| 1. |
- Alexander, Stephen P. H., et al.
(author)
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The Concise Guide to PHARMACOLOGY 2023/24: G protein-coupled receptors
- 2023
-
In: BRITISH JOURNAL OF PHARMACOLOGY. - : British pharmacological society. - 0007-1188 .- 1476-5381. ; 180
-
Journal article (peer-reviewed)abstract
- The Concise Guide to PHARMACOLOGY 2023/24 is the sixth in this series of biennial publications. The Concise Guide provides concise overviews, mostly in tabular format, of the key properties of approximately 1800 drug targets, and about 6000 interactions with about 3900 ligands. There is an emphasis on selective pharmacology (where available), plus links to the open access knowledgebase source of drug targets and their ligands (), which provides more detailed views of target and ligand properties. Although the Concise Guide constitutes almost 500 pages, the material presented is substantially reduced compared to information and links presented on the website. It provides a permanent, citable, point-in-time record that will survive database updates. The full contents of this section can be found at . G protein-coupled receptors are one of the six major pharmacological targets into which the Guide is divided, with the others being: ion channels, nuclear hormone receptors, catalytic receptors, enzymes and transporters. These are presented with nomenclature guidance and summary information on the best available pharmacological tools, alongside key references and suggestions for further reading. The landscape format of the Concise Guide is designed to facilitate comparison of related targets from material contemporary to mid-2023, and supersedes data presented in the 2021/22, 2019/20, 2017/18, 2015/16 and 2013/14 Concise Guides and previous Guides to Receptors and Channels. It is produced in close conjunction with the Nomenclature and Standards Committee of the International Union of Basic and Clinical Pharmacology (NC-IUPHAR), therefore, providing official IUPHAR classification and nomenclature for human drug targets, where appropriate.
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| 2. |
- Christopoulos, Arthur, et al.
(author)
-
THE CONCISE GUIDE TO PHARMACOLOGY 2021/22: G protein-coupled receptors.
- 2021
-
In: British journal of pharmacology. - : Wiley. - 1476-5381 .- 0007-1188. ; 178 Suppl 1
-
Research review (peer-reviewed)abstract
- The Concise Guide to PHARMACOLOGY 2021/22 is the fifth in this series of biennial publications. The Concise Guide provides concise overviews, mostly in tabular format, of the key properties of nearly 1900 human drug targets with an emphasis on selective pharmacology (where available), plus links to the open access knowledgebase source of drug targets and their ligands (www.guidetopharmacology.org), which provides more detailed views of target and ligand properties. Although the Concise Guide constitutes over 500 pages, the material presented is substantially reduced compared to information and links presented on the website. It provides a permanent, citable, point-in-time record that will survive database updates. The full contents of this section can be found at http://onlinelibrary.wiley.com/doi/bph.15538. G protein-coupled receptors are one of the six major pharmacological targets into which the Guide is divided, with the others being: ion channels, nuclear hormone receptors, catalytic receptors, enzymes and transporters. These are presented with nomenclature guidance and summary information on the best available pharmacological tools, alongside key references and suggestions for further reading. The landscape format of the Concise Guide is designed to facilitate comparison of related targets from material contemporary to mid-2021, and supersedes data presented in the 2019/20, 2017/18, 2015/16 and 2013/14 Concise Guides and previous Guides to Receptors and Channels. It is produced in close conjunction with the Nomenclature and Standards Committee of the International Union of Basic and Clinical Pharmacology (NC-IUPHAR), therefore, providing official IUPHAR classification and nomenclature for human drug targets, where appropriate.
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| 3. |
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| 4. |
- Ammoun, Sylwia, et al.
(author)
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Distinct Recognition of OX1 and OX2 Receptors by Orexin Peptides
- 2003
-
In: Journal of Pharmacology and Experimental Therapeutics. - : American Society for Pharmacology & Experimental Therapeutics (ASPET). - 0022-3565 .- 1521-0103. ; 305:2, s. 507-514
-
Journal article (peer-reviewed)abstract
- In this study, we have compared the abilities of orexin-A and orexin-B and variants of orexin-A to activate different Ca(2+) responses (influx and release) in human OX(1) and OX(2) receptor- expressing Chinese hamster ovary cells. Responses mediated by activation of both receptor subtypes with either orexin-A or -B were primarily dependent on extracellular Ca(2+), suggesting similar activation of Ca(2+) influx as we have previously shown for orexin-A and OX(1) receptors. Amino acid-wise truncation of orexin-A reduced its ability to activate OX(1) and OX(2) receptors, but the response mediated by the OX(2) receptor was more resistant to truncation than the response mediated by the OX(1) receptor. We also performed a sequential replacement of amino acids 14 to 26 with alanine in the truncated orexin-A variant orexin-A(14-33). Replacement of the same amino acids produced a fall in the potency for each receptor subtype, but the reduction was less prominent for the OX(2) receptor. The most marked reduction was produced by the replacement of Leu20, Asp25, and His26 with alanine. Interestingly, extracellular Ca(2+) dependence of responses to some of the mutated peptides was different from those of orexin-A and -B. The mutagenesis also suggests that although the determinants required from orexin-A for binding to and activation of the receptor are highly conserved between the orexin receptor subtypes, the OX(2) receptor requires fewer determinants. This might in part explain why orexin-B has the affinity and potency equal to orexin-A for this subtype, although it has 10- to 100-fold lower affinity and potency for the OX(1) receptor.
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| 5. |
- Ammoun, Sylwia, et al.
(author)
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G-protein-coupled OX1 Orexin/hcrtr-1 Hypocretin Receptors Induce Caspase-dependent and -independent Cell Death through p38 Mitogen-/Stress-activated Protein Kinase
- 2006
-
In: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 281, s. 834-842
-
Journal article (peer-reviewed)abstract
- We have investigated the signaling of OX1 receptors to cell death using Chinese hamster ovary cells as a model system. OX1 receptor stimulation with orexin-A caused a delayed cell death independently of cytosolic Ca2+ elevation. The classical mitogen-activated protein kinase (MAPK) pathways, ERK and p38, were strongly activated by orexin-A. p38 was essential for induction of cell death, whereas the ERK pathway appeared protective. A pathway often implicated in the p38-mediated cell death, activation of p53, did not mediate the cell death, as there was no stabilization of p53 or increase in p53-dependent transcriptional activity, and dominant-negative p53 constructs did not inhibit cell demise. Under basal conditions, orexin-A-induced cell death was associated with compact chromatin condensation and it required de novo gene transcription and protein synthesis, the classical hallmarks of programmed (apoptotic) cell death. However, though the pan-caspase inhibitor N-benzyloxycarbonyl-Val-Ala-Asp-(O-methyl)fluoromethyl ketone (Z-VAD-fmk) fully inhibited the caspase activity, it did not rescue the cells from orexin-A-induced death. In the presence of Z-VAD-fmk, orexin-A-induced cell death was still dependent on p38 and de novo protein synthesis, but it no longer required gene transcription. Thus, caspase inhibition causes activation of alternative, gene transcription-independent death pathway. In summary, the present study points out mechanisms for orexin receptor-mediated cell death and adds to our general understanding of the role of G-protein-coupled receptor signaling in cell death by suggesting a pathway from G-protein-coupled receptors to cell death via p38 mitogen-/stress-activated protein kinase independent of p53 and caspase activation.
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| 6. |
- Ammoun, Sylwia, et al.
(author)
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OX1 orexin receptors activate extracellular signal-regulated kinase in Chinese hamster ovary cells via multiple mechanisms : the role of Ca2+ influx in OX1 receptor signaling
- 2006
-
In: Molecular Endocrinology. - : The Endocrine Society. - 0888-8809 .- 1944-9917. ; 20:1, s. 80-99
-
Journal article (peer-reviewed)abstract
- Activation of OX1 orexin receptors heterologously expressedin Chinese hamster ovary (CHO) cells led to a rapid, strong,and long-lasting increase in ERK phosphorylation (activation).Dissection of the signal pathways to ERK using multiple inhibitorsand dominant-negative constructs indicated involvement of Ras,protein kinase C, phosphoinositide-3-kinase, and Src. Most interestingly,Ca2+ influx appeared central for the ERK response in CHO cells,and the same was indicated in recombinant neuro-2a cells andcultured rat striatal neurons. Detailed investigations in CHOcells showed that inhibition of the receptor- and store-operatedCa2+ influx pathways could fully attenuate the response, whereasinhibition of the store-operated Ca2+ influx pathway alone orthe Ca2+ release was ineffective. If the receptor-operated pathwaywas blocked, an exogenously activated store-operated pathwaycould take its place and restore the coupling of OX1 receptorsto ERK. Further experiments suggested that Ca2+ influx, as such,may not be required for ERK phosphorylation, but that Ca2+,elevated via influx, acts as a switch enabling OX1 receptorsto couple to cascades leading to ERK phosphorylation, cAMP elevation,and phospholipase C activation. In conclusion, the data suggestthat the primary coupling of orexin receptors to Ca2+ influxallows them to couple to other signal pathways; in the absenceof coupling to Ca2+ influx, orexin receptors can act as signalintegrators by taking advantage of other Ca2+ influx pathways.
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| 7. |
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| 8. |
- Ekholm, Marie E., et al.
(author)
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IP3-independent signalling of OX1 orexin/hypocretin receptors to Ca2+ influx and ERK
- 2007
-
In: Biochemical and Biophysical Research Communications - BBRC. - : Elsevier BV. - 0006-291X .- 1090-2104. ; 353:2, s. 475-480
-
Journal article (peer-reviewed)abstract
- OX1 orexin receptors (OX1R) have been shown to activate receptor-operated Ca2+ influx pathways as their primary signalling pathway; however, investigations are hampered by the fact that orexin receptors also couple to phospholipase C, and therewith inositol-1,4,5-trisphosphate (IP3)-dependent Ca2+ release. We have here devised a method to block the latter signalling in order to focus on the mechanism of Ca2+ influx activation by OX1R in recombinant systems. Transient expression of the IP3-metabolising enzymes IP3-3-kinase-A (inositol-1,4,5-trisphosphate → inositol-1,3,4,5-tetrakisphosphate) and type I IP3-5-phosphatase (inositol-1,4,5-trisphosphate → inositol-1,4-bisphosphate) almost completely attenuated the OX1R-stimulated IP3 elevation and Ca2+ release from intracellular stores. Upon attenuation of the IP3-dependent signalling, the receptor-operated Ca2+ influx pathway became the only source for Ca2+ elevation, enabling mechanistic studies on the receptor-channel coupling. Attenuation of the IP3 elevation did not affect the OX1R-mediated ERK (extracellular signal-regulated kinase) activation in CHO cells, which supports our previous finding of the major importance of receptor-operated Ca2+ influx for this response.
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| 9. |
- Ekholm, Marie, et al.
(author)
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Rapid and easy semi-quantitative evaluation method for diacylglycerol and inositol-1,4,5-trisphosphate generation in orexin receptor signalling
- 2010
-
In: Acta Physiologica. - : Wiley. - 1748-1708 .- 1748-1716. ; 198:3, s. 387-392
-
Journal article (peer-reviewed)abstract
- Aim: Fluorescent protein-based indicators have enabled measurement of intracellular signals previously nearly inaccessible for studies. However, indicators showing intracellular translocation upon response suffer from serious limitations, especially the very time-consuming data collection. We therefore set out in this study to evaluate whether fixing and counting cells showing translocation could mend this issue. Methods: Altogether three different genetically encoded indicators for diacylglycerol and inositol-1,4,5-trisphosphate were transiently expressed in Chinese hamster ovary cells stably expressing human OX1 orexin receptors. Upon stimulation with orexin-A, the cells were fixed with six different protocols. Results: Different protocols showed clear differences in their ability to preserve the indicator’s localization (i.e. translocation after stimulus) and its fluorescence, and the best results for each indicator were obtained with a different protocol. The concentration Conclusion: The counting method, as used here, works at single time point and looses the single-cell-quantitative aspect. However, it also has some useful properties. First, it easily allows processing of a 100- to 1000-fold higher cell numbers than real-time imaging producing statistically consistent population-quantitative data much faster. Secondly, it does not require expensive real-time imaging equipment. Fluorescence in fixed cells can also be quantitated, though this analysis would be more time-consuming than cell counting. Thirdly, in addition to the quantitative data collection, the method could be applied for identifying responsive cells. This might be very useful in identification of e.g. orexin-responding neurones in a large population of non-responsive cells in primary cultures.
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| 10. |
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| 11. |
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| 12. |
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| 13. |
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| 14. |
- Holmqvist, Tomas, et al.
(author)
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OX1 orexin receptors couple to adenylyl cyclase regulation via multiple mechanisms
- 2005
-
In: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 280:8, s. 6570-6579
-
Journal article (peer-reviewed)abstract
- In this study, the mechanism of OX(1) orexin receptors to regulate adenylyl cyclase activity when recombinantly expressed in Chinese hamster ovary cells was investigated. In intact cells, stimulation with orexin-A led to two responses, a weak (21%), high potency (EC(50) approximately 1 nm) inhibition and a strong (4-fold), low potency (EC(50) = approximately 300 nm) stimulation. The inhibition was reversed by pertussis toxin, suggesting the involvement of G(i/o) proteins. Orexin-B was, surprisingly, almost equally as potent as orexin-A in elevating cAMP (pEC(50) = approximately 500 nm). cAMP elevation was not caused by Ca(2+) elevation or by Gbetagamma. In contrast, it relied in part on a novel protein kinase C (PKC) isoform, PKCdelta, as determined using pharmacological inhibitors. Yet, PKC stimulation alone only very weakly stimulated cAMP production (1.1-fold). In the presence of G(s) activity, orexins still elevated cAMP; however, the potencies were greatly increased (EC(50) of orexin-A = approximately 10 nm and EC(50) of orexin-B = approximately 100 nm), and the response was fully dependent on PKCdelta. In permeabilized cells, only a PKC-independent low potency component was seen. This component was sensitive to anti-Galpha(s) antibodies. We conclude that OX(1) receptors stimulate adenylyl cyclase via a low potency G(s) coupling and a high potency phospholipase C --> PKC coupling. The former or some exogenous G activation is essentially required for the PKC to significantly activate adenylyl cyclase. The results also suggest that orexin-B-activated OX(1) receptors couple to G(s) almost as efficiently as the orexin-A-activated receptors, in contrast to Ca(2+) elevation and phospholipase C activation, for which orexin-A is 10-fold more potent.
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| 15. |
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| 16. |
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| 17. |
- Johansson, Lisa, et al.
(author)
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Regulation of OX1 orexin/hypocretin receptor-coupling to phospholipase C by Ca2+ influx
- 2007
-
In: British Journal of Pharmacology. - : Wiley. - 0007-1188 .- 1476-5381. ; 150:1, s. 97-104
-
Journal article (peer-reviewed)abstract
- Background and purpose: Orexin (OX) receptors induce Ca2+ elevations via both receptor-operated Ca2+ channels (ROCs) and the "conventional" phospholipase C (PLC)-Ca2+ release-store-operated Ca2+ channel (SOC) pathways. In this study we assessed the ability of these different Ca2+ influx pathways to amplify OX, receptor signalling to PLC in response to stimulation with the physiological ligand orexin-A. Experimental approach: PLC activity was assessed in CHO cells stably expressing human OX1 receptors. Key results: Inhibition of total Ca2+ influx by reduction of the extracellular [Ca2+] to 1 mu M effectively inhibited the receptor-stimulated PLC activity at low orexin-A concentrations (by 93% at 1 nM), and this effect was gradually reduced by higher orexin-A concentrations. A similar but weaker inhibitory effect (84% at 1 nM) was obtained on depolarization to similar to 0 mV, which disrupts most of the driving force for Ca2+ entry. The inhibitor of the OX, receptor-activated ROCs, tetraethylammonium chloride (TEA), was somewhat less effective than the reduction in extracellular [Ca2+] at inhibiting PLC activation, probably because it only partially blocks ROCs. The partial inhibitor of both ROCs and SOCs, Mg2+, and the SOC inhibitors, dextromethorphan, SKF-96365 (1-[beta-(3-(4-methoxyphenyl)propoxy)-4-methoxyphenethyl]-1H-imidazole HCl) and 2-APB (2-aminoethoxydiphenyl borate), inhibited PLC activity at low concentrations of orexin-A, but were not as effective as TEA. Conclusions and implications: Both ROCs and SOCs markedly amplify the OX1 receptor-induced PLC response, but ROCS are more central for this response. These data indicate the crucial role of ROCs in orexin receptor signalling.
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| 18. |
- Kairisalo, Minna, et al.
(author)
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NF-kappaB-dependent regulation of brain-derived neurotrophic factor in hippocampal neurons by X-linked inhibitor of apoptosis protein.
- 2009
-
In: The European journal of neuroscience. - : Wiley. - 1460-9568 .- 0953-816X. ; 30:6, s. 958-66
-
Journal article (peer-reviewed)abstract
- X chromosome-linked inhibitor of apoptosis protein (XIAP) is an anti-apoptotic protein enhancing cell survival. Brain-derived neurotrophic factor (BDNF) also promotes neuronal viability but the links between XIAP and BDNF have remained unclear. We show here that the overexpression of XIAP increases BDNF in transgenic mice and cultured rat hippocampal neurons, whereas downregulation of XIAP by silencing RNA decreased BDNF. XIAP also stimulated BDNF signaling, as shown by increased phosphorylation of the TrkB receptor and the downstream molecule, cAMP response element-binding protein. The mechanism involved nuclear factor-kappaB (NF-kappaB) activation and blocking of NF-kappaB signaling inhibited the increased activities of BDNF promoters I and IV by XIAP. In neuronal cultures XIAP also upregulated interleukin (IL)-6, which is an NF-kappaB-responsive gene. The addition of IL-6 elevated whereas incubation with IL-6-blocking antibodies reduced BDNF in the neurons. BDNF itself activated NF-kappaB in the neurons at higher concentrations. The data show that XIAP has trophic effects on hippocampal neurons by increasing BDNF and TrkB activity. The results reveal a cytokine network in the brain involving BDNF, IL-6 and XIAP interconnected via the NF-kappaB system.
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| 19. |
- Kukkonen, Jyrki P
(author)
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An easy ratiometric compensation for the extracellular Ca2+ indicator-caused fluorescence artifact
- 2009
-
In: Analytical Biochemistry. - : Elsevier BV. - 0003-2697 .- 1096-0309. ; 390:2, s. 212-214
-
Journal article (peer-reviewed)abstract
- Measurement of intracellular Ca(2+) dynamics is one of the most central real-time assays for cellular signaling. Ratiometric methods reduce the need for internal calibration and also effectively compensate for most artifacts when used in imaging. However, ratiometric calculation cannot compensate for extracellularly leaked (and fluorescent) Ca(2+) indicator and will instead indicate erroneous Ca(2+) concentration. This frequently occurs in systems where extracellular indicator is accumulated such as fluorescence spectrophotometers and plate readers. Here I present a method that, for the first time, fully compensates for this phenomenon. The method uses a single-step internal calibration together with a predefined ratiometric calibration protocol.
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| 20. |
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| 21. |
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| 22. |
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| 23. |
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| 24. |
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| 25. |
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| 26. |
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| 27. |
- Lagerström, Malin C., et al.
(author)
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Origin of the prolactin-releasing hormone (PRLH) receptors : Evidence of coevolution between PRLH and a redundant neuropeptide Y receptor during vertebrate evolution
- 2005
-
In: Genomics. - : Elsevier BV. - 0888-7543 .- 1089-8646. ; 85:6, s. 688-703
-
Journal article (peer-reviewed)abstract
- We present seven new vertebrate homologs of the prolactin-releasing hormone receptor (PRLHR) and show that these are found as two separate subtypes, PRLHR1 and PRLHR2. Analysis of a number of vertebrate sequences using phylogeny, pharmacology, and paralogon analysis indicates that the PRLHRs are likely to share a common ancestry with the neuropeptide Y (NPY) receptors. Moreover, a micromolar level of NPY was able to bind and inhibit completely the PRLH-evoked response in PRLHR1-expressing cells. We suggest that an ancestral PRLH peptide started coevolving with a redundant NPY binding receptor, which then became PRLHR, approximately 500 million years ago. The PRLHR1 subtype was shown to have a relatively high evolutionary rate compared to receptors with fixed peptide preference, which could indicate a drastic change in binding preference, thus supporting this hypothesis. This report suggests how gene duplication events can lead to novel peptide ligand/receptor interactions and hence spur the evolution of new physiological functions.
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| 28. |
- Larsson, Kim P, et al.
(author)
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Orexin-A-induced Ca2+ entry : evidence for involvement of trpc channels and protein kinase C regulation.
- 2005
-
In: J Biol Chem. - 0021-9258. ; 280:3, s. 1771-81
-
Journal article (peer-reviewed)abstract
- The orexins are peptide transmitters/hormones, which exert stimulatory actions in many types of cells via the G-protein-coupled OX(1) and OX(2) receptors. Our previous results have suggested that low (subnanomolar) concentrations of orexin-A activate Ca(2+) entry, whereas higher concentrations activate phospholipase C, Ca(2+) release, and capacitative Ca(2+) entry. As shown here, the Ca(2+) response to subnanomolar orexin-A concentrations was blocked by activation of protein kinase C by using different approaches (12-O-tetradecanoylphorbol acetate, dioctanoylglycerol, and diacylglycerol kinase inhibition) and protein phosphatase inhibition by calyculin A. The Ca(2+) response to subnanomolar orexin-A concentrations was also blocked by Mg(2+), dextromethorphan, and tetraethylammonium. These treatments neither affected the response to high concentrations of orexin-A nor the thapsigargin-stimulated capacitative entry. The capacitative entry was instead strongly suppressed by SKF96365. An inward membrane current activated by subnanomolar concentrations of orexin-A and the currents activated upon transient expression of trpc3 channels were also sensitive to Mg(2+), dextromethorphan, and tetraethylammonium. Responses to subnanomolar concentrations of orexin-A (Ca(2+) elevation, inward current, and membrane depolarization) were voltage-dependent with a loss of the response around -15 mV. By using reverse transcription-PCR, mRNA for the trpc1-4 channel isoforms were detected in the CHO-hOX1-C1 cells. The expression of truncated TRPC channel isoforms, in particular trpc1 and trpc3, reduced the response to subnanomolar concentrations of orexin-A but did not affect the response to higher concentrations of orexin-A. The results suggest that activation of the OX(1) receptor leads to opening of a Ca(2+)-permeable channel, involving trpc1 and -3, which is controlled by protein kinase C.
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| 29. |
- Lind, Ulrika, et al.
(author)
-
Octopamine receptors from the barnacle balanus improvisus are activated by the alpha2-adrenoceptor agonist medetomidine.
- 2010
-
In: Molecular pharmacology. - : American Society for Pharmacology & Experimental Therapeutics (ASPET). - 1521-0111 .- 0026-895X. ; 78:2, s. 237-48
-
Journal article (peer-reviewed)abstract
- G protein-coupled octopamine receptors of insects and other invertebrates represent counterparts of adrenoceptors in vertebrate animals. The alpha(2)-adrenoceptor agonist medetomidine, which is in clinical use as a veterinary sedative agent, was discovered to inhibit the settling process of barnacles, an important step in the ontogeny of this crustacean species. Settling of barnacles onto ship hulls leads to biofouling that has many harmful practical consequences, and medetomidine is currently under development as a novel type of antifouling agent. We now report that medetomidine induces hyperactivity in the barnacle larvae to disrupt the settling process. To identify the molecular targets of medetomidine, we cloned five octopamine receptors from the barnacle Balanus improvisus. We show by phylogenetic analyses that one receptor (BiOctalpha) belongs to the alpha-adrenoceptor-like subfamily, and the other four (BiOctbeta-R1, BiOctbeta-R2, BiOctbeta-R3, and BiOctbeta-R4) belong to the beta-adrenoceptor-like octopamine receptor subfamily. Phylogenetic analyses also indicated that B. improvisus has a different repertoire of beta-adrenoceptor-like octopamine receptors than insects. When expressed in CHO cells, the cloned receptors were activated by both octopamine and medetomidine, resulting in increased intracellular cAMP or calcium levels. Tyramine activated the receptors but with much lesser potency than octopamine. A hypothesis for receptor discrimination between tyramine and octopamine was generated from a homology three-dimensional model. The characterization of B. improvisus octopamine receptors is important for a better functional understanding of these receptors in crustaceans as well as for practical applications in development of environmentally sustainable antifouling agents.
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| 30. |
- Makela, Johanna, et al.
(author)
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Peroxisome proliferator-activated receptor-gamma (PPAR gamma) agonist is neuroprotective and stimulates PGC-1 alpha expression and CREB phosphorylation in human dopaminergic neurons
- 2016
-
In: Neuropharmacology. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0028-3908 .- 1873-7064. ; 102, s. 266-275
-
Journal article (peer-reviewed)abstract
- Mitochondrial dysfunction has been linked to several neurodegenerative diseases such as Parkinson's disease (PD). Peroxisome proliferator-activated receptor-gamma coactivator-1 alpha (PGC-1 alpha) is a master gene for mitochondrial biogenesis and has been shown to be neuroprotective in models of PD. In this work we have studied the mechanisms by which peroxisome proliferator-activated receptor-gamma (PPAR gamma) selective agonist N-(2-benzoylphenyl)-O-[2-(methyl-2-pyridinylamino)ethyl]-L-tyrosine hydrate (GW1929) acts on human dopaminergic neurons in culture. Data showed that GW1929 increased the viability of human dopaminergic neurons and protected them against oxidative stress induced by H2O2 and the mitochondrial toxin Rotenone. The enhanced resilience of the neurons was attributed to increased levels of mitochondrial antioxidants and of PGC-1 alpha. GW1929 treatment further increased cell respiration, mitochondrial biogenesis and sirtuin-1 (SIRT1) expression in the human dopaminergic neurons. Phosphorylation of cAMP responsive element-binding protein (CREB) was also robustly increased in GW1929-treated cells. Together these results show that the PPAR gamma agonist GW1929 influences CREB signaling and PGC-1 alpha activities in the human dopaminergic neurons contributing to an increased cell viability. This supports the view that drugs acting on the PPAR gamma-PGC-1 alpha signaling in neurons may have beneficial effects in PD and possible also in other brain disorders. (c) 2015 Elsevier Ltd. All rights reserved.
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| 31. |
- Mercer, Eric A, et al.
(author)
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NAIP interacts with hippocalcin and protects neurons against calcium-induced cell death through caspase-3-dependent and -independent pathways
- 2000
-
In: EMBO Journal. - Univ Uppsala, Biomed Ctr, Dept Neurosci, Uppsala, Sweden. Univ Uppsala, Dept Physiol, Div Cellular Physiol, S-75123 Uppsala, Sweden. : Oxford University Press. - 0261-4189 .- 1460-2075. ; 19:14, s. 3597-3607
-
Journal article (peer-reviewed)abstract
- Inhibitor-of-apoptosis proteins (IAPs), including neuronal apoptosis inhibitory protein (NAIP), inhibit cell death. Other IAPs inhibit key caspase proteases which effect cell death, but the mechanism by which NAIP acts is unknown. Here we report that NAIP, through its third baculovirus inhibitory repeat domain (BIR3), binds the neuron-restricted calcium-binding protein, hippocalcin, in an interaction promoted by calcium. In neuronal cell lines NSC-34 and Neuro-2a, over-expression of the BIR domains of NAIP (NAIP-BIR1-3) counteracted the calcium-induced cell death induced by ionomycin and thapsigargin. This protective capacity was significantly enhanced when NAIP-BIR1-3 was co-expressed with hippocalcin. Over-expression of the BIR3 domain or hippocalcin alone did not substantially enhance cell survival, but co-expression greatly increased their protective effects. These data suggest synergy between NAIP and hippocalcin in facilitating neuronal survival against calcium-induced death stimuli mediated through the BIR3 domain. Analysis of caspase activity after thapsigargin treatment revealed that caspase-3 is activated in NSC-34, but not Neuro-2a, cells, Thus NAIP, in conjunction with hippocalcin, can protect neurons against calcium-induced cell death in caspase-3-activated and non-activated pathways.
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| 32. |
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| 33. |
- Pham, Dan Duc, et al.
(author)
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p75 Neurotrophin Receptor Signaling Activates Sterol Regulatory Element-binding Protein-2 in Hepatocyte Cells via p38 Mitogen-activated Protein Kinase and Caspase-3
- 2016
-
In: Journal of Biological Chemistry. - : AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC. - 0021-9258 .- 1083-351X. ; 291:20, s. 10747-10758
-
Journal article (peer-reviewed)abstract
- Nerve growth factor (NGF) influences the survival and differentiation of a specific population of neurons during development, but its role in non-neuronal cells has been less studied. We observed here that NGF and its pro-form, pro-NGF, are elevated in fatty livers from leptin-deficient mice compared with controls, concomitant with an increase in low density lipoprotein receptors (LDLRs). Stimulation of mouse primary hepatocytes withNGFor pro-NGF increased LDLR expression through the p75 neurotrophin receptor (p75NTR). Studies using Huh7 human hepatocyte cells showed that the neurotrophins activate the sterol regulatory element-binding protein-2 (SREBP2) that regulates genes involved in lipid metabolism. The mechanisms for this were related to stimulation of p38 mitogen-activated protein kinase (p38 MAPK) and activation of caspase-3 and SREBP2 cleavage following NGF and pro-NGF stimulations. Cell fractionation experiments showed that caspase-3 activity was increased particularly in the membrane fraction that harbors SREBP2 and caspase-2. Experiments showed further that caspase-2 interacts with pro-caspase-3 and that p38 MAPK reduced this interaction and caused caspase-3 activation. Because of the increased caspase-3 activity, the cells did not undergo cell death following p75NTR stimulation, possibly due to concomitant activation of nuclear factor-kappa B (NF-kappa B) pathway by the neurotrophins. These results identify a novel signaling pathway triggered by ligand-activated p75NTR that via p38MAPK and caspase-3 mediate the activation of SREBP2. This pathway may regulate LDLRs and lipid uptake particularly after injury or during tissue inflammation accompanied by an increased production of growth factors, including NGF and pro-NGF.
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| 34. |
- Putkonen, Noora, et al.
(author)
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Involvement of cyclin-dependent kinase-5 in the kainic acid-mediated degeneration of glutamatergic synapses in the rat hippocampus
- 2011
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In: European Journal of Neuroscience. - : WILEY-BLACKWELL. - 0953-816X .- 1460-9568. ; 34:8, s. 1212-1221
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Journal article (peer-reviewed)abstract
- Increased levels of glutamate causing excitotoxic damage accompany neurological disorders such as ischemia/stroke, epilepsy and some neurodegenerative diseases. Cyclin-dependent kinase-5 (Cdk5) is important for synaptic plasticity and is deregulated in neurodegenerative diseases. However, the mechanisms by which kainic acid (KA)-induced excitotoxic damage involves Cdk5 in neuronal injury are not fully understood. In this work, we have thus studied involvement of Cdk5 in the KA-mediated degeneration of glutamatergic synapses in the rat hippocampus. KA induced degeneration of mossy fiber synapses and decreased glutamate receptor (GluR)6/7 and post-synaptic density protein 95 (PSD95) levels in rat hippocampus in vivo after intraventricular injection of KA. KA also increased the cleavage of Cdk5 regulatory protein p35, and Cdk5 phosphorylation in the hippocampus at 12 h after treatment. Studies with hippocampal neurons in vitro showed a rapid decline in GluR6/7 and PSD95 levels after KA treatment with the breakdown of p35 protein and phosphorylation of Cdk5. These changes depended on an increase in calcium as shown by the chelators 1,2-bis(o-aminophenoxy)ethane-N,N,N?',N'-tetraacetic acid acetoxymethyl ester (BAPTA-AM) and glycol-bis (2-aminoethylether)-N,N,N?',N?'-tetra-acetic acid. Inhibition of Cdk5 using roscovitine or employing dominant-negative Cdk5 and Cdk5 silencing RNA constructs counteracted the decreases in GluR6/7 and PSD95 levels induced by KA in hippocampal neurons. The dominant-negative Cdk5 was also able to decrease neuronal degeneration induced by KA in cultured neurons. The results show that Cdk5 is essentially involved in the KA-mediated alterations in synaptic proteins and in cell degeneration in hippocampal neurons after an excitotoxic injury. Inhibition of pathways activated by Cdk5 may be beneficial for treatment of synaptic degeneration and excitotoxicity observed in various brain diseases.
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| 35. |
- Putula, Jaana, et al.
(author)
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Agonist ligand discrimination by the two orexin receptors depends on the expression system
- 2011
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In: Neuroscience Letters. - : Elsevier BV. - 0304-3940 .- 1872-7972. ; 494:1, s. 57-60
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Journal article (peer-reviewed)abstract
- Despite the recent successes in producing orexin receptor subtype-selective antagonists, these are not commonly available, and therefore, agonist ligands are regularly used to ascribe cell and tissue responses to OX(1) or OX(2) receptors. In the current study, we have compared the native "subtype-selective" agonist, orexin-B, and its reputedly enhanced synthetic variant, Ala(11), d-Leu(15)-orexin-B, in two different recombinant cell lines. Ca(2+) elevation was used as readout, and the two "selective" ligands were compared to the subtype-non-selective orexin-A, as is customary with these ligands. In transiently transfected HEK-293 cells, orexin-B showed 9-fold selectivity for the OX(2) receptor and Ala(11), d-Leu(15)-orexin-B 23-fold selectivity, when the potency ratios of ligands were compared between OX(1) and OX(2). In stable CHO-K1 cells, the corresponding values were only 2.6- and 14-fold, respectively. In addition to being low, the selectivity of the ligands was also variable, as indicated by the comparison of the two cell lines. For instance, the relative potency of Ala(11), d-Leu(15)-orexin-B at OX(2) in CHO cells was only 2.3-fold higher than its relative potency at OX(1) in HEK-293 cells; this indicates that Ala(11), d-Leu(15)-orexin-B does not show high enough selectivity for OX(2) to be useful for determination of receptor subtype expression. Comparison of the potencies of orexin-A and -B with respect to a number of published responses in OX(1)-expressing CHO cells, demonstrates that these show great variation: i.e., orexin-A is 1.6-18-fold more potent than orexin-B, depending on the response assessed. These data together suggest that orexin receptor ligands show signal trafficking, which makes agonist-based pharmacology unreliable.
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| 36. |
- Putula, Jaana, et al.
(author)
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Orexin/hypocretin receptor chimaeras reveal structural features important for orexin peptide distinction
- 2011
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In: FEBS Letters. - : Wiley. - 0014-5793 .- 1873-3468. ; 585:9, s. 1368-1374
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Journal article (peer-reviewed)abstract
- We wanted to analyze the basis for the distinction between OX(1) and OX(2) orexin receptors by the known agonists, orexin-A, orexin-B and Ala(11), d-Leu(15)-orexin-B, of which the latter two show some selectivity for OX(2). For this, chimaeric OX(1)/OX(2) and OX(2)/OX(1) orexin receptors were generated. The receptors were transiently expressed in HEK-293 cells, and potencies of the agonists to elicit cytosolic Ca(2+) elevation were measured. The results show that the N-terminal regions of the receptor are most important, and the exchange of the area from the C-terminal part of the transmembrane helix 2 to the transmembrane helix 4 is enough to lead to an almost total change of the receptor's ligand profile.
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| 37. |
- Reijonen, Sami, et al.
(author)
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Downregulation of NF-kappa B signaling by mutant huntingtin proteins induces oxidative stress and cell death
- 2010
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In: Cellular and Molecular Life Sciences (CMLS). - : SPRINGER BASEL AG. - 1420-682X .- 1420-9071. ; 67:11, s. 1929-1941
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Journal article (peer-reviewed)abstract
- Accumulation of abnormal proteins and endoplasmic reticulum stress accompany neurodegenerative diseases including Huntington's disease. We show that the expression of mutant huntingtin proteins with extended polyglutamine repeats differentially affected endoplasmic reticulum signaling cascades linked to the inositol-requiring enzyme-1 (IRE1) pathway. Thus, the p38 and c-Jun N-terminal kinase pathways were activated, while the levels of the nuclear factor-kappa B-p65 (NF-kappa B-p65) protein decreased. Downregulation of NF-kappa B signaling was linked to decreased antioxidant levels, increased oxidative stress, and enhanced cell death. Concomitantly, calpain was activated, and treatment with calpain inhibitors restored NF-kappa B-p65 levels and increased cell viability. The calpain regulator, calpastatin, was low in cells expressing mutant huntingtin, and overexpression of calpastatin counteracted the deleterious effects caused by N-terminal mutant huntingtin proteins. These results show that calpastatin and an altered NF-kappa B-p65 signaling are crucial factors involved in oxidative stress and cell death mediated by mutant huntingtin proteins.
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| 38. |
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| 39. |
- Rostami, Jinar, et al.
(author)
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Prolyl oligopeptidase inhibition by KYP-2407 increases alpha-synuclein fibril degradation in neuron-like cells
- 2020
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In: Biomedicine and Pharmacotherapy. - : Elsevier BV. - 0753-3322 .- 1950-6007. ; 131
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Journal article (peer-reviewed)abstract
- Growing evidence emphasizes insufficient clearance of pathological alpha-synuclein (αSYN) aggregates in the progression of Parkinson's disease (PD). Consequently, cellular degradation pathways represent a potential therapeutic target. Prolyl oligopeptidase (PREP) is highly expressed in the brain and has been suggested to increase αSYN aggregation and negatively regulate the autophagy pathway. Inhibition of PREP with a small molecule inhibitor, KYP-2407, stimulates autophagy and reduces the oligomeric species of αSYN aggregates in PD mouse models. However, whether PREP inhibition has any effects on intracellular αSYN fibrils has not been studied before. In this study, the effect of KYP2407 on αSYN preformed fibrils (PFFs) was tested in SH-SY5Y cells and human astrocytes. Immunostaining analysis revealed that both cell types accumulated αSYN PFFs intracellularly but KYP-2047 decreased intracellular αSYN deposits only in SH-SY5Y cells, as astrocytes did not show any PREP activity. Western blot analysis confirmed the reduction of high molecular weight αSYN species in SH-SY5Y cell lysates, and secretion of αSYN from SH-SY5Y cells also decreased in the presence of KYP-2407. Accumulation of αSYN inside the SH-SY5Y cells resulted in an increase of the auto-lysosomal proteins p62 and LC3BII, as well as calpain 1 and 2, which have been shown to be associated with PD pathology. Notably, treatment with KYP-2407 significantly reduced p62 and LC3BII levels, indicating an increased autophagic flux, and calpain 1 and 2 levels returned to normal in the presence of KYP-2407. Our findings indicate that PREP inhibition can potentially be used as therapy to reduce the insoluble intracellular αSYN aggregates.
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| 40. |
- Turunen, Pauli M, et al.
(author)
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Arachidonic acid release mediated by OX1 orexin receptors
- 2010
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In: British Journal of Pharmacology. - : Wiley. - 0007-1188 .- 1476-5381. ; 159:1, s. 212-221
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Journal article (peer-reviewed)abstract
- Background and purpose: We have previously shown that lipid mediators, produced by phospholipase D and C, are generated in OX1 orexin receptor signalling with high potency, and presumably mediate some of the physiological responses to orexin. In this study, we investigated whether the ubiquitous phospholipase A2 (PLA2) signalling system is also involved in orexin receptor signalling.Experimental approach: Recombinant Chinese hamster ovary-K1 cells, expressing human OX1 receptors, were used as a model system. Arachidonic acid (AA) release was measured from 3H-AA-labelled cells. Ca2+ signalling was assessed using single-cell imaging.Key results: Orexins strongly stimulated [3H]-AA release (maximally 4.4-fold). Orexin-A was somewhat more potent than orexin-B (pEC50= 8.90 and 8.38 respectively). The concentration2013response curves appeared biphasic. The release was fully inhibited by the potent cPLA2 and iPLA2 inhibitor, methyl arachidonyl fluorophosphonate, whereas the iPLA2 inhibitors, R- and S-bromoenol lactone, caused only a partial inhibition. The response was also fully dependent on Ca2+ influx, and the inhibitor studies suggested involvement of the receptor-operated influx pathway. The receptor-operated pathway, on the other hand, was partially dependent on PLA2 activity. The extracellular signal-regulated kinase, but not protein kinase C, were involved in the PLA2 activation at low orexin concentrations.Conclusions and implications: Activation of OX1 orexin receptors induced a strong, high-potency AA release, possibly via multiple PLA2 species, and this response may be important for the receptor-operated Ca2+ influx. The response coincided with other high-potency lipid messenger responses, and may interact with these signals.
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| 41. |
- Turunen, Pauli M., et al.
(author)
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Filtration assay for arachidonic acid release
- 2010
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In: Analytical Biochemistry. - : Elsevier BV. - 0003-2697 .- 1096-0309. ; 407:2, s. 233-236
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Journal article (peer-reviewed)abstract
- Arachidonic acid (AA) release is a central message in cell signaling. Fatty acid release is generally assessed by manual sampling of radioactivity release from cells prelabeled with a radiolabeled fatty acid. The assay is laborious, time-consuming, and susceptible to high noise. Here we present a fast and reproducible method for 96-well filter plates and cells in suspension, a method that is best suited for agonist concentration-response studies and, thus, for ligand screening. The method offers tremendous time and effort savings and enables execution of large experimental series previously unattainable for AA release studies.
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| 42. |
- Åkerman, Karl E. O., et al.
(author)
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Voltage gated calcium channels potentiate muscarinic receptor-mediated calcium responses in SH-SY5Y human neuroblastoma cells
- 1997
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In: Life Sciences. - 0024-3205 .- 1879-0631. ; 60:13-14, s. 1189-
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Journal article (other academic/artistic)abstract
- Muscarinic receptor-mediated Ca2+ elevations were investigated using the fura-2 method and image analysis. Typical responses consisted of an initial fast and transient phase followed by a sustained phase. Removal of external Ca2+ did not affect the magnitude of the initial phase of the signal whereas the sustained phase was abolished. Hence they may mainly consist of a release from intracellular stores and an influx, respectively. Depolarization of the cells with 30 mM KCl in the presence of external Ca2+ caused a small elevation of [Ca2+]i. In these conditions a considerable potentiation of the fast phase of muscarinic Ca2+ response was seen. The potentiation was dependent on the extracellular Ca2+ as it was abolished in the presence of antagonists of voltage-gated Ca2+ channels or by removal of external Ca2+ prior to KCl. Removal of external Ca2+ after the KCl-induced increase in [Ca2+]i partially inhibited the potentiation. If Ca2+ was readded together with the muscarinic stimulation a maximum potentiation was seen. The results suggest that the muscarinic response is potentiated by a Ca2+-mediated priming of both a fast and transient receptor associated Ca2+ influx pathway and release from the intracellular stores.
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