Abstract:
:In previous studies, we have shown that mouse RAW 264.7 macrophages possess pyrimidinoceptors, coupled to a phosphoinositide-specific phospholipase C, with a higher specificity for UTP than for ATP. In the current study, we explored the mechanism involved in the UTP-induced intracellular acidification seen in this cell line. UTP (30 microM) caused a reversible pHi decrease of 0.16 +/- 0.01 unit; this effect was not influenced by the removal of extracellular Cl- or Na+ ions or by pretreatment with 5-(N-ethyl-N-isopropyl)-amiloride (10 microM), 5-nitro-2-(3-phenylpropylamino)benzoic acid (100 microM), staurosporine (1 microM), or Ro 31-8220 (1 microM) but was completely abolished by the removal of extracellular Ca2+. UTP (30 microM), thapsigargin (1 microM), and ionomycin (1 microM) each induced a similar extent of external Ca2+-dependent acidification with a similar time-dependency, but the effects were nonadditive. To further investigate the Ca2+-dependent mechanism, we studied the involvement of arachidonic acid (AA) and eicosanoid metabolites. The addition of AA (10 microM) but not arachidic acid (100 microM) produced a reduction in pHi. UTP, thapsigargin, and ionomycin induced Ca2+-dependent AA release. Furthermore, 4-bromo-phenacyl bromide [30 microM, a phospholipase A2 (PLA2) inhibitor-, nordihydroguaiaretic acid (50 microM, a lipoxygenase inhibitor), and MK-886 (10 microM, a 5-lipoxygenase-activating protein inhibitor) abolished the UTP- or ionomycin-induced responses, whereas indomethacin (30 microM, a cyclooxygenase inhibitor) and baicalein (10 microM, a selective 12-lipoxygenase inhibitor) had no effect. MAFP (a cPLA2 inhibitor) and REV 5901 (a 5-lipoxygenase inhibitor as well as a competitive antagonist of peptide leukotrienes), but not RHC 80267 (a diacylglycerol lipase inhibitor), also inhibited the UTP-induced response. In contrast, the pHi response to AA was unaffected by the presence of 4-bromo-phenacyl bromide or the removal of extracellular Ca2+ ions but abolished by addition of NDGA. Exogenous 5-hydroperoxyeicosatetraenoic acid (2 microM) also produced marked acidification, and UTP and ionomycin both induced peptide leukotriene formation. In conclusion, this is the first report indicating that lipoxygenase metabolites act as mediators of the Ca2+-dependent acidification seen in macrophages in response to UTP or ionomycin via activation of cPLA2 and AA release.
journal_name
Mol Pharmacoljournal_title
Molecular pharmacologyauthors
Lin WW,Chang SH,Wu MLdoi
10.1124/mol.53.2.313subject
Has Abstractpub_date
1998-02-01 00:00:00pages
313-21issue
2eissn
0026-895Xissn
1521-0111journal_volume
53pub_type
杂志文章abstract::Extracellular protons inhibit N-methyl-D-aspartate (NMDA) receptors with an IC50 value in the physiological pH range. To identify the molecular determinants of proton sensitivity, we used scanning mutagenesis of the NR1 subunit to search for residues that control proton inhibition of NMDA receptors. Homology modeling ...
journal_title:Molecular pharmacology
pub_type: 杂志文章
doi:10.1124/mol.63.6.1212
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abstract::The effects of single and repeated electroconvulsive shock (ECS) on the binding of [3H]diprenorphine to rat brain membranes was studied. Repeated but not single ECS significantly increased the Bmax of [3H]diprenorphine binding when measured in the absence but not in the presence of NaCl. On a regional basis the effect...
journal_title:Molecular pharmacology
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journal_title:Molecular pharmacology
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更新日期:1985-04-01 00:00:00
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journal_title:Molecular pharmacology
pub_type: 杂志文章
doi:
更新日期:1986-04-01 00:00:00
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journal_title:Molecular pharmacology
pub_type: 杂志文章
doi:10.1124/mol.113.089482
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journal_title:Molecular pharmacology
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doi:
更新日期:1988-09-01 00:00:00
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pub_type: 评论,杂志文章
doi:10.1124/mol.105.011429
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journal_title:Molecular pharmacology
pub_type: 杂志文章
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journal_title:Molecular pharmacology
pub_type: 杂志文章
doi:10.1124/mol.56.6.1229
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doi:
更新日期:1996-03-01 00:00:00
abstract::Inhibition of cathepsin C, a dipeptidyl peptidase that activates many serine proteases, represents an attractive therapeutic strategy for inflammatory diseases with a high neutrophil burden. We recently showed the feasibility of blocking the activation of neutrophil elastase, cathepsin G, and proteinase-3 with a singl...
journal_title:Molecular pharmacology
pub_type: 杂志文章
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journal_title:Molecular pharmacology
pub_type: 杂志文章
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journal_title:Molecular pharmacology
pub_type: 杂志文章
doi:
更新日期:1992-05-01 00:00:00
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pub_type: 杂志文章,评审
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journal_title:Molecular pharmacology
pub_type: 杂志文章
doi:
更新日期:1991-11-01 00:00:00
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journal_title:Molecular pharmacology
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journal_title:Molecular pharmacology
pub_type: 杂志文章
doi:
更新日期:1989-03-01 00:00:00
abstract::Melanoma differentiation associated gene-7 (mda-7)/interleukin-24 (IL-24), a member of the IL-10 cytokine gene family, preferentially induces cell death in neoplastic epithelial cells types while sparing their normal counterparts. The effects of mda-7/IL-24 in acute myeloid leukemia (AML) cells have not been extensive...
journal_title:Molecular pharmacology
pub_type: 杂志文章
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journal_title:Molecular pharmacology
pub_type: 杂志文章
doi:
更新日期:1989-01-01 00:00:00
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journal_title:Molecular pharmacology
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journal_title:Molecular pharmacology
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