Cordycepin Attenuates Neointimal Formation by Inhibiting Reactive Oxygen Species–Mediated Responses in Vascular Smooth Muscle Cells in Rats

We determined the action mechanism of cordycepin, a major bioactive component of Cordyceps militaris, on responses of rat aortic smooth muscle cells (RASMCs) and on vascular disorders, especially neointimal formation. Cordycepin inhibited platelet-derived growth factor-BB (PDGF-BB)-induced RASMCs migration and proliferation in a dose-dependent manner. However, pre-treatment with N^ω-nitro-L-arginine methyl ester, a nitric oxide synthase (NOS) inhibitor, and 1,3-dipropyl-8-sulphophenylxanthine (DPSPX), an A₁/A₂ adenosine– receptor antagonist, abolished the inhibitory role of cordycepin. Cordycepin suppressed the phosphorylation of p38 mitogen–activated protein kinase (p38 MAPK) and heat shock protein 27 (Hsp27), but not that of extracellular signal-regulated kinase (ERK) 1/2 in RASMCs stimulated by PDGF-BB. The production of reactive oxygen species (ROS), O₂^? and H₂O₂, induced by PDGF-BB was abolished by the treatment of cordycepin. Moreover, the sprout outgrowth of aortic rings by PDGF-BB was inhibited by cordycepin. In vivo neointimal formation evoked by balloon-injury was significantly attenuated by the administration of cordycepin. These results demonstrate that cordycepin may exert inhibitory effects on PDGF-BB–induced migration and proliferation via interfering with adenosine receptor–mediated NOS pathways, thus resulting in the attenuation of neointima formation. In conclusion, cordycepin may be a potent, promising anti-atherosclerosis agent.     

Olibanum Extract Inhibits Vascular Smooth Muscle Cell Migration and Proliferation in Response to Platelet-Derived Growth Factor

Olibanum (Boswellia serrata) has been shown to have anti-inflammatory, anti-arthritic and anti-cancer effects. This study determined the role of a water extract of olibanum in platelet-derived growth factor (PDGF)-stimulated proliferation and migration of rat aortic smooth muscle cells (RASMCs). PDGF-BB induced the migration and proliferation of RASMCs that were inhibited by olibanum extract in a dose-dependent manner. The PDGF-BB-increased phosphorylation of p38 mitogen-activated protein kinase (MAPK); the heat shock protein (Hsp) 27 was significantly inhibited by the olibanum extract. The effects of PDGF-BB-induced extracellular signal-regulated kinase1/2 was not altered by the olibanum extract. Treatment with olibanum extract inhibited PDGF-BB-stimulated sprout out growth of aortic rings. These results suggest that the water extract of olibanum inhibits PDGF-BB-stimulated migration and proliferation in RASMCs as well as sprout out growth, which may be mediated by the inhibition of the p38 MAPK and Hsp27 pathways.     

Spleen tyrosine kinase participates in src-mediated migration and proliferation by PDGF-BB in rat aortic smooth muscle cells

Tyrosine kinases, Src and spleen tyrosine kinase (Syk), play crucial roles in cell responses to platelet-derived growth factor (PDGF) and may have their functional interactions. In this study, we focused on investigating the roles of Syk in the regulation of Src signaling in PDGF-mediated vascular cell responses. Migration, proliferation, and activity of kinases were determined in rat aortic smooth muscle cells (RASMCs). PDGF-BB (10 ng/mL) induced the migration and proliferation of RASMCs, which were significantly inhibited by PP2 (10 microM) and piceatannol (30 microM), inhibitors of Src and Syk, respectively. The phosphorylation of Syk induced by PDGF-BB was abolished by PP2. PDGF-BB increased the co-association of the PDGFbeta-receptor and the kinases, Src or Syk, and its maximal binding to Src was achieved in a shorter time than that to Syk. PDGF-BB stimulated the phosphorylation of p38 mitogen-activated protein kinase (MAPK) and extracellular signal-regulated kinase (ERK) 1/2, which was inhibited by PP2 and piceatannol. PDGF-BB-induced proliferation and migration were inhibited by SB203580 (30 microM) and PD98059 (30 microM), inhibitors of p38 MAPK and ERK1/2, respectively. These results imply that Syk is regulated by Src kinase, which participates in migration and proliferation in response to PDGF-BB in RASMCs.     

DEVELOPMENTALLY REGULATED TRANSFORMING GROWTH FACTOR-β1 ACTION ON VASCULAR SMOOTH MUSCLE GROWTH IN THE SHR

1. This study examined the effects of transforming growth factor-β11 (TGF-β1) on platelet-derived growth factor-BB (PDGF-BB)-stimulated proliferation of vascular smooth muscle cells (VSMC) isolated from aortic tissue of I, 4 and 12 week old spontaneously hypertensive rats (SHR). 2. In 1 week old SHR, TGF-βl inhibited by about 60% VSMC proliferation stimulated by PDGF-BB; this inhibitory action of TGF-β1 was absent in VSMC isolated from 4 week old, prehypertensive SHR. In contrast, TGF-β1 potentiated by about 125% the mitogenic activity of PDGF-BB in VSMC cultures from adult SHR. 3. Age-dependent alterations in the action of TGF-β1 suggests an important role for TGF-β1 in the development of vascular hypertrophy from adolescence onwards in the SHR.     

Dominant negative c-Jun inhibits platelet-derived growth factor-directed migration by vascular smooth muscle cells

The mitogen-activated protein (MAP) kinase pathways has been shown to be necessary for mitogen-stimulated proliferation, but its role in cell migration has not been fully understood. In this study, we investigated the possible contribution of signaling pathways through c-Jun in platelet-derived growth factor (PDGF)-BB directed cell migration in rat aortic vascular smooth muscle cells (VSMCs) infected with a recombinant adenovirus containing the dominant-negative c-Jun (Ad-DN-c-Jun). DN-c-Jun protein was expressed dose-dependently in VSMCs infected with Ad-DN-c-Jun. Expression of DN-c-Jun significantly inhibited VSMC migration induced by PDGF-BB. Our results provide the first evidence that signaling pathways through c-Jun participates in cell migration induced by PDGF-BB in addition to other MAP kinase pathways in VSMCs.     

Increased phosphodiesterase 3A/4B expression after angioplasty and the effect on VASP phosphorylation

The beneficial effects of coronary angioplasty are limited by the proliferation and migration of vascular smooth muscle cells leading to restenosis. We hypothesized that increased activity of phosphodiesterase (PDE) after angioplasty in response to growth factors such as platelet-derived growth factor (PDGF)-BB and fibroblast growth factor (FGF), leads to reduced cAMP levels, which, in turn, may contribute to vascular smooth muscle cell proliferation. In rats subjected to angioplasty, aortic expression and activity of PDE3/PDE4 were increased within 24 h and associated with reduced phosphorylation of vasodilator-stimulated phosphoprotein (VASP), a substrate for cAMP-dependent protein kinase A (PKA). Inhibition of PDE3 increased VASP phosphorylation in aortic rings from rats subjected to angioplasty, whereas inhibition of PDE4 or stimulation of adenylate cyclase with isoproterenol was without effect; however, combined inhibition of PDE3 and PDE4 produced a synergistic effect on VASP phosphorylation. In cultured vascular smooth muscle cells, exposure to PDGF-BB resulted in increased expression of PDE3, which was prevented by an inhibitor of PI3 kinase but not by inhibitors of the MAP kinase signaling pathway. In contrast, FGF increased the expression of PDE4 in vascular smooth muscle cells but did not influence expression of PDE3. This study shows that angioplasty results in increased expression/activity of PDE, possibly arising from stimulation by PDGF-BB and FGF, and decreased cAMP levels, which may promote restenosis. These results provide a rational explanation for the beneficial effects of PDE inhibitors.     

人参炔醇对大鼠主动脉平滑肌细胞增殖的抑制作用及机制

目的观察人参炔醇(panaxynol,PNN)对大鼠主动脉平滑肌细胞(RASMC)增殖的抑制作用及机制。方法由细胞计数、[3H]TdR参入试验确定细胞增殖率,采用分子探针Fura-3/AM及共聚焦显微镜检测胞内游离Ca2+浓度([Ca2+]i),RT-PCR方法观察线粒体转录因子1(m tTF1)mRNA的表达。结果PNN以浓度依赖方式抑制血清及PDGF-BB诱导的RASMC增殖和DNA合成;9μmol.L-1PNN预处理RASMC能抑制PDGF-BB引起的[Ca2+]i升高;PDGF-BB上调RASMC m tTF1 mRNA表达,该作用可被3、9μmol.L-1的PNN抑制。结论PNN具有抗RASMC增殖作用,该作用与降低[Ca2+]i和抑制m tTF1 mRNA表达有关。     

Platonin inhibited PDGF-BB-induced proliferation of rat vascular smooth muscle cells via JNK1/2-dependent signaling

Aim:

To examine the inhibitory actions of the immunoregulator platonin against proliferation of rat vascular smooth muscle cells (VSMCs).

Methods:

VSMCs were prepared from the thoracic aortas of male Wistar rats. Cell proliferation was examined using MTT assays. Cell cycles were analyzed using flow cytometry. c-Jun N-terminal kinase (JNK)1/2, extracellular signal-regulated kinase (ERK)1/2, AKT, and c-Jun phosphorylation or p27 expression were detected using immunoblotting.

Results:

Pretreatment with platonin (1–5 μmol/L) significantly suppressed VSMC proliferation stimulated by PDGF-BB (10 ng/mL) or 10% fetal bovine serum (FBS), and arrested cell cycle progression in the S and G₂/M phases. The same concentrations of platonin significantly inhibited the phosphorylation of JNK1/2 but not ERK1/2 or AKT in VSMCs stimulated by PDGF-BB. Furthermore, platonin also attenuated c-Jun phosphorylation and markedly reversed the down-regulation of p27 expression after PDGF-BB stimulation.

Conclusion:

Platonin inhibited VSMC proliferation, possibly via inhibiting phosphorylation of JNK1/2 and c-Jun, and reversal of p27 down-regulation, thereby leading to cell cycle arrest at the S and G₂/M phases. Thus, platonin may represent a novel approach for lowering the risk of abnormal VSMC proliferation and related vascular diseases.     

p38 mitogen-activated protein kinase contributes to angiotensin II-stimulated migration of rat aortic smooth muscle cells

In this study, we clarified the intracellular mechanism of angiotensin II (Ang II) in promoting migration in rat aortic smooth muscle cells (RASMCs). RASMC migration was measured with the Boyden chamber assay, and the result was confirmed with an aortic sprout assay. The activities of kinases were investigated by western blot analysis. Ang II enhanced RASMC migration, which was chemotaxis directed, and induced the phosphorylation of p38 mitogen-activated protein kinase (MAPK), extracellular signal-regulated kinase 1/2 (ERK1/2), and heat shock protein 27 (Hsp27). Ang II-enhanced cell migration was inhibited by SB203580 (a p38 MAPK inhibitor) and piceatannol (a spleen tyrosine kinase inhibitor), but only partially by PD98059 (an ERK inhibitor) and PP2 (a Src inhibitor). The Ang II-stimulated phosphorylation of p38 MAPK and Hsp27 in RASMCs was inhibited by piceatannol and SB203580. The phosphorylation of ERK1/2 stimulated by Ang II was suppressed by PD98059, piceatannol, and PP2. Ang II increased the sprout outgrowth from aortic rings and this response was attenuated by pretreatment with SB203580, PD98059, PP2, or piceatannol. These results suggest that p38 MAPK contributes to the regulation of the Ang II-induced chemotactic migration of vascular smooth muscle cells, which is mediated by Hsp27 phosphorylation.     

The effect of 2,3,4′,5-tetrahydroxystilbene-2-0-β-d glucoside on neointima formation in a rat artery balloon injury model and its possible mechanisms

2,3,4′,5-tetrahydroxystilbene-2-0-β-d glucoside (TSG) has been recognized to suppress the proliferation of vascular smooth muscle cells (VSMCs). The aim of the present study was to determine whether TSG inhibits neointimal hyperplasia in a rat carotid arterial balloon injury model. Balloon injury was induced in the left common carotid artery of rats. TSG (30, 60, 120 mg/kg/day) was treated from 3 days prior to, until 14 days after the induction of balloon injury. The ratio of intima-to-media was significantly reduced in the TSG-treated rats at 14 days after the induction of injury, which was associated with reduced expressions of proliferating cell nuclear antigen (PCNA), α-smooth muscle actin (α-SMA) and platelet-derived growth factor-BB (PDGF-BB), as markers of VSMCs proliferation and migration. Additionally, TSG significantly inhibited PDGF-BB induced cell migration in cultured VSMCs. Furthermore, we explored the underlying mechanisms for such effects of TSG. The result showed that TSG markedly reduced balloon injury-induced AKT, extracellular signal-regulated kinase (ERK1/2) and nuclear factor kappaB (NF-κB) activation as well as mRNA expressions of c-myc, c-fos and c-jun, which is important signal pathway for VSMCs proliferation. And in both vivo and vitro model, TSG markedly regulated matrix metalloproteinase-2, 9 expressions and collagen I, III expressions, which are key factors in extracellular matrix for VSMCs migration. These results suggest that the anti-proliferative and anti-migrative effects of TSG on VSMCs could help to explain the beneficial effects of TSG on neointima hyperplasia induced by balloon injury.     

Nicotinic acetylcholine receptor α7 inhibits platelet-derived growth factor-induced migration of vascular smooth muscle cells by activating mitochondrial deacetylase SIRT3

OBJECTIVE Platelet-derived growth factorBB(PDGF-BB) is an angiogenic factor involved in cardiovascular diseases. Here, we investigated the possible effects of activation of nicotinic acetylcholine receptor α7 subtype(α7nAChR) on PDGF-BB-induced proliferation and migration in vascular smooth muscle cells(VSMCs).METHODS We were determined using transwell migra-tion assay and scratch-wound migration assay. To determine VSMCS migration. Cell viability was measured using CCK-8 assay. Cell proliferation was measured by Click-iTEdU Microplate Assay. Mitochondria were isolated using a commercial kit from Biovision. Intracellular reactive oxygen species(ROS) was determined by DCFH-DA probe. We used by SDS-PAGE to determined some proteins.NAD+levels were determined with acommercial NAD+quantification kit. Citrate synthase(CS) activity was measured by colorimetric assay kits. RESULTS PDGF-BB induced pronounced migration and proliferation in VSMCs. Activation ofα7nAChR by PNU-282987 blocked the PDGF-BBinduced VSMCs migration but not proliferation in WT VSMCs, whereas this effect was absent in α7nAChRknockout VSMCs. Accordingly, PNU-282987 attenuated PDGF-BB-induced phosphorylation of FAKTyr397 and Src Tyr416 in WT VSMCs. Mechanistically, PNU-282987 suppressed the PDGF-BB-induced oxidative stress,evidenced by the alterations in reactive oxygen species,H_2O_2 content, superoxide anion and total anti-oxidant activity. A SIRT3 inhibitor 3-(1 H-1, 2, 3-triazol-4-yl) pyridine or sh RNA-mediated SIRT3 knockdown abolished the inhibitory effect of PNU-282987. PNU-282987 treatment did not modulate SIRT3 protein expression, but enhanced mitochondrial SIRT3 deacetylase activity. In line with this action, PNU-282987 enhanced the deacetylation of mitochondrial FoxO3. At last, PNU-282987 treatment corrected PDGF-BB-induced mitochondrial dysfunction by increasing mitochondrial citrate synthase activity,ATP content and nicotinamide adenine dinucleotide pool.CONCLUSION Pharmacological y activation of α7nAChR inhibits PDGF-BB-induced VSMC migration via activating mitochondrial deacetylase SIRT3, implying an important role of α7nAChR in mitochondria biology and PDGF-related diseases.     

Cepharanthine inhibits in vitro VSMC proliferation and migration and vascular inflammatory responses mediated by RAW264.7

Pathogenesis of atherosclerosis involves vascular smooth muscle cell (VSMC) migration and proliferation followed by an inflammation mediated by activated macrophages in the tunica intima of blood vessels. Cepharanthine (CEP) belongs to bisbenzylisoquinoline alkaloids found in the plant Stephania cepharantha, which has been used for various diseases like cancer, alopecia areata, venomous snakebites, and malaria. In this study, we investigated whether CEP suppresses VSMC migration and proliferation and inhibits inflammatory mediator production in macrophage (RAW264.7). Our results showed that CEP possessed significant DPPH scavenging and metal chelating activities. It also markedly inhibited lipid peroxidation. Similarly, CEP suppressed the nitric oxide (NO) production and expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX-2) in RAW264.7 cells. Moreover, the level of prostaglandin E₂ was also suppressed and the formation of macrophage derived foam cell was attenuated in RAW264.7 cells. Likewise, NO production in isolated peritoneal macrophage and VSMC migration in response to LPS stimulated RAW264.7 was also halted by CEP treatment. Also, VSMC migration induced by platelet-derived growth factor (PDGF-BB) was inhibited by CEP dose dependently. The anti-migratory effect of CEP on VSMCs was due to its inhibitory effect on metalloproteinase-9 (MMP-9) expression, preventing the degradation of extracellular matrix (ECM) component. Furthermore, CEP suppressed PDGF-BB induced VSMC proliferation by down-regulation of mitogen activated protein kinase (MAPK) signaling molecules. CEP also inhibited the translocation of NF-κB from cytosol to nucleus. Thus, our results suggest that CEP exerts potent anti-atherosclerotic effect through attenuation of inflammation, lipid peroxidation and VSMC migration and proliferation.     

Luteolin prevents PDGF-BB-induced proliferation of vascular smooth muscle cells by inhibition of PDGF beta-receptor phosphorylation

Luteolin occurs as glycosylated forms in celery, green pepper, perilla leaf and camomile tea, and has been shown to possess antimutagenic, antitumorigenic, antioxidant and antiinflammatory properties. In this study, we have investigated the antiproliferable effect and its mechanism of luteolin on platelet-derived growth factor (PDGF)-BB-induced proliferation of rat aortic vascular smooth muscle cells (VSMCs). Luteolin significantly inhibited PDGF-BB-induced proliferation and DNA synthesis of rat aortic VSMCs in a concentration-dependent manner. In addition, flow cytometry analysis of DNA content revealed blocking of the PDGF-BB-inducible cell cycle progression by luteolin. Pre-incubation of rat aortic VSMCs with luteolin significantly inhibited the PDGF-BB-induced extracellular signal-regulated kinase 1/2 (ERK1/2), Akt and phospholipase C (PLC)-gamma1 activation as well as c-fos gene expression. Consisted with these findings, luteolin inhibited PDGF-Rbeta phosphorylation induced by PDGF-BB in a concentration-dependent manner. These results suggest that the inhibitory effect of luteolin on the PDGF-BB-induced proliferation of rat aortic VSMCs may be mediated by blocking phosphorylation of PDGF-Rbeta.     

Inhibition of human pulmonary artery smooth muscle cell proliferation and migration by sabiporide, a new specific NHE-1 inhibitor

Abnormal growth of vascular smooth muscle cells is seen in various pathological conditions such as hypertension, atherosclerosis, and restenosis. Na/H exchanger (NHE) activation appears to play a permissive role in vascular smooth muscle cell proliferation and vascular remodeling. The present study investigated the effect of a new specific NHE-1 inhibitor, sabiporide, on human pulmonary artery smooth muscle cell proliferation and migration. Concentrations of sabiporide as low as 20 micromol/L in the culture medium containing growth factors inhibited cell proliferation, as measured by cell counting, and also inhibited the rate of DNA synthesis, as examined by measuring BrdU incorporation into DNA. Cell growth inhibition was not caused by cell death, as demonstrated by the measurement of intracellular lactate dehydrogenase release and by the reversibility of inhibition upon washing. By fluorescent-activated cell sorting analysis, we are the first to demonstrate that NHE-1 inhibition arrests the cell cycle progression at G0/G1 phase, suggesting that NHE activation plays a permissive role in entrance of cells into the cell cycle. Sabiporide also concentration-dependently inhibited human pulmonary artery smooth muscle cell migration. The present study showed that sabiporide inhibits vascular smooth muscle cell proliferation and migration by blocking the cell cycle progression at G0/G1 phase.     

Effect of calcitonin gene-related peptide on angiotensin II-induced proliferation of rat vascular smooth muscle cells

The present study was designed to examine the effect of calcitonin gene-related peptide (CGRP) on angiotensin II-induced proliferation of cultured rat vascular smooth muscle cells. Vascular smooth muscle cells were grown from explants of Sprague-Dawley rat aorta. Vascular smooth muscle cells (between passages 5 and 10) were incubated with 0.1% neonatal calf serum for 48 h, and then treated with angiotensin II (100 nM) in the absence or presence of CGRP for 24 h. The viability, DNA synthesis and cell cycle of vascular smooth muscle cells were measured. Western blotting was used to determine the activity of intracellular extracellular regulated kinase (ERK1/2). Angiotensin II significantly decreased the viability and proliferation of vascular smooth muscle cells, decreased the proliferation index, and increased the activity of ERK1/2; the effects of angiotensin II were inhibited by CGRP (1-100 nM) in a concentration-dependent manner. In conclusion, CGRP significantly inhibits angiotensin II-induced proliferation of vascular smooth muscle cells, an effect related to a decrease in the activation of mitogen-activated protein kinase pathway.     

Effects of apigenin on the serum- and platelet derived growth factor-BB-induced proliferation of rat aortic vascular smooth muscle cells

The inhibitory effects of apigenin on the growth factor-induced proliferative responses, and expression of mitogen-activated protein (MAP) kinase and its downstream c-fos in rat aortic vascular smooth muscle cells (VSMCs) were investigated. Apigenin significantly inhibited both 5 % fetal bovine serum (FBS)- and 50 ng/mL platelet derived growth factor-BB (PDGF-BB)-induced proliferation on primary cultured rat VSMCs in a concentration-dependent manner. In addition, apigenin resulted in a significant inhibition of the FBS-induced phosphorylation of extracellular signal-regulated kinase 1/2 (ERK 1/2) and expression of c-fos mRNA. These results suggest that apigenin inhibits FBS- and PDGF-BB-induced VSMC proliferation, and its activity may be mediated, at least in part, by down regulation of ERK 1/2 and its downstream c-fos mRNA.     

Serotonin induces pulmonary artery smooth muscle cell migration

The chronic phase of pulmonary arterial hypertension (PAH) is associated with vascular remodeling, especially thickening of the smooth muscle layer of large pulmonary arteries and muscularization of small pulmonary vessels, which normally have no associated smooth muscle. Serotonin (5-hydroxytryptamine, 5-HT) has been shown to induce proliferation and hypertrophy of pulmonary artery smooth muscle cells (PASMC), and may be important for in vivo pulmonary vascular remodeling. Here, we show that 5-HT stimulates migration of pulmonary artery PASMC. Treatment with 5-HT for 16h increased migration of PASMC up to four-fold as monitored in a modified Boyden chamber assay. Increased migratory responses were associated with cellular morphological changes and reorganization of the actin cytoskeleton. 5-HT-induced alterations in morphology were previously shown in our laboratory to require cAMP [Lee SL, Fanburg BL. Serotonin produces a configurational change of cultured smooth muscle cells that is associated with elevation of intracellular cAMP. J Cell Phys 1992;150(2):396-405], and the 5-HT4 receptor was pharmacologically determined to be the primary activator of cAMP in bovine PASMC [Becker BN, Gettys TW, Middleton JP, Olsen CL, Albers FJ, Lee SL, et al. 8-Hydroxy-2-(di-n-propylamino)tetralin-responsive 5-hydroxytryptamine4-like receptor expressed in bovine pulmonary artery smooth muscle cells. Mol Pharmacol 1992;42(5):817-25]. We examined the role of the 5-HT4 receptor and cAMP in 5-HT-induced bovine PASMC migration. PASMC express 5-HT4 receptor mRNA, and a 5-HT4 receptor antagonist and a cAMP antagonist completely blocked 5-HT-induced cellular migration. Consistent with our previous report that a cAMP-dependent Cl(-) channel is required for 5-HT-induced morphological changes in PASMC, phenylanthranilic acid, a Cl(-) channel blocker, inhibited actin cytoskeletal reorganization and migration produced by 5-HT. We conclude that 5-HT stimulates PASMC migration and associated cytoskeletal reorganization through the 5-HT4 receptor and cAMP activation of a chloride channel.     

Pharmacological characterisation of the beta-adrenoceptor expressed by human lung mast cells

This study investigated whether human vascular smooth muscle cell proliferation induced by native low-density lipoprotein (LDL) is affected by green tea catechins. Furthermore, the effects of native LDL on extracellular signal-regulated kinase (ERK) 1/2 activity were determined. Cell proliferation stimulated by native LDL was concentration-dependently inhibited by epigallocatechin, epigallocatechin-3-gallate, green tea polyphenon, and the nonspecific antioxidant N-acetylcysteine (P<0.05). Combined treatment of green tea polyphenon and N-acetylcysteine markedly potentiated the effect of each drug on vascular smooth muscle cell proliferation. ERK1/2 activity was only partly inhibited by green tea catechins alone or in combination with N-acetylcysteine (P<0.05). These data suggest that green tea constituents inhibit proliferation of human vascular smooth muscle cells exposed to high levels of native LDL. Green tea constituents and antioxidants may exert vascular protection by inhibiting human vascular smooth muscle cell growth associated with hypercholesterolemia.     

The involvement of reactive oxygen species and arachidonic acid in α1-adrenoceptor-induced smooth muscle cell proliferation and migration

1. In a previous study, we demonstrated phenylephrine-stimulated arachidonic acid (AA) release in rabbit cultured aortic smooth muscle cells. Therefore, we have investigated the functional implications of AA which are involved in the cellular response to phenylephrine, particularly proliferation and migration of rabbit cultured aortic smooth muscle cells.
2. First, to determine whether AA directly modifies proliferation and mobility of vascular smooth muscle cells (VSMCs), we exposed the cells to AA. AA induced proliferation and migration of the cells in a dose-dependent fashion. Concomitantly added catalase inhibited the proliferation and chemotaxis induced by AA of VSMCs. Conversely, aminotriazole enhanced the proliferation and migration induced by AA.
3. Secondly, we investigated whether the proliferation and migration of VSMCs by phenylephrine were related to AA and hydrogen peroxide (H₂O₂). The proliferation and chemotaxis of VSMCs by phenylephrine were inhibited by a phospholipase A₂ (PLA₂) inhibitor, or catalase.
4. Lastly, we investigated the effects of AA and phenylephrine on the content of H₂O₂ in VSMCs. AA and phenylephrine treatment led to an increase of H₂O₂ in a dose-dependent manner.
5. These results suggest that the addition of phenylephrine to the cells caused the enhancement of proliferation and migration, probably by mediating AA release and reactive oxygen species (ROS) production.