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ABSTRACT: Previously, it was found that total saponins from panax notoginseng inhibited Ca2+ influx coupling to activation of alpha1-adrenoceptor. This study was designed to investigate the effects of ginsenoside-Rd from total saponins of panax notoginseng on receptor-operated (ROCC) and store-operated (SOCC) Ca2+ channels in vascular smooth muscle cells using fura-2 fluorescence, whole cell patch clamp ion channel recording, radio-ligand-receptor binding, 45Ca2+ radio-trace and organ bath techniques. It was found that ginsenoside-Rd reduced phenylephrine-induced contractile responses and Ca2+ influx in normal media without significant effect on these responses in Ca2+ -free media. Ginsenoside-Rd also decreased phenylephrine- and thapsigargin-induced inward Ca2+ currents, and attenuated thapsigargin- and 1-oleoy-2-acetyl-sn-glycerol (OAG)-induced cation entries that are coupled to ROCC and SOCC respectively. Ginsenoside-Rd failed to inhibit KCl-induced contraction of rat aortal rings and Ca2+ influx, and did not alter voltage-dependent inward Ca2+ current (VDCC) which was blocked by nifedipine. Also, ginsenoside-Rd did not change binding site and affinity of [3H]-prazosin for alpha1-adrenoceptor in the vascular plasma membrane. These results suggest that ginsenoside-Rd, as an inhibitor, remarkably inhibits Ca2+ entry through ROCC and SOCC without effects on VDCC and Ca2+ release in vascular smooth muscle cells.
European Journal of Pharmacology 11/2006; 548(1-3):129-36. · 2.52 Impact Factor
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ABSTRACT: To test the hypothesis that Cl channel blockers affect T cell proliferation through Ca2+-release-activated Ca2+ (CRAC) signaling and examine the effects of the combination of a CRAC channel blocker and a Cl channel blocker on concanavalin A (ConA; 5 mg/mL)-induced Ca2+ signaling, gene expression and cellular proliferation in human peripheral T lymphocytes.
[3H]Thymidine incorporation, Fura-2 fluorescent probe, RNase protection assay, and reverse transcription-polymerase chain reaction were used.
The Cl channel blocker 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS) inhibited ConA-induced Ca2+ influx, interleukin-2 mRNA expression and T lymphocyte proliferation in a concentration-dependent manner, and also enhanced the inhibitory effects of 1-[beta-[3-(4-methoxyphenyl)propoxyl]-4-methoxyphenethyl]-1H-imidazole (SK&F96365) on the above key events during T cell activation. A combination of DIDS (1 micromol/L) and SK&F96365 (1 micromol/L) significantly diminished ConA-induced ClC-3 mRNA expression by 64%, whereas DIDS(1 micromol/L) or SK&F96365 (1 micromol/L) alone decreased ConA-induced ClC-3 mRNA expression by only 16% and 9%, respectively.
These results suggest that there is an interaction between CRAC-mediated Ca2+ signaling and DIDS-sensitive Cl channels during ConA-induced T cell activation and proliferation. Moreover, the DIDS-sensitive Cl channels may be related to the ClC-3 Cl channels.
Acta Pharmacologica Sinica 04/2006; 27(4):437-46. · 1.95 Impact Factor
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ABSTRACT: Aim: To test the hypothesis that Cl− channel blockers affect T cell proliferation through Ca2+-release-activated Ca2+ (CRAC) signaling and examine the effects of the combination of a CRAC channel blocker and a Cl− channel blocker on concanavalin A (ConA; 5 mg/mL)-induced Ca2+ signaling, gene expression and cellular proliferation in human peripheral T lymphocytes. Methods: [3H]Thymidine incorporation, Fura-2 fluorescent probe, RNase protection assay, and reverse transcription-polymerase chain reaction were used. Results: The Cl− channel blocker 4,4′-diisothiocyanostilbene-2,2′-disulfonic acid (DIDS) inhibited ConA-induced Ca2+ influx, interleukin-2 mRNA expression and T lymphocyte proliferation in a concentration-dependent manner, and also enhanced the inhibitory effects of 1-{beta-[3-(4-methoxyphenyl)propoxyl]-4-methoxyphenethyl}-1H-imida-zole (SK&F96365) on the above key events during T cell activation. A combination of DIDS (1 μmol/L) and SK&F96365 (1 μmol/L) significantly diminished ConA-induced ClC-3 mRNA expression by 64%, whereasDIDS(1 μmol/L) or SK&F96365 (1 μmol/L) alone decreased ConA-induced ClC-3 mRNA expression by only 16% and 9%, respectively. Conclusion: These results suggest that there is an interaction between CRAC-mediated Ca2+ signaling and DIDS-sensitive Cl channels during ConA-induced T cell activation and proliferation. Moreover, the DIDS-sensitive Cl− channels may be related to the ClC-3 Cl− channels.
Acta Pharmacologica Sinica 03/2006; 27(4):437 - 446. · 1.95 Impact Factor
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ABSTRACT: We previously found that antisense oligonucleotide specific to ClC-3 (ClC-3 antisense) prevented rat aortic smooth muscle cell proliferation, which was related to cell volume regulation. In the present study, we further characterized the regulation of intracellular Cl(-) concentrations ([Cl(-)](i)) via volume-regulated ClC-3 Cl(-) channels in an embryo rat aortic vascular smooth muscle cell line (A10 cell) and ClC-3 cDNA-transfected A10 cells (ClC-3-A10) using multiple approaches including [Cl(-)](i) measurement, whole cell patch clamp, and application of ClC-3 antisense and intracellular dialysis of an anti-ClC-3 antibody. We found that hypotonic solution decreased [Cl(-)](i) and evoked a native I(Cl.vol) in A10 cells. The responses of [Cl(-)](i) and I(Cl.vol) to hypotonic challenge were enhanced by expression of ClC-3, and inhibited by ClC-3 antisense. The currents in A10 (I(Cl.vol)) and in ClC-3-A10 cells (I(Cl.ClC-3)) were remarkably inhibited by intracellular dialysis of anti-ClC-3 antibody. Reduction in [Cl(-)](i) and activation of I(Cl.vol) and I(Cl.ClC-3) in A10 and ClC-3-A10 cells, respectively, were significantly inhibited by activation of protein kinase C (PKC) by phorbol-12,13-dibutyrate (PDBu) and inhibition of tyrosine protein kinase by genistein. Sodium orthovanadate (vanadate), a protein-tyrosine phosphatase inhibitor, however, enhanced the cell swelling-induced reduction in [Cl(-)](i), accompanied by the activation of I(Cl.vol) and I(Cl.ClC-3) in a voltage-independent manner. Our results suggest that the volume-regulated ClC-3 Cl(-) channels play important role in the regulation of [Cl(-)](i) and cell proliferation of vascular smooth muscle cells.
Journal of Biological Chemistry 03/2005; 280(8):7301-8. · 4.77 Impact Factor
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ABSTRACT: Patch-clamp whole-cell recording techniques were used to study ATP-induced Cl- current and the effects of Cl- channel blockers on NO release in bovine aortic endothelial cells. ATP evoked an outward rectified Cl- current with a reversal potential of −29±3 mV. This outward rectified Cl- current was dependent on Ca2+ influx, but not Ca2+ release. In Ca2+-free medium, ATP did not produce the Cl- current; however, subsequent addition of Ca2+ to the medium evoked an ATP-induced outward rectified Cl- current. Furosemide, glibenclamide, and DIDS inhibited ATP-activated Cl- current in a concentration-dependent manner with maximal inhibition of 88±4%, 93±1%, and 79±3%, respectively. The IC50 values of furosemide, glibenclamide, and DIDS were 6.2±2.6, 29.6±12.3, and 21.0±13.4 µM, respectively. These effects of Cl- channel blockers matched those on NO release from endothelial cells. Our data suggest that ATP-induced Ca2+ entry followed by increased [Ca2+]i activates Ca2+-activated Cl- channels which mediate NO release from endothelial cells. Drug Dev. Res. 58:53–56, 2003. © 2003 Wiley-Liss, Inc.
Drug Development Research 02/2003; 58(1):53 - 56. · 1.19 Impact Factor
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ABSTRACT: Recent growing evidence suggests that chloride (Cl-) channels are critical to the cell cycle. In cultured rat aortic vascular smooth muscle cells (VSMCs), we have previously found that Cl- channel blockers inhibit endothelin-1 (ET-1)-induced cell proliferation. The present study was designed to further identify the specific Cl- channels responsible for VSMC proliferation. Due to the lack of a specific blocker or opener of any known Cl- channels, we used the antisense strategy to investigate the potential role of ClC-3, a member of the voltage-gated Cl- channel gene family, in cell proliferation of cultured rat aortic VSMCs. With [3H]-thymidine incorporation and immunoblots, we found that ET-1-induced cell proliferation was parallel to a significant increase in the endogenous expression of ClC-3 protein. Transient transfection of rat aortic VSMCs with antisense oligonucleotide specific to ClC-3 caused an inhibition in ET-1-induced expression of ClC-3 protein and cell proliferation of VSMCs in the same concentration- and time-dependent pattern, whereas sense and missense oligonucleotides resulted in no effects on ClC-3 protein expression and cell proliferation. These results strongly suggest that ClC-3 may be the Cl- channel involved in VSMC proliferation and thus provide compelling molecular evidence linking a specific Cl- channel to cell proliferation. The full text of this article is available at http://www.circresaha.org.
Circulation Research 12/2002; 91(10):E28-32. · 9.49 Impact Factor
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ABSTRACT: The effects of Cl- channel blockers on endothelin-1 (ET-1)-induced proliferation of rat aortic vascular smooth muscle cells (VSMC) were examined. We found ET-1 concentration-dependently increased cell count and [3H]-thymidine incorporation into VSMC, with EC50 values of 24.8 and 11.4 nM, respectively. Both nifedipine and SK&F96365 inhibited 10 nM ET-1-induced [3H]-thymidine incorporation into VSMC with the maximal inhibitory concentrations of 1 and 10 microM, respectively. DIDS inhibited 10 nM ET-1-induced increase in cell count and [3H]-thymidine incorporation into VSMC in a concentration-dependent manner, whereas other Cl- channel blockers including IAA-94, NPPB, DPC, SITS and furosemide did not produce these effects. 3 microM DIDS reduced 10 nM ET-1-induced sustained increase in cytoplasmic Ca2+ concentration ([Ca2+]) by 52%. Pretreatment of VSMC with 1 microM nifedipine completely inhibited the DIDS effect on 10 nM ET-1-induced [3H]-thymidine incorporation into VSMC and sustained increase in [Ca2+]i, whereas pretreatment with 10 microM SK&F96365 did not completely block these effects of DIDS. DIDS did not affect ET-1-induced Ca2+ release and 30 mM KCl-induced increase in [Ca2+]i. Our data suggest that DIDS-sensitive Cl- channels mediate VSMC proliferation induced by ET-1 by mechanisms related to membrane depolarization and Ca2+ influx through voltage-dependent Ca2+ channels.
Life Sciences 04/2002; 70(19):2233-41. · 2.53 Impact Factor
