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1.
The effects of monensin, an activator of Na(+)/H(+) exchanger (NHE), on capacitative Ca(2+) entry (CCE) were investigated using A7r5 cells. Capacitative Ca(2+) entry was induced by elevation of extracellular Ca(2+) concentrations of A7r5 cells in which stored Ca(2+) had been depleted by previous administration of thapsigargin. Capacitative Ca(2+) entry was abolished by pretreatment of the cells with SKF-96365 (1-[beta-(3-[4-methoxyphenyl]propoxy)-4-methoxyphenethyl]-1H-imidazole hydrochloride) but was not affected by pretreatment with verapamil. Monensin significantly increased capacitative Ca(2+) entry. On the other hand, 5-hydroxytryptamine-induced inositol monophosphate accumulation and subsequent intracellular Ca(2+) release from its stores were significantly inhibited by monensin, while thapsigargin-induced Ca(2+) release was not affected by monensin. These results suggest that monensin has diverse actions on capacitative Ca(2+) entry and agonist-induced release of stored Ca(2+) in vascular smooth muscle cells. 相似文献
2.
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3.
Kazinol B, a natural isoprenylated flavan, stimulated the [Ca2+]i elevation in the presence or absence of Ca2+ in the medium. Treatment with chymotrypsin or phorbol 12-myristate 13-acetate to shedding of l-selectin had no effect on subsequent kazinol B-induced Ca2+ response. Upon initial cyclopiazonic acid (CPA) treatment in the absence of external Ca2+, the subsequent [Ca2+]i rise followed by challenge with kazinol B was greatly diminished. The ryanodine receptor blockers, 8-bromo-cyclic ADP-ribose and ruthenium red did not affect kazinol B-evoked Ca2+ release from internal stores. However, the inhibitors of sphingosine kinase, dimethylsphingosine, but not dihydrosphingosine, inhibited kazinol B-induced Ca2+ release. Kazinol B-induced [Ca2+]i rise was not affected by two nitric oxidase inhibitors, N-(3-aminomethyl)benzylacetamidine (1400W) and 7-nitroindazole, cytochalasin B and Na+-deprivation. This response was slightly attenuated by 2-aminoethyldiphenyl borate (2-APB), a d-myo-inositol 1,4,5-trisphosphate (IP3) receptor blocker, and by genistein, a general tyrosine kinase inhibitor. However, the Ca2+ response was greatly diminished by two actin filament reorganizers, calyculin A and jasplakinolide, 2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one (LY 294002), an inhibitor of phosphoinositide 3-kinase, N-(3-aminomethyl)benzylacetamidine (SB 203580), the p38 mitogen-activated protein kinase inhibitor, 1-[6-[17-3-methoxyestra-1,3,5(10)-trien-17-yl]amino]hexyl]-1H-pyrrole-2,5-dione (U-73122), the inhibitor of phospholipase C-coupled processes, and by 0.3 mM La3+ or Ni2+. Kazinol B did not evoke any appreciable Ba2+ and Sr2+ entry into cells. The Ca2+ entry blockers, 1-[-[3-(4-methoxyphenyl)propoxy]-4-methoxyphenethyl]-1H-imidazole (SKF-96365), but not cis-N-(2-phenylcyclopentyl)azacyclotridec-1-en-2-amine (MDL-12,330A), inhibited a kazinol B-induced [Ca2+]i rise. Kazinol B had no effect on the pharmacologically isolated plasma membrane Ca2+-ATPase activity. In a Ca2+-free medium, kazinol B inhibited the subsequent Ca2+ addition, resulting in robust entry in CPA- and formyl peptide-activated cells. Kazinol B produced a concentration-dependent reduction in the mitochondrial membrane potential. These results indicate that kazinol B stimulates Ca2+ release from internal Ca2+ store, probably through the sphingosine 1-phosphate and IP3 signaling, and activates external Ca2+ influx mainly through a non-store-operated Ca2+ entry (non-SOCE) pathway. Inhibition of SOCE by kazinol B is probably attributable to a break in the Ca2+ driven force of mitochondria. 相似文献
4.
Hiromichi Yamamoto Hideo Kanaide Motoomi Nakamura 《Naunyn-Schmiedeberg's archives of pharmacology》1990,341(4):273-278
Summary By measuring the 45Ca2+ movement in saponin-skinned primary cultured rat aortic smooth muscle cells, we examined the specificity of the inhibitory effect of heparin on the IP3-induced Ca2+ release. IP3 (100 mol/l) markedly (98%) decreased the MgATP-dependent 45Ca2+ content in the non-mitochondrial Ca2+ stores in the presence of 1 mol/l free Ca2+. Heparin (1–100 g/ml) dose-dependently inhibited this Ca2+ release by IP3. In Ca2+-free solution, heparin (100 g/ml) inhibited the increases in 45Ca2+ efflux rate evoked by 10 mol/l IP3. De-N-sulfated heparin did not inhibit the IP3-induced Ca2+ release. Hyaluronic acid, heparan sulfate, chondroitin sulfate A, chondroitin sulfate B, chondroitin sulfate C and 2,6-disulfated d-glucosamine had no inhibitory effects on the IP3-induced Ca2+ release. High concentrations (over 1 mg/ml) of heparin inhibited the 45Ca2+ influx and decreased the Ca2+ content in skinned cells. These results suggest that heparin (1–100 g/ml) specifically inhibits the IP3-induced increase in Ca2+ permeability of Ca2+ stores and that three sulfate groups at different locations on the molecule of heparin, two at the d-glucosamine and one at the iduronic acid, may be important for this action, in skinned vascular smooth muscle cells, in culture.
Send offprint requests to H. Kanaide at the above address 相似文献
5.
Chang YF Teng HC Cheng SY Wang CT Chiou SH Kao LS Kao FJ Chiou A Yang DM 《Toxicology and applied pharmacology》2008,227(3):430-439
Heavy metal lead (Pb2+) is a pollutant and causes severe toxicity when present in human tissues especially the nervous system. Recent reviews have suggested that Pb2+ can target Ca2+-related proteins within neurons and that Ca2+ channels might be a candidate for Pb2+ entry. This study's main aim was to identify the functional entry pathway of Pb2+ into living cells. We firstly characterized the endogenous expression of Orai1 and STIM1 mRNA together with the level of thapsigargin (TG) stimulated capacitative Ca2+ entry in PC12 and HeLa cells; this was done by RT-PCR and time-lapse Ca2+ imaging microscopy, respectively. Our data supported Orai1 and STIM1 as contributing to store-operated Ca2+ channel (SOC) basal activity. Secondly, using the indo-1 quenching method with the SOC blocker 2-APB, we observed that Pb2+ was able to enter cells directly through unactivated SOCs without TG pretreatment. Thirdly, we further demonstrated that co-expression of Orai1 and STIM1 differentially enhanced SOC functional activity (4-fold with PC12 and 5-fold with HeLa cells) and Pb2+ entry (5- to 7-fold with PC12 and 2-fold with HeLa cells). Furthermore, after a 1 h of Pb2+ exposure, the depolarization- and histamine-induced Ca2+ responses were significantly decreased in both PC12 and HeLa cells in a dose-dependent manner. This result indicated that the decreased Ca2+ responses were, in part, due to Pb2+ entry. In summary, our results suggest that SOCs are responsible for Pb2+ permeation and that the Orai1-STIM1 protein complex formed by functional SOCs is one of the molecular components involved in Pb2+ entry. 相似文献
6.
Elevated intracellular Ca2+ content is implicated in ethanol-induced hepatocyte apoptosis and necrosis. Extracellular Ca2+ influx has been suggested to play a role in this process. However, the exact Ca2+-permeable channel involved in the plasma membrane is still unclear. This study investigated the role of store-operated calcium entry (SOCE) in ethanol-induced cytosolic free Ca2+ concentrations ([Ca2+]i) increase and hepatotoxicity. Ethanol (25-800 mM) dose-dependently increased [Ca2+]i content and hepatocyte damage in HepG2 cells. 2-aminoethoxydiphenyl borate (2-APB), the proved efficient antagonist of SOCs, dose-dependently suppressed the ethanol (200 nM)-increased [Ca2+]i content and protected against ethanol-induced viability loss and transaminase leakage. Exposure to 200 mM ethanol for 24 h significantly upregulated the mRNA and protein expression of calcium release-activated calcium channel protein 1 (CRACM1, Orai1) and stromal interaction molecule 1 (STIM1), the two main molecular constituents of SOCs, which was sustained for at least 72 h. In addition, small interfering RNA knockdown of STIM1 attenuated the ethanol-increased [Ca2+]i content and hepatotoxicity. Taken together, these data indicate that the Ca2+ channel of SOCE may be involved in the pathogenesis of ethanol-induced intracellular Ca2+ elevation and consequent hepatocyte damage. 相似文献
7.
Bazán-Perkins B Flores-Soto E Barajas-López C Montaño LM 《Naunyn-Schmiedeberg's archives of pharmacology》2003,368(4):277-283
Depletion of intracellular Ca2+ stores induces the opening of an unknown Ca2+ entry pathway to the cell. We measured the intracellular free-Ca2+ concentration ([Ca2+]i) at different sarcoplasmic reticulum (SR) Ca2+ content in fura-2-loaded smooth muscle cells isolated from bovine tracheas. The absence of Ca2+ in the extracellular medium generated a time-dependent decrement in [Ca2+]i which was proportional to the reduction in the SR-Ca2+ content. This SR-Ca2+ level was indirectly determined by measuring the amount of Ca2+ released by caffeine. Ca2+ restoration at different times after Ca2+-free incubation (2, 4, 6 and 10 min) induced an increment of [Ca2+]i. This increase in [Ca2+]i was considered as Ca2+ entry to the cell. The rate of this entry was slow (~0.3 nM/s) when SR-Ca2+ content was higher than 50% (2 and 4 min in Ca2+-free medium), and significantly (p<0.01) accelerated (>1.0 nM/s) when SR-Ca2+ content was lower than 50% (6 and 10 min in Ca2+-free medium). Thapsigargin significantly induced a higher rate of this Ca2+ entry (p<0.01). Variations in Ca2+ influx after SR-Ca2+ depletion were estimated more directly by a Mn2+ quench approach. Ca2+ restoration to the medium 4 min after Ca2+ removal did not modify the Mn2+ influx. However, when Ca2+ was added after 10 min in Ca2+-free medium, an increment of Mn2+ influx was observed, corroborating an increase in Ca2+ entry. The fast Ca2+ influx was Ni2+ sensitive but was not affected by other known capacitative Ca2+ entry blockers such as La3+, Mg2+, SKF 96365 and 2-APB. It was also not affected by the blockage of L-type Ca2+ channels with methoxyverapamil or by the sustained K+-induced depolarisation. The slow Ca2+ influx was only sensitive to SKF 96365. In conclusion, our results indicate that in bovine airway smooth muscle cells Ca2+ influx after SR-Ca2+ depletion has two rates: A) The slow Ca2+ influx, which occurred in cells with more than 50% of their SR-Ca2+ content, is sensitive to SKF 96365 and appears to be a non-capacitative Ca2+ entry; and B) The fast Ca2+ influx, observed in cells with less than 50% of their SR-Ca2+ content, is probably a capacitative Ca2+ entry and was only Ni2+-sensitive. 相似文献
8.
Ken Nakazawa Hiroshi Saito Norio Matsuki 《Naunyn-Schmiedeberg's archives of pharmacology》1992,346(5):515-522
Summary Effects of calcitonin gene-related peptide (CGRP), a putative non-adrenergic non-cholinergic neutrotransmitter on the electrical properties of the cell membrane, were investigated in enzymically dispersed smooth muscle cells from rat vas deferens. Under current clamp conditions, CGRP (up to 10–7 M) did not induce significant changes in membrane potentials or input resistance in the resting state. The configurations of action potentials elicited by depolarizing current pulses were also unaffected, except that a prolongation of the duration of the action potentials by a high dose (10–7 M) of CGRP was observed in some of the cells. Under whole cell voltage clamp conditions, the transient and sustained K+ currents, activated by depolarizing voltage-steps, were apparently decreased in the presence of 10–9 to 10–7 M CGRP. The peptide increased the voltage-gated Ca2+ current in cells loaded with 145 mM Cs+ solution in order to block the K+ currents. The voltage-dependency of the peak Ca2+ current was not changed by CGRP. Ba2+ (10.8 mM) was used as a charge carrier for the Ca2+-channel current to clarify further the effects of CGRP on the properties of the current. CGRP (10–8 M) delayed the inactivation time course of the Ca2+-channel current and slowed the recovery from inactivation. The peptide did not affect the steady-state inactivation measured by changing the holding potential. The Ca2+-channel current in the presence of CGRP was suppressed by nicardipine (10–6 M) to the same extent as the current under control conditions. The results suggest that CGRP modifies the L-type Ca2+ channel in smooth muscle cells.
Correspondence to N. Matsuki at the above address 相似文献
9.
Sriram Govindan Emily JA Taylor Colin W Taylor 《British journal of pharmacology》2010,160(8):1953-1962
Background and purpose:
P2Y receptors evoke Ca2+ signals in vascular smooth muscle cells and regulate contraction and proliferation, but the roles of the different P2Y receptor subtypes are incompletely resolved.Experimental approach:
Quantitative PCR was used to define expression of mRNA encoding P2Y receptor subtypes in freshly isolated and cultured rat aortic smooth muscle cells (ASMC). Fluorescent indicators in combination with selective ligands were used to measure the changes in cytosolic free [Ca2+] in cultured ASMC evoked by each P2Y receptor subtype.Key results:
The mRNA for all rat P2Y receptor subtypes are expressed at various levels in cultured ASMC. Four P2Y receptor subtypes (P2Y1, P2Y2, P2Y4 and P2Y6) evoke Ca2+ signals that require activation of phospholipase C and comprise both release of Ca2+ from stores and Ca2+ entry across the plasma membrane.Conclusions and implications:
Combining analysis of P2Y receptor expression with functional analyses using selective agonists and antagonists, we isolated the Ca2+ signals evoked in ASMC by activation of P2Y1, P2Y2, P2Y4 and P2Y6 receptors. 相似文献10.
Törnquist K Ramström C Rudnäs B Klika KD Dugué B Adams J Zipkin R Pihlaja K Pasternack M 《European journal of pharmacology》2002,453(1):1-11
Sphingolipid derivatives cause diverse effects towards the regulation of intracellular free Ca(2+) concentrations ([Ca(2+)](i)) in a multitude of nonexcitable cells. In the present investigation, the effect of C-8 ceramide-1-(2-cyanoethyl) phosphate (C1CP) on store-operated Ca(2+) (SOC) entry was investigated. C1CP evoked a modest increase in [Ca(2+)](i). The increase was inhibited by the SOC channel antagonist 1-(beta-[3-(4methoxyphenyl)propoxy]-4-methoxyphenethyl)-1H-imidazole (SKF96365) but not by overnight pretreatment of the cells with pertussis toxin. C1CP did not invoke the production of inositol phosphates. When cells were stimulated with both C1CP and thapsigargin, the thapsigargin-invoked increase in [Ca(2+)](i) was enhanced in comparison to control cells. When Ca(2+) was added to cells treated with both C1CP and thapsigargin in a Ca(2+)-free buffer, the increase in [Ca(2+)](i) was enhanced in comparison to control cells. In patch-clamp experiments, C1CP hyperpolarized the membrane potential (E(m)) of the cells and attenuated the thapsigargin-invoked depolarization of the E(m). The effects of C1CP came, in part, as a result of a decreased conductance of the cell membrane towards Cl(-) ions, as C1CP in a Cl(-)-free solution also enhanced Ca(2+) entry. Barium 2-cyanoethylphosphate (Ba2Cy), which also contains the 2-cyanoethyl group, did not modulate thapsigargin-invoked changes in [Ca(2+)](i) nor did it modulate the E(m). In conclusion, C1CP enhances SOC entry, in part, via hyperpolarization of the E(m) and attenuation of the thapsigargin-invoked membrane depolarization, thus increasing the electrochemical gradient for Ca(2+) ions. Hence, C1CP may be a useful reagent for investigating the cellular effects of ceramide derivatives. 相似文献
11.
Wang GJ Wu XC Lin YL Ren J Shum AY Wu YY Chen CF 《European journal of pharmacology》2002,445(3):239-245
The purpose of the present study was to examine the mechanisms underlying the putative hypotensive actions of iso-S-petasin, a sesquiterpene extract of Petasites formosanus through both in vivo and in vitro experiments. Intravenous administration of iso-S-petasin elicited dose-dependent (0.1-1.5 mg/kg) hypotensive and bradycardiac responses in anesthetized rats. Isometric tension recording in isolated thoracic aorta revealed that iso-S-petasin (0.01-100 microM) inhibited KCl- or Bay K 8644 (1,4-dihydro-2,6-dimethyl-5-nitro-4-[2'-(trifluoromethyl)phenyl]-3-pyridinecarboxylic acid methyl ester)-induced vasoconstriction independent of endothelium. Iso-S-Petasin also attenuated Ca(2+)-induced vasoconstriction in a concentration-dependent manner in Ca(2+)-depleted/high K(+)-depolarized ring segments, indicating that iso-S-petasin inhibited Ca(2+) influx into vascular smooth muscle cells. This was confirmed by whole-cell patch-clamp recording in cultured vascular smooth muscle cells where iso-S-petasin (10-100 microM) appeared to directly inhibit the L-type voltage-dependent Ca(2+) channel (VDCC) activity. Intracellular Ca(2+) concentration ([Ca(2+)](i)) measurements using the fluorescent probe fura-2/AM (1-[2-(5-carboxyoxazol-2-yl)-6-aminobenzofuran-5-oxy]-2-(2'-amino-5'-methylphenoxy)-ethane-N,N,N',N'-tetraacetic acid pentaacetoxymethyl ester) showed suppression of the KCl-stimulated increase in [Ca(2+)](i) by iso-S-petasin (10, 100 microM). In conclusion, these results suggest that Ca(2+) antagonism of the L-type VDCC in vascular smooth muscle cells might largely account for the hypotensive action of iso-S-petasin. 相似文献
12.
The present study was designed to evaluate the effects of antidepressants on smooth muscle contractile activity. In rat aortic rings, the antidepressants imipramine, mianserin and sertraline provoked concentration-dependent inhibitions of the mechanical responses evoked by K+ (30 mM) depolarization. These myorelaxant effects were not modified by the presence of glibenclamide or 80 mM K+ in the bathing medium. Moreover, the vasodilator properties of imipramine were not affected by atropine, phentolamine and pyrilamine. Radioisotopic experiments indicated that imipramine failed to enhance 86Rb outflow from prelabelled and perifused aortic rings whilst counteracting the increase in 45Ca outflow provoked by a rise in the extracellular K+ concentration. Simultaneous measurements of contractile activity and fura-2 fluorescence revealed that, in aortic rings, imipramine reduced the mechanical and fluorimetric response to K+ challenge. In A7r5 smooth muscle cells, whole cell recordings further demonstrated that imipramine inhibited the inward Ca2+ current. Under different experimental conditions, the ionic and relaxation responses to the antidepressants were reminiscent of those mediated by the Ca2+ entry blocker verapamil. Lastly, it should be pointed out that imipramine exhibited a myorelaxant effect of similar amplitude on rat aorta and on rat distal colon. All together, these findings suggest that the myorelaxant properties of imipramine, and probably also setraline and mianserin, could result from their capacity to inhibit the voltage-sensitive Ca2+ channels. 相似文献
13.
Ana P.S. Oliveira Claure N. Lunardi Gerson J. Rodrigues Lusiane M. Bendhack 《Vascular pharmacology》2009,50(5-6):153-159
Vascular endothelium generates nitric oxide (NO) in large vessels and induces relaxation of vascular smooth muscle cells (VSMC). The aim of this study was to evaluate the contribution of NO produced in the endothelial cells (EC) to the relaxation induced by the Ca2+ ionophore A23187 and whether this relaxation is impaired in renal hypertensive (2K-1C) rat arteries. Concentration-effect curves for A23187 were constructed in intact endothelium isolated carotid rings from 2K-1C and normotensive (2K) in the absence or in the presence of the extracellular NO scavenger haemoglobin or inhibitors of NO-synthase (NOS, L-NOARG), guanylyl-cyclase (GC, ODQ). In carotid rings loaded with Fluo-3AM, both EC and VSMC were simultaneously imaged by a confocal microscope and [Ca2+]c was derived from fluorescence intensities (IF). The maximal relaxation (ME) induced by A23187 was lower in 2K-1C than in 2K arteries. A23187-induced relaxation was abolished by haemoglobin and L-NOARG in both groups. ODQ reduced the ME to A23187 in 2K and abolished its relaxation in 2K-1C. A23187 increased [Ca2+]c in a similar way in 2K and 2K-1C EC, and decreased [Ca2+]c in VSMC, which effect was higher in 2K than in 2K-1C arteries. L-NOARG inhibited the effect of A23187 in VSMC from 2K and abolished it in 2K-1C rats. On the other hand, L-NOARG did not modify the effect of A23187 in EC from 2K and 2K-1C rats.The basal content of cGMP was higher in 2K than in 2K-1C arterial rings that was similarly increased by A23187. In conclusion, the Ca2+ ionophore A23187 increases Ca2+, activates NOS and NO production in the EC activating GC in VSMC and [Ca2+]c decrease. All these effects are higher in 2K, which contribute to the impaired relaxation to A23187 in 2K-1C rat arteries. 相似文献
14.
Wang JP Chang LC Kuan YH Tsao LT Huang LJ Kuo SC 《Naunyn-Schmiedeberg's archives of pharmacology》2004,370(5):353-360
2-Benzyloxybenzaldehyde (CCY1a) inhibited the formyl-Met-Leu-Phe (fMLP)-induced elevation of cytosolic [Ca2+] ([Ca2+]i) in rat neutrophils. The late plateau phase, but not the initial Ca2+ spike, of the fMLP-induced [Ca2+]i change was inhibited by CCY1a. In the absence of external Ca2+, CCY1a had no appreciable effect on either the fMLP- or cyclopiazonic acid (CPA)-induced [Ca2+]i elevation. CCY1a failed to inhibit [Ca2+]i changes induced by N-ethylmaleimide, GEA3162, ionomycin or sphingosine, but slightly inhibited the Ca2+ signals elicited by ATP or interleukin-8 (IL-8). In a classical Ca2+ readdition protocol, addition of CCY1a after cell activation strongly inhibited the [Ca2+]i response to fMLP, whilst that to CPA was only slightly reduced. CCY1a nearly abrogated the fMLP-stimulated Mn2+ influx but was less effective on the CPA-induced response. CCY1a attenuated the levels of tyrosine-phosphorylated bands in the 70–85 kDa molecular mass range. CCY1a had no effect on the basal [Ca2+]i level, the pharmacologically isolated plasma membrane Ca2+-ATPase activity or on the mitochondrial membrane potential. Thus, CCY1a blocks fMLP-induced Ca2+ entry into neutrophils probably by blocking the relevant Ca2+ channel directly or, alternatively, indirectly through the attenuation of tyrosine phosphorylation of some cellular proteins. 相似文献
15.
Kim HJ Choi JS Lee YM Shim EY Hong SH Kim MJ Min DS Rhie DJ Kim MS Jo YH Hahn SJ Yoon SH 《Neuropharmacology》2005,49(2):265-274
Fluoxetine, a widely used antidepressant, has additional effects, including the blocking of voltage-gated ion channels. We examined whether fluoxetine affects ATP-induced calcium signaling in PC12 cells using fura-2-based digital calcium imaging, an assay for [3H]-inositol phosphates (IPs) and whole-cell patch clamping. Treatment with ATP (100 microM) for 2 min induced increases in intracellular free Ca(2+) concentrations ([Ca(2+)](i)). Treatment with fluoxetine (100 nM to 30 microM) for 5 min inhibited the ATP-induced [Ca(2+)](i) increases in a concentration-dependent manner (IC(50) = 1.85 microM). Treatment with fluoxetine (1.85 microM) for 5 min significantly inhibited the ATP-induced responses following the removal of extracellular Ca(2+) or depletion of intracellular Ca(2+) stores. Whereas treatment for 10 min with nimodipine (1 microM) significantly inhibited the ATP-induced [Ca(2+)](i) increase, treatment with fluoxetine further inhibited the ATP-induced response. Treatment with fluoxetine significantly inhibited [Ca(2+)](i) increases induced by 50 mM K(+). In addition, treatment with fluoxetine markedly inhibited ATP-induced inward currents in a concentration-dependent manner. However, treatment with fluoxetine did not inhibit ATP-induced [3H]-IPs formation. Therefore, we conclude that fluoxetine inhibits ATP-induced [Ca(2+)](i) increases in PC12 cells by inhibiting both the influx of extracellular Ca(2+) and the release of Ca(2+) from intracellular stores without affecting IPs formation. 相似文献
16.
The mechanism of honokiol-induced and magnolol-induced inhibition on muscle contraction and Ca2+ mobilization in rat uterus 总被引:4,自引:0,他引:4
Lu YC Chen HH Ko CH Lin YR Chan MH 《Naunyn-Schmiedeberg's archives of pharmacology》2003,368(4):262-269
The effects of honokiol and magnolol extracted from the Magnolia officinalis on muscular contractile responses and intracellular Ca2+ mobilization were investigated in the non-pregnant rat uterus. Honokiol and magnolol (1–100 mol/l) were observed to inhibit spontaneous and uterotonic agonists (carbachol, PGF2, and oxytocin)-, high K+-, and Ca2+ channel activator (Bay K 8644)-induced uterine contractions in a concentration-dependent manner. The inhibition rate of honokiol on spontaneous contractions appeared to be slower than that of magnolol-induced response. The time periods that were required for honokiol and magnolol, at 100 mol/l, to abolish 50% spontaneous contractions were approximately 6 min. Furthermore, honokiol and magnolol at 10 mol/l also blocked the Ca2+-dependent oscillatory contractions. Consistently, the increases in intracellular Ca2+ concentrations ([Ca2+]i) induced by PGF2 and high K+ were suppressed by both honokiol and magnolol at 10 mol/l. After washout of these treatments, the rise in [Ca2+]i induced by PGF2 and high K+ was still partially abolished. In conclusion, the inhibitory effects of honokiol and magnolol on uterine contraction may be mediated by blockade of external Ca2+ influx, leading to a decrease in [Ca2+]i. Honokiol and magnolol may be considered as putative Ca2+ channel blockers and be of potential value in the treatment of gynecological dysfunctions associated with uterine muscular spasm and dysmenorrhea. 相似文献
17.
This study investigates functional consequences of TRPC1 ion channel downregulation observed in aging rat aorta by employing RNA interference in cultured vascular smooth muscle cells. For this purpose, A7r5 aortic smooth muscle cells were used in quantitative gene and protein expression as well as in functional analyses. According to quantitative RT-PCR results, TRPC3, TRPC4 and TRPC5 mRNAs were not at detectable levels. In siTRPC1-transfected cells, TRPC1 mRNA and protein levels were decreased by 40% and 64%; however, those of TRPC6 were drastically increased by 100% and 200%, respectively. In fura-2-loaded TRPC1 knockdown cells, despite the decreased TRPC1 levels, cyclopiazonic acid-induced Ca2+ entry and store-operated Ca2+ entry following Ca2+ addition were elevated by 77% and 135%, respectively. Results suggest that decrease in TRPC1 may be compensated by upregulated TRPC6 that possibly takes part in store-operated Ca2+ entry in vascular smooth muscle cells. 相似文献
18.
Y. W. Kwon Q. Zhong X. Y. Wei W. Zheng D. J. Triggle 《Naunyn-Schmiedeberg's archives of pharmacology》1990,341(1-2):128-136
Summary The Ca2+ channel antagonistic potencies of tiamdipine [2-(2-aminoethylthio)methyl-3-carboethoxy-5-carbomethoxy-6-methyl-4-(3-nitrophenyl)-1,4-dihydropyridine] and nifedipine [2,6-dimethyl-3,5-dicarbomethoxy-4-(2nitrophenyl)-1,4-dihydropyridine] analogs bearing phenyl ring substituents were studied using pharmacologic and radioligand binding techniques. Additionally, analogs of tiamdipine possessing (2-aminoethylthio)methyl-, (2-acetamidoethylthio)methyl-and (2-pyrrolidinylmethylthio)methyl-groups at the C2 position of the 1,4-dihydropyridine ring have been studied.Tiamdipine and nifedipine analogs inhibited K+-induced contractile responses in rat tail artery. IC50 values of 4-phenyl ring substituted 2-(2-aminoethylthio)methyl tiamdipine analogs ranged from 10–7 mol/l to 10–8 mol/l. However, the corresponding 4-phenyl ring substituted nifedipine analogs covered a wider range of potency from 10–6 mol/l to 10–9 mol/l. K, values of the corresponding tiamdipine analogs for the inhibition of specific [3H]PN 200-110 [( I- ) [3H]isopropyl-4-(2,1,3-benzoxadiazol-4-yl)-1,4-dihydro-5-methoxycarbonyl-2,6-dimethyl-3-pyridinecarboxylate] binding-ranged from 10–7 mol/l to 10–9 mol/l in guinea pig ileal and rat heart membranes and rat brain synaptosomes.The two stereoisomers of tiamdipine and its analog 2-(2acetamidoethylthio)methyl-3-carboethoxy-5-carbomethoxy-6-methyl-4-(3-nitrophenyl)-1,4-dihydropyridine, and the four stereoisomers of 2-(2-pyrrolidinylmethylthio)methyl-3carboethoxy-5-carbomethoxy-6-methyl-4-(3-nitrophenyl)1,4-dihydropyridine showed high stereoselectivity ratios of approximately (–)/(+) = 100 and 1000 in pharmacologic and binding experiments, respectively.The inhibitory actions of 2-(2-aminoethylthio)methyltiamdipine analogs against K+-induced contractile responses in rat tail artery developed very slowly requiring at least 2 h for maximum effect. The recoveries of response to K+ depolarization were also correspondingly slow. However, recovery was greatly accelerated by the presence of the 1,4-dihydropyridine activator Bay K 8644 [2,6-dimethyl-3carbomethoxy-5-nitro-4-(2-trifluoromethyl)-1,4-dihydropyridine, 5 × 10–6 mol/l] immediately prior to the K+ challenge. The 2-(2-acetamidoethylthio)methyl tiamdipine derivative and nifedipine produced maximum inhibitory effects within 10 min, and responses recovered rapidly upon washing.The slow kinetics of onset and offset of action of the tiamdipine analogs and the reduced effects of 4-phenyl substitution relative to agents of the nifedipine series suggest that these two series of 1,4-dihydropyridines exhibit different modes of interaction with the Ca2+ channel. At least part of this difference is to be attributed to the presence of a charged group in the basic tiamdipine series. Trapping of these agents within the membrane phase likely contributes to their observed slow kinetics of action. 相似文献
19.
Kyung Jin Choi Jin Wook Hwang Se Hoon Kim Hyung Seo Park 《The Korean journal of physiology & pharmacology》2022,26(3):219
Glucagon like peptide-1 (GLP-1) released from enteroendocine L-cells in the intestine has incretin effects due to its ability to amplify glucose-dependent insulin secretion. Promotion of an endogenous release of GLP-1 is one of therapeutic targets for type 2 diabetes mellitus. Although the secretion of GLP-1 in response to nutrient or neural stimuli can be triggered by cytosolic Ca2+ elevation, the stimulus-secretion pathway is not completely understood yet. Therefore, the aim of this study was to investigate the role of reverse Na+/Ca2+ exchanger (rNCX) in Ca2+ entry induced by muscarinic stimulation in NCI-H716 cells, a human enteroendocrine GLP-1 secreting cell line. Intracellular Ca2+ was repetitively oscillated by the perfusion of carbamylcholine (CCh), a muscarinic agonist. The oscillation of cytosolic Ca2+ was ceased by substituting extracellular Na+ with Li+ or NMG+. KB-R7943, a specific rNCX blocker, completely diminished CCh-induced cytosolic Ca2+ oscillation. Type 1 Na+/Ca2+ exchanger (NCX1) proteins were expressed in NCI-H716 cells. These results suggest that rNCX might play a crucial role in Ca2+ entry induced by cholinergic stimulation in NCI-H716 cells, a GLP-1 secreting cell line. 相似文献
20.
Chuen Mao Yang Ying-Ling Yo Richard Ong Jen Tsung Hsieh Hui-Liang Tsao 《Naunyn-Schmiedeberg's archives of pharmacology》1994,350(1):68-76
Endothelins (ETs)- and sarafotoxin (S6b)-induced rises in intracellular Ca2+ concentration ([Ca2+]i) were monitored in cultured canine tracheal smooth muscle cells by using a fluorescent Ca2+ indicator fura-2. ET-1, ET-2, ET-3 and S6b elicited an initial transient peak and followed by a sustained elevation of [Ca2+]i, with half-maximal effect (EC50) of 18, 20, 38 and 21 nM, respectively. BQ-123, an ETA receptor antagonist, had a high affinity to block the rise in [Ca2+]i response to ET-1, ET-2, and S6b, as well as a low affinity for ET-3. Removal of external Ca2+ by addition of EGTA during the sustained phase, caused a rapid decline in [Ca2+]i to the resting level. In the absence of external Ca2+, only an initial transient peak of [Ca2+]i was seen, the sustained elevation of [Ca2+]. could then be evoked by addition of 1.8 mM Ca2+. Ca2+ influx was required for the changes of [Ca2+]i, since the Ca2+-channel blockers, diltiazem, verapamil, and Ni2+, decreased both the initial and sustained elevation of [Ca2+]i response to these peptides. ETs exhibited homologous desensitization of the Ca2+ response, but partial heterologous desensitization of the Ca2+ response mediated by carbachol to different extents. In contrast, ETs did not desensitize the Ca2+ response induced by ATP or vice versa. These data demonstrate that the initial detectable increase in [Ca2+]i stimulated by these peptides is due to the activation of ETA receptors and subsequently the release of Ca2+ from internal stores, whereas the contribution of external Ca2+ follows and partially involves a diltiazem- and verapamil-sensitive process. There is a cross-regulation among ETs and other receptor-coupling signal transduction pathways through PI hydrolysis in canine tracheal smooth muscle cells.
Correspondence to: C. Mao Yang at the above address 相似文献