca2+-activated K+ channels (KCa). To provide molecular information on the role of TRPC1 for KCa function and the EDHF signalling complex, we examined endothelium-dependent and independent vasodilatations, KCa currents and smooth muscle contractility in TRPC1-deficient mice (TRPC1-/-).EXPERIMENTAL APPROACH
Vascular responses were studied using pressure/wire myography and intravital microscopy. We performed electrophysiological measurements, and confocal Ca2+ imaging for studying KCa channel functions and Ca2+ sparks.KEY RESULTS
TRPC1 deficiency in carotid arteries produced a twofold augmentation of TRAM-34- and UCL1684-sensitive EDHF-type vasodilatations and of endothelial hyperpolarization to acetylcholine. NO-mediated vasodilatations were unchanged. TRPC1-/- exhibited enhanced EDHF-type vasodilatations in resistance-sized arterioles in vivo associated with reduced spontaneous tone. Endothelial IKCa/SKCa-type KCa currents, smooth muscle cell Ca2+ sparks and associated BKCa-mediated spontaneous transient outward currents were unchanged in TRPC1-/-. Smooth muscle contractility induced by receptor-operated Ca2+ influx or Ca2+ release and endothelium-independent vasodilatations were unaltered in TRPC1-/-. TRPC1-/- exhibited lower systolic blood pressure as determined by tail-cuff blood pressure measurements.CONCLUSIONS AND IMPLICATIONS
Our data demonstrate that TRPC1 acts as a negative regulator of endothelial KCa channel-dependent EDHF-type vasodilatations and thereby contributes to blood pressure regulation. Thus, we propose a specific role of TRPC1 in the EDHF–KCa signalling complex and suggest that pharmacological inhibition of TRPC1, by enhancing EDHF vasodilatations, may be a novel strategy for lowering blood pressure. 相似文献9.
Akiko Kojima Hirotoshi Kitagawa Mariko Omatsu-Kanbe Hiroshi Matsuura Shuichi Nosaka 《British journal of pharmacology》2010,161(8):1734-1750
BACKGROUND AND PURPOSE
The Ca2+ paradox is an important phenomenon associated with Ca2+ overload-mediated cellular injury in myocardium. The present study was undertaken to elucidate molecular and cellular mechanisms for the development of the Ca2+ paradox.EXPERIMENTAL APPROACH
Fluorescence imaging was performed on fluo-3 loaded quiescent mouse ventricular myocytes using confocal laser scanning microscope.KEY RESULTS
The Ca2+ paradox was readily evoked by restoration of the extracellular Ca2+ following 10–20 min of nominally Ca2+-free superfusion. The Ca2+ paradox was significantly reduced by blockers of transient receptor potential canonical (TRPC) channels (2-aminoethoxydiphenyl borate, Gd3+, La3+) and anti-TRPC1 antibody. The sarcoplasmic reticulum (SR) Ca2+ content, assessed by caffeine application, gradually declined during Ca2+-free superfusion, which was further accelerated by metabolic inhibition. Block of SR Ca2+ leak by tetracaine prevented Ca2+ paradox. The Na+/Ca2+ exchange (NCX) blocker KB-R7943 significantly inhibited Ca2+ paradox when applied throughout superfusion period, but had little effect when added for a period of 3 min before and during Ca2+ restoration. The SR Ca2+ content was better preserved during Ca2+ depletion by KB-R7943. Immunocytochemistry confirmed the expression of TRPC1, in addition to TRPC3 and TRPC4, in mouse ventricular myocytes.CONCLUSIONS AND IMPLICATIONS
These results provide evidence that (i) the Ca2+ paradox is primarily mediated by Ca2+ entry through TRPC (probably TRPC1) channels that are presumably activated by SR Ca2+ depletion; and (ii) reverse mode NCX contributes little to the Ca2+ paradox, whereas inhibition of NCX during Ca2+ depletion improves SR Ca2+ loading, and is associated with reduced incidence of Ca2+ paradox in mouse ventricular myocytes. 相似文献10.
JG Doria FR Silva JM Souza LB Vieira TG Carvalho HJ Reis GS Pereira T Dobransky FM Ribeiro 《British journal of pharmacology》2013,169(4):909-921
Background and Purpose
Huntington''s disease (HD) is an autosomal dominant neurodegenerative disorder caused by a polyglutamine expansion in the huntingtin protein. We have previously demonstrated that the cell signalling of the metabotropic glutamate receptor 5 (mGluR5) is altered in a mouse model of HD. Although mGluR5-dependent protective pathways are more activated in HD neurons, intracellular Ca2+ release is also more pronounced, which could contribute to excitotoxicity. In the present study, we aim to investigate whether mGluR5 positive allosteric modulators (PAMs) could activate protective pathways without triggering high levels of Ca2+ release and be neuroprotective in HD.Experimental Approach
We performed a neuronal cell death assay to determine which drugs are neuroprotective, Western blot and Ca2+ release experiments to investigate the molecular mechanisms involved in this neuroprotection, and object recognition task to determine whether the tested drugs could ameliorate HD memory deficit.Key Results
We find that mGluR5 PAMs can protect striatal neurons from the excitotoxic neuronal cell death promoted by elevated concentrations of glutamate and NMDA. mGluR5 PAMs are capable of activating Akt without triggering increased intracellular Ca2+ concentration ([Ca2+]i); and Akt blockage leads to loss of PAM-mediated neuroprotection. Importantly, PAMs'' potential as drugs that may be used to treat neurodegenerative diseases is highlighted by the neuroprotection exerted by mGluR5 PAMs on striatal neurons from a mouse model of HD, BACHD. Moreover, mGluR5 PAMs can activate neuroprotective pathways more robustly in BACHD mice and ameliorate HD memory deficit.Conclusions and Implications
mGluR5 PAMs are potential drugs that may be used to treat neurodegenerative diseases, especially HD. 相似文献11.
BACKGROUND AND PURPOSE
SKF 96365 is well known for its suppressing effect on human glioblastoma growth by inhibiting pre-activated transient receptor potential canonical (TRPC) channels and Ca2+ influx. The effect of SKF 96363 on glioblastoma cells, however, may be multifaceted and this possibility has been largely ignored.EXPERIMENTAL APPROACH
The effects of SKF 96365 on cell cycle and cell viability of cultured human glioblastoma cells were characterized. Western blot, Ca2+ imaging and patch clamp recordings were used to delineate cell death mechanisms. siRNA gene knockdown provided additional evidence.KEY RESULTS
SKF 96365 repressed glioblastoma cell growth via increasing intracellular Ca2+ ([Ca2+]i) irrespective of whether TRPC channels were blocked or not. The effect of SKF 96365 primarily resulted from enhanced reverse operation of the Na+/Ca2+ exchanger (NCX) with an EC50 of 9.79 μM. SKF 96365 arrested the glioblastoma cells in the S and G2 phases and activated p38-MAPK and JNK, which were all prevented by the Ca2+ chelator BAPTA-AM or EGTA. The expression of NCX in glioblastoma cells was significantly higher than in normal human astrocytes. Knockdown of the NCX1 isoforms diminished the effect of SKF 96365 on glioblastoma cells.CONCLUSIONS AND IMPLICATIONS
At the same concentration, SKF 96365 blocks TRPC channels and enhances the reverse mode of the NCX causing [Ca2+]i accumulation and cytotoxicity. This finding suggests an alternative pharmacological mechanism of SKF 96365. It also indicates that modulation of the NCX is an effective method to disrupt Ca2+ homeostasis and suppress human glioblastoma cells. 相似文献12.
Objective:
Streptozotocin (STZ) and sodium nitrite (NaNO2) treatment have been positively correlated with higher incidence of memory loss and experimental dementia. The present study was designed to investigate the potential of the Riluzole, an inhibitor of glutamatergic neurotransmission and activator of TWIK-Related K+ channels with incidences of memory deficits associated with dementia in mice.Materials and Methods:
Dementia was induced in Swiss albino mice by intracerebroventricular STZ (ICV) and by subcutaneous NaNO2 in separate groups of animals. Morris water maze was employed to assess learning and memory of the animals. Biochemical analysis of brain homogenate was performed so as to assess brain acetyl cholinesterase (AChE) activity. Brain thiobarbituric acid reactive species (TBARS) levels and reduced glutathione (GSH) levels were measured to assess total oxidative stress.Results:
Treatment of ICV STZ and NaNO2 produced a significant decrease in water maze performance of mice hence reflecting loss of learning and memory. Furthermore, higher levels of brain AChE activity and oxidative stress were observed in these animals. Administration of riluzole (5 and 10 mg/kg intraperitoneally) successfully attenuated memory deficits as well as ICV STZ- and NaNO2 -induced changes in the levels of brain AChE, TBARS, and GSH.Conclusion:
The memory restorative effects of riluzole in dementia may involve its multiple functions including anti-oxidative and anticholinesterase properties.KEY WORDS: Riluzole, streptozotocin, dementia, TREK, morris water-maze 相似文献13.
Chubanov V Mederos y Schnitzler M Meißner M Schäfer S Abstiens K Hofmann T Gudermann T 《British journal of pharmacology》2012,166(4):1357-1376
BACKGROUND AND PURPOSE
Transient receptor potential cation channel subfamily M member 7 (TRPM7) is a bifunctional protein comprising a TRP ion channel segment linked to an α-type protein kinase domain. TRPM7 is essential for proliferation and cell growth. Up-regulation of TRPM7 function is involved in anoxic neuronal death, cardiac fibrosis and tumour cell proliferation. The goal of this work was to identify non-toxic inhibitors of the TRPM7 channel and to assess the effect of blocking endogenous TRPM7 currents on the phenotype of living cells.EXPERIMENTAL APPROACH
We developed an aequorin bioluminescence-based assay of TRPM7 channel activity and performed a hypothesis-driven screen for inhibitors of the channel. The candidates identified were further assessed electrophysiologically and in cell biological experiments.KEY RESULTS
TRPM7 currents were inhibited by modulators of small conductance Ca2+-activated K+ channels (KCa2.1–2.3; SK) channels, including the antimalarial plant alkaloid quinine, CyPPA, dequalinium, NS8593, SKA31 and UCL 1684. The most potent compound NS8593 (IC50 1.6 µM) specifically targeted TRPM7 as compared with other TRP channels, interfered with Mg2+-dependent regulation of TRPM7 channel and inhibited the motility of cultured cells. NS8593 exhibited full and reversible block of native TRPM7-like currents in HEK 293 cells, freshly isolated smooth muscle cells, primary podocytes and ventricular myocytes.CONCLUSIONS AND IMPLICATIONS
This study reveals a tight overlap in the pharmacological profiles of TRPM7 and KCa2.1–2.3 channels. NS8593 acts as a negative gating modulator of TRPM7 and is well-suited to study functional features and cellular roles of endogenous TRPM7. 相似文献14.
T Maier M Follmann G Hessler H-W Kleemann S Hachtel B Fuchs N Weissmann W Linz T Schmidt M L?hn K Schroeter L Wang H Rütten C Strübing 《British journal of pharmacology》2015,172(14):3650-3660
Background and Purpose
The cation channel transient receptor potential canonical (TRPC) 6 has been associated with several pathologies including focal segmental glomerulosclerosis, pulmonary hypertension and ischaemia reperfusion-induced lung oedema. We set out to discover novel inhibitors of TRPC6 channels and investigate the therapeutic potential of these agents.Experimental Approach
A library of potential TRPC channel inhibitors was designed and synthesized. Activity of the compounds was assessed by measuring intracellular Ca2+ levels. The lead compound SAR7334 was further characterized by whole-cell patch-clamp techniques. The effects of SAR7334 on acute hypoxic pulmonary vasoconstriction (HPV) and systemic BP were investigated.Key Results
SAR7334 inhibited TRPC6, TRPC3 and TRPC7-mediated Ca2+ influx into cells with IC50s of 9.5, 282 and 226 nM, whereas TRPC4 and TRPC5-mediated Ca2+ entry was not affected. Patch-clamp experiments confirmed that the compound blocked TRPC6 currents with an IC50 of 7.9 nM. Furthermore, SAR7334 suppressed TRPC6-dependent acute HPV in isolated perfused lungs from mice. Pharmacokinetic studies of SAR7334 demonstrated that the compound was suitable for chronic oral administration. In an initial short-term study, SAR7334 did not change mean arterial pressure in spontaneously hypertensive rats (SHR).Conclusions and Implications
Our results confirm the role of TRPC6 channels in hypoxic pulmonary vasoregulation and indicate that these channels are unlikely to play a major role in BP regulation in SHR. SAR7334 is a novel, highly potent and bioavailable inhibitor of TRPC6 channels that opens new opportunities for the investigation of TRPC channel function in vivo.Tables of LinksTARGETS | |
---|---|
Ion channelsa2014 | TRPC6 |
TRPC1 | TRPC7 |
TRPC3 | Enzymesb2014 |
TRPC4 | PLC |
TRPC5 |
LIGANDS | |
---|---|
Econazole | |
OAG, 1-oleoyl-2-acetyl-sn-glycerol | |
SKF96365 |
15.
R Macianskiene A Gwanyanya KR Sipido J Vereecke K Mubagwa 《British journal of pharmacology》2010,161(2):416-429
BACKGROUND AND PURPOSE
Interest in non-selective cation channels has increased recently following the discovery of transient receptor potential (TRP) proteins, which constitute many of these channels.EXPERIMENTAL APPROACH
We used the whole-cell patch-clamp technique on isolated ventricular myocytes to investigate the effect of flufenamic acid (FFA) and related drugs on membrane ion currents.KEY RESULTS
With voltage-dependent and other ion channels inhibited, cells that were exposed to FFA, N-(p-amylcinnamoyl)anthranilic acid (ACA), ONO-RS-082 or niflumic acid (NFA) responded with an increase in currents. The induced current reversed at +38 mV, was unaffected by lowering extracellular Cl- concentration or by the removal of extracellular Ca2+ and Mg2+, and its inward but not outward component was suppressed in Na+-free extracellular conditions. The current was suppressed by Gd3+ but was resistant to 2-aminoethoxydiphenyl borate (2-APB) and to amiloride. It could not be induced by the structurally related non-fenamate anti-inflammatory drug diclofenac, nor by the phospholipase-A2 inhibitors bromoenol lactone and bromophenacyl bromide. Muscarinic or α-adrenoceptor activation or application of diacylglycerol failed to induce or modulate the current.CONCLUSIONS AND IMPLICATIONS
Flufenamic acid and related drugs activate a novel channel conductance, where Na+ is likely to be the major charge carrier. The identity of the channel remains unclear, but it is unlikely to be due to Ca2+-activated (e.g. TRPM4/5), Mg2+-sensitive (e.g. TRPM7) or divalent cation-selective TRPs. 相似文献16.
Apigenin, a plant-derived flavone, activates transient receptor potential vanilloid 4 cation channel
Ma X He D Ru X Chen Y Cai Y Bruce IC Xia Q Yao X Jin J 《British journal of pharmacology》2012,166(1):349-358
BACKGROUND AND PURPOSE
Transient receptor potential vanilloid 4 (TRPV4) is a Ca2+-permeable channel with multiple modes of activation. Apigenin is a plant-derived flavone, which has potential preventive effects on the development of cardiovascular disease. We set out to explore the effects of apigenin on TRPV4 channel activity and its role in vasodilatation.EXPERIMENTAL APPROACH
The effects of apigenin (0.01–30 µM) on TPRV4 channels were investigated in HEK293 cells over-expressing TRPV4, rat primary cultured mesenteric artery endothelial cells (MAECs) and isolated small mesenteric arterial segments using whole-cell patch clamp, fluorescent Ca2+ imaging, intracellular recording and pressure myography.KEY RESULTS
Whole-cell patch clamp and fluorescent Ca2+ imaging in HEK cells over-expressing TRPV4 showed that apigenin concentration-dependently stimulated the TRPV4-mediated cation current and Ca2+ influx. In MAECs, apigenin stimulated Ca2+ influx in a concentration-dependent manner. These increases in cation current and Ca2+ influx were markedly inhibited by TRPV4-specific blockers and siRNAs. Furthermore, pressure myography and intracellular recording in small third-order mesenteric arteries showed that apigenin dose-dependently evoked smooth muscle cell membrane hyperpolarization and subsequent vascular dilatation, which were significantly inhibited by TRPV4-specific blockers. TRPV4 blocker or charybdotoxin (200 nM) plus apamin (100 nM) diminished the apigenin-induced dilatation.CONCLUSION AND IMPLICATIONS
This is the first study to demonstrate the selective stimulation of TRPV4 by apigenin. Apigenin was found to activate TRPV4 channels in a dose-dependent manner in HEK cells over-expressing TRPV4 and in native endothelial cells. In rat small mesenteric arteries, apigenin acts on TRPV4 in endothelial cells to induce EDHF-mediated vascular dilatation. 相似文献17.
Klose C Straub I Riehle M Ranta F Krautwurst D Ullrich S Meyerhof W Harteneck C 《British journal of pharmacology》2011,162(8):1757-1769
BACKGROUND AND PURPOSE
Fenamates are N-phenyl-substituted anthranilic acid derivatives clinically used as non-steroid anti-inflammatory drugs in pain treatment. Reports describing fenamates as tools to interfere with cellular volume regulation attracted our attention based on our interest in the role of the volume-modulated transient receptor potential (TRP) channels TRPM3 and TRPV4.EXPERIMENTAL APPROACH
Firstly, we measured the blocking potencies and selectivities of fenamates on TRPM3 and TRPV4 as well as TRPC6 and TRPM2 by Ca2+ imaging in the heterologous HEK293 cell system. Secondly, we further investigated the effects of mefenamic acid on cytosolic Ca2+ and on the membrane voltage in single HEK293 cells that exogenously express TRPM3. Thirdly, in insulin-secreting INS-1E cells, which endogenously express TRPM3, we validated the effect of mefenamic acid on cytosolic Ca2+ and insulin secretion.KEY RESULTS
We identified and characterized mefenamic acid as a selective and potent TRPM3 blocker, whereas other fenamate structures non-selectively blocked TRPM3, TRPV4, TRPC6 and TRPM2.CONCLUSIONS AND IMPLICATIONS
This study reveals that mefenamic acid selectively inhibits TRPM3-mediated calcium entry. This selectivity was further confirmed using insulin-secreting cells. KATP channel-dependent increases in cytosolic Ca2+ and insulin secretion were not blocked by mefenamic acid, but the selective stimulation of TRPM3-dependent Ca2+ entry and insulin secretion induced by pregnenolone sulphate were inhibited. However, the physiological regulator of TRPM3 in insulin-secreting cells remains to be elucidated, as well as the conditions under which the inhibition of TRPM3 can impair pancreatic β-cell function. Our results strongly suggest mefenamic acid is the most selective fenamate to interfere with TRPM3 function. 相似文献18.
G Gonz��lez D Zald��var ED Carrillo A Hern��ndez MC Garc��a JA S��nchez 《British journal of pharmacology》2010,161(5):1172-1185
BACKGROUND AND PURPOSE
Pharmacological preconditioning (PPC) with mitochondrial ATP-sensitive K+ (mitoKATP) channel openers such as diazoxide, leads to cardioprotection against ischaemia. However, effects on Ca2+ homeostasis during PPC, particularly changes in Ca2+ channel activity, are poorly understood. We investigated the effects of PPC on cardiac L-type Ca2+ channels.EXPERIMENTAL APPROACH
PPC was induced in isolated hearts and enzymatically dissociated cardiomyocytes from adult rats by preincubation with diazoxide. We measured reactive oxygen species (ROS) production and Ca2+ signals associated with action potentials using fluorescent probes, and L-type currents using a whole-cell patch-clamp technique. Levels of the α1c subunit of L-type channels in the cellular membrane were measured by Western blot.KEY RESULTS
PPC was accompanied by a 50% reduction in α1c subunit levels, and by a reversible fall in L-type current amplitude and Ca2+ transients. These effects were prevented by the ROS scavenger N-acetyl-L-cysteine (NAC), or by the mitoKATP channel blocker 5-hydroxydecanoate (5-HD). PPC signficantly reduced infarct size, an effect blocked by NAC and 5-HD. Nifedipine also conferred protection against infarction when applied during the reperfusion period. Downregulation of the α1c subunit and Ca2+ channel function were prevented in part by the protease inhibitor leupeptin.CONCLUSIONS AND IMPLICATIONS
PPC downregulated the α1c subunit, possibly through ROS. Downregulation involved increased degradation of the Ca2+ channel, which in turn reduced Ca2+ influx, which may attenuate Ca2+ overload during reperfusion. 相似文献19.
Alexander Bondarenko Markus Waldeck-Weiermair Shamim Naghdi Michael Poteser Roland Malli Wolfgang F Graier 《British journal of pharmacology》2010,161(2):308-320
Background and purpose
The glycerol-based lysophospholipid lysophosphatidylinositol (LPI) is an endogenous agonist of the G-protein-coupled receptor 55 (GPR55) exhibiting cannabinoid receptor-like properties in endothelial cells. To estimate the contribution of GPR55 to the physiological effects of LPI, the GPR55-dependent and -independent electrical responses in this cell type were investigated.Experimental approach
Applying small interference RNA-mediated knock-down and transient overexpression, GPR55-dependent and -independent effects of LPI on cytosolic free Ca2+ concentration, membrane potential and transmembrane ion currents were studied in EA.hy296 cells.Key results
In a GPR55-dependent, GDPβS and -sensitive manner, LPI induced rapid and transient intracellular Ca2+ release that was associated with activation of charybdotoxin–sensitive, large conductance, Ca2+-activated, K+ channels (BKCa) and temporary membrane hyperpolarization. Following these initial electrical reactions, LPI elicited GPR55-independent long-lasting Na+ loading and a non-selective inward current causing sustained membrane depolarization that depended on extracellular Ca2+ and Na+ and was partially inhibited by Ni2+ and La3+. This inward current was due to the activation of a voltage-independent non-selective cation current. The Ni2+ and La3+-insensitive depolarization with LPI was prevented by inhibition of the Na/K-ATPase by ouabain. U73122Conclusions and implications
LPI elicited a biphasic response in endothelial cells of which the immediate Ca2+ signalling depends on GPR55 while the subsequent depolarization is due to Na+ loading via non-selective cation channels and an inhibition of the Na/K-ATPase. Thus, LPI is a potent signalling molecule that affects endothelial functions by modulating several cellular electrical responses that are only partially linked to GPR55. 相似文献20.