Urocortin, the neuropeptide, inhibits the viability of ECV304 cells and rat vascular smooth muscle cells

Objective: This study aims to investigate the effects of urocortin (Ucn) on the viability of endothelial cells (ECV304) and rat vascular muscle cells (VSMC). Methods: Rat aortic VSMC were isolated from the rats' thoracic aorta. We studied the effect of Ucn on the viability of ECV304 cells and VSMC by using a tetrazolium (MTT) assay.Results: Ucn (10 -7 mol/L) inhibited the viability of ECV304 cells and VSMC. Inhibition rates are 13% and 15%, respectively(P<0.05, compared with Control). This inhibition was not dependent on the affecting time and was not affected by the addition of ATP-sensitive potassium channel (KATP channel) blocker, glybenclamide (Gly, 10 mol/L). Conclusion: Ucn inhibits the viability of ECV304 and VSMC. Our results suggest that Ucn may be a new vasoactive agent and may have a beneficial effect in the process of vascular remodeling (VR).

Arsenic trioxide inhibites transgenic tumor necrosis factor-α promoter activity in vascular smooth muscle cells and THP-1 monocytes in vitro

Aim This study was to evaluate the effect of arsenic trioxide （As2O3） on the transgenic TNF-α promoter activity in cultured vascular smooth muscle cells （VSMCs） and THP-1 monocytes. Methods Human TNF-α promoter was constructed by reporter gene system and was transiently transfected into VSMCs and THP-1 in vitro. The promoter activity was tested by luciferase activity with or without LPS and Ang Ⅱ stimulation, before and after different dosage of As2O3 treatment. Results 1. TNF-α promoter effectively expressed in VSMCs and THP-1 compared with CMV promoter （58.3% and 80.9%, respectively）. Both LPS and Ang Ⅱ significantly up-regulated TNF-α promoter activity （P〈0.05）. 2. As2O3 significantly inhibited, both intact and LPS/Ang Ⅱ stimulated promoter activity, in a dose dependent manner （P〈0.05）, and in both cell type. Conclusion These results manifested that, the inhibition effect of As2O3 on the activity of human TNF-α promoter indicated its potential inhibition on pro-inflammatory cytokine genes expression at transcriptional level and its potential anti-inflammatory property in the cardiovascular system.

Effect of Intravascular Irradiation on Intimal Smooth Muscle Cells Proliferation and Apoptosis in Balloon Injuried Arteries

Objective: To investigate the effect of intravascular in radiation on thearterial wall smooth muscle cells (SMCs) proliferation and apoptosis after iliac artery bollominjury in figs. Methods: Twenty-seven miniature figs were divided into three groups. All pigsunderwent iliac artery balloon over-stretch. An^(192) Ir source through afterloader was positionedat the injuried segments to give 10 Gy in 9 pigs and 20 Gy in the other 9 pigs, and the rest 9 pigswere, used as control group. The pigs were killed on the 3rd, 10th and 28th days respectively forobservation. The injured segments were processed to examine SMCs proliferation by proliferation cellnuclear antigen (PCNA) and apopto-sis by terminal deoxynucleotidyl transferase-mediated dUTPnick-end labeling (TUNEL). Results: PC-NA index analysis has some that SMCs proliferation inneointima was significantly inhibited in irradiation group on the 10th and 28th days. The value forintimal SMCs apoptosis in control vs 10 Gy and 20 Gy irradiation groups were: (1. 185+-0. 49)% vs(2. 27+-0. 49)%(P>0. 05) and (1. 85+-0. 49)% vs (2. 53+-0. 45)%(P<0. 05), at the 10th day; (1.61+-0. 35)% vs (3. 11+-0. 51)%(P<0. 05), and (1.61+-0. 35)% vs (7. 05+-1. 82)% (P<0. 05), on the28th day. In irradiated arteries, the maximal incidence of intimal SMCs apoptosis was (7. 05+--1.82)% in 20 Gy group vs (3. 11+-0. 51)% in 10 Gy group (P<0. 05), on the 28th day. In the same doseirradiation group, the incidence of intimal SMCs apoptosis was higher on the 28th day than that onthe 10th day. Conclusion: Intra-arterial gamma irradiation can inhibit intimal SMCs proliferationand stimulate SMCs apoptosis in balloon-in jured arteries. These may be contributive to preventionof restenosis of arteries after balloon injury.

Effects of Tetrandrine on Cytosolic Free Calcium in Cultured Bovine Aortic Smooth Muscle Cells

\ The effects of tetrandrine (Tet) on cytosolic free calcium ([Ca2+]i) in subcultured bovine aortic smooth muscle cells (SMC) were studied by Fura2 and ARCMMIC cation measurement system. Tet (1～100 μmol·L-1) had no effect on the resting [Ca2+]i, but had inhibitory effects on [Ca2+]i elevation induced by high K+, 5HT, ATP, Ang II and NE in the presence of extracellular Ca2+. High concentration of Tet also inhibited Pheinduced [Ca2+]i elevation in absence of extracellular Ca2+. Tet (1～100 μmol·L-1) inhibited KCl (60 mmol·L-1) induced [Ca2+]i elevation in dosedependent manner, the IC50 value was 9.2 (95% confidence limits: 5.7～14.9) mmol·L-1. The results suggested that Tet had blocking effects on both VOC and ROC in bovine aortic SMC. It appears that the mechanisms of blocking effect of Tet on ROC might be primarily due to its Ca2+ entry blocking effects.

Baicalin inhibits PDGF-BB-stimulated vascular smooth muscle cell proliferation through suppressing PDGFRβ-ERK signaling and increase in p27 accumulation and prevents injury-induced neointimal hyperplasia

The increased proliferation and migration of vascular smooth muscle cells （VSMCs） are key events in the development of atherosclerotic lesions. Baicalin, an herb-derived flavonoid compound, has been previously shown to induce apoptosis and growth inhibition in cancer cells through multiple pathways. However, the potential role of baicalin in regulation of VSMC proliferation and prevention of cardiovascular diseases remains unexplored. In this study, we show that pretreatment with baicalin has a dose-dependent inhibitory effect on PDGF-BB-stimulated VSMC pro- liferation, accompanied with the reduction of proliferating cell nuclear antigen （PCNA） expression. We also show that baicalin-induced growth inhibition is associated with a decrease in cyclin E-CDK2 activation and increase in p27 level in PDGF-stimulated VSMCs, which appears to be at least partly mediated by blockade of PDGF recep- tor [~ （PDGFR~）-extracellular signal-regulated kinase 1/2 （ERK1/2） signaling. In addition, baicalin was also found to inhibit adhesion molecule expression and cell migration induced by PDGF-BB in VSMCs. Furthermore, using an animal carotid arterial balloon-injury model, we found that baicalin significantly inhibited neointimal hyperplasia. Taken together, our results reveal a novel function of baicalin in inducing growth arrest of PDGF-stimulated VSMCs and suppressing neointimal hyperplasia after balloon injury, and suggest that the underlying mechanism involves the inhibition of cyclin E-CDK2 activation and the increase in p27 accumulation via blockade of the PDGFR^-ERK1/2 signaling cascade.

Altered serum level of cartilage oligomeric matrix protein and its association with coronary calcification in patients with coronary heart disease

Background Cartilage oligomeric matrix protein （COMP） is mainly found in the skeletal system and vascular smooth muscle cells. Recent researches showed that it had a protective function on blood vessels and could also inhibit vascular calcification. We investigated the serum COMPs in coronary heart disease （CHD） patients, and the relationship between serum COMP and the calcification of coronary artery. Methods A total of 233 consecutive chest pain patients who first underwent coronary angiography followed by multi-slice computed to- mography （MSCT） within six months were recruited and divided into two groups according to the coronary angiography luminal diameter narrowing percentages： CHD group （diameter narrowing 〉 50%, n = 194） and control group （diameter narrowing 〈 50%, n = 39）. The Gen- sini score, Syntax score and coronary artery calcium score （CACs） were calculated. The serum COMP level was determined using ELISA. Results The levels of COMP were significantly higher in the CHD group than in the control group 155.7 （124.5-194.5） ng/mL vs. 128.4 （113.0-159.9） ng/mL, P = 0.019. There were no correlation between COMP, Gensini score, Syntax score, severity of coronary stenosis and the number of coronary artery with stenosis 〉 50%. The serum COMP was correlated with age （r = 0.294, P 〈 0.001）, fasting glucose （r = 0.163, P = 0.015）, HbAlc （r = 0.194, P = 0.015） and CACs （r = 0.137, P = 0.037）. Stepwise linear regression analysis showed that COMP level and age were independent predictors of CACs in the CHD patients （fl = 0.402, t = 2.612, P = 0.015; fl = 0.472, t = 3.077, P = 0.005）. Performance of COMP for predicting CHD was shown as area under curve （AUC）： 0.632, 95% CI： 0.549-0.715 and upper tertile CACs was AUC： 0.602, 95% CI： 0.5264）.678 in receiver operating characteristic （ROC） curve analysis. Conclusion Calcification of coronary artery was an independent predictor of serum COMPs.

Yangxueqingnao particles inhibit rat vascular smooth muscle cell proliferation induced by lysophosphatidic acid

Objective: To observe the effect of Yangxueqingnao particles on rat vascular smooth muscle cell (VSMC) prolif- eration induced by lysophosphatidic acid (LPA). Methods: The amount of 3H-TdR (3H-thymidine) admixed in cultured rat VSMC was measured and mitogen-activated protein kinase (MAPK) activity and lipid peroxidation end product malondialdehyde (MDA) content of the VSMC were assayed. Results: 1×10?9, 1×10?8, 1×10?7 mol/L LPA in a concentration dependent manner, induced the amount of 3H-TdR admixed, MAP kinase activity, and MDA content of the cultured rat VSMC to increase. However, 5%, 10%, and 15% Yangxueqingnao serum preincubation resulted in a decrease of 23.0%, 42.0%, and 52.0% (P<0.01) respectively in the amount of 3H-TdR admixed, a decline in VSMC MAP kinase activity of 13.9% (P<0.05), 29.6% (P<0.01), and 48.9% (P<0.01) respectively, and also, a decrease in MDA content of VSMC of 19.4%, 24.7%, and 43.2% (P<0.01) respectively, in the 1×10?7 mol/L LPA-treated VSMC. Conclusions: LPA activates the proliferation and lipid peroxidation of VSMC in a concentration dependent manner. The LPA-induced VSMC proliferation is related to the activity of MAP kinases, enzymes involved in an intracellular signalling pathway. The results of the present study showed that Yangxueqingnao particles can effectively inhibit LPA-induced VSMC proliferation, MAP kinase activation, and reduce lipid peroxidative lesion.

Rosuvastatin inhibits the smooth muscle cell proliferation by targeting TNFα mediated Rho kinase pathway

Objective To investigate whether Tumor Necrosis Factor-alpha （TNFα） is capable of activating Rho kinase pathway which leads to smooth muscle cell proliferation and the intervention function of Rosuvastatin, and clarify the mechanism and intervention manner of anti-atherosclerosis by Rosuvastatin. Methods Wistar neonate rat smooth muscle cells were cultured, and the activity of cell proliferation was determined by methyl thiazolyl tetrazolium （MTT）. The expression of Rho kinase genes after the stimulation of TNFα was evaluated by RT-PCR. Western blot method was used to measure the protein expression of proliferating cell nuclear antigen （PCNA） after TNFα stimulation and Rosuvastatin intervention in smooth muscle cell. Results The TNFα stimulation significantly enhanced the expression of Rho kinase and increased the expression of PCNA protein in smooth muscle cells （P 〈 0.05）. These effects were positively correlated with prolonged treatment whereas additional Rosuvastatin administration inhibited the above-mentioned effects （P 〈 0.05）. Conclusions The activation of TNFα mediated Rho kinase signaling pathway can significantly promote smooth muscle cell proliferation, and Rosuvastatin can not only inhibit this pathway but also the induced proliferation.

Glycation of high-density lipoprotein triggers oxidative stress and promotes the proliferation and migration of vascular smooth muscle cells

Background In type 2 diabetes mellitus （T2DM）, high-density lipoprotein （HDL） impairs its anti-atherogenic properties and even develops to a pro-inflammatory and pro-atherogenic phenotype because of abnormal compositions and modifications. In this study, we ex- amined the effects and the related mechanisms of glycation of HDL on the proliferation and migration of vascular smooth muscle cells （VSMCs）. Methods ＆ Results Glycated HDL （G-HDL） was modified with D-glucose （25 mmol/L） in vitro. Diabetic HDL （D-HDL） was isolated from T2DM patients. Rat VSMCs were isolated from the thoracic aortas. Human VSMCs were obtained from ScienCell Research Laboratories. Alpha-actin was detected through immunofiuorescence. VSMC proliferation was assayed by Cell Count. VSMC migration was determined by transwell chamber and scratch-wound assay. Intracellular reactive oxygen species （ROS） was detected based on ROS-medi- ated 2＇,7＇-dichlorofluorescein （DCFH-DA） fluorescence. Compared to native HDL （N-HDL）, G-HDL remarkably promoted VSMC prolif- eration and migration in the dose and time-dependent manners. In addition, G-HDL enhanced ROS generation in VSMCs. However, the ROS scavenger, N-acetylcysteine, efficiently decreased ROS production and subsequently inhibited the proliferation of VSMCs induced by G-HDL. Similarly, D-HDL from T2DM patients also promoted ROS release and VSMC proliferation and migration. Conclusions HDL either glycated in vitro or isolated from T2DM patients triggered VSMC proliferation, migration, and oxidative stress. These results might partly interpret the higher morbidity of cardiovascular disease in T2DM patients.

INTERLEUKIN 10 INHIBITS THE RAT VSMC PROLIFERATION AND COLLAGEN SECRETION STIMULATED BY ANGIOTENSIN II

Objective. To study the effect of interleukin 10 (IL- 10) on the angiotensin II (AngII) stimulated rat VSMC proliferation and collagen secretion, and furthermore, explore its mechanism. Methods. On cultured VSMC of rat, 3H- thymine (3H- TdR) and 3H- proline incorporations were used to evaluate the DNA and collagen synthesis, respectively. Western blot and immunoprecipitation were applied to assay the expression and activity of focal adhesion kinase (FAK), respectively. Results. IL- 10 (10－ 8～ 10－ 10g/ml) inhibited the increase of 3H- TdR and 3H- proline incorporation as well as FAK activity, which was induced by 10－ 7mol/L AngII (P< 0.05 or P< 0.01). IL- 10 also obviously downregulated the synthesis and secretion of collagen by AngII stimulated VSMC. But there was no difference in the protein expression of FAK among all the groups (P >0.05). Conclusion. IL- 10 antagonizes the VSMC proliferation and collagen synthesis by regulating FAK activity stimulated by AngII.

A case of hepatic angiomyolipoma difficult to distinguish from hepatocellular carcinoma

We report a case of hepatic angiomyolipoma with uncommon clinical features. A 56-year-old man presented with a hepatic tumor in the caudate lobe. The tumor was hypoechoic on ultrasonography, showed early-phase hyperattenuation on enhanced computed tomography and did not absorb iron on superparamagnetic iron oxide-enhanced magnetic resonance imaging. Hepatocellular carcinoma was highly suspected, and the patient underwent hepatic resection. Histologically, the tumor was mainly composed of smooth muscle cells and contained small amounts of adipose cells and blood vessels. On immunohistochemical staining, the smooth muscle cells were positive for a melanocytic cell-specific monoclonal antibody. In cases with uncommon features of angiomyolipoma, it is quite difficult to distinguish angiomyolipoma from hepatocellular carcinoma.

Up-regulation of Fas Ligand Expression by Sirtuin 1 in both Flow-restricted Vessels and Serum-stimulated Vascular Smooth Muscle Cells

Objective To study the role of sirtuin 1 （SIRT1） in Fas ligand （FasL） expression regulation during vascular lesion formation and to elucidate the potential mechanisms. Methods SIRT1 and FasL protein levels were detected by Western blotting in either mouse arteries extract or the whole rat aortic vascular smooth muscle cell （VSMC） lysate. Smooth muscle cell （SMC）-specific human SIRT1 transgenic （Tg） C57BL/6 mice and their littermate wild-type （WT） controls underwent complete carotid artery ligation （ligation groups） or the ligation-excluded operation （sham groups）. The carotid arteries were collected 1 day after operation. Reverse transcription-polymerase chain reaction was performed to detect the mRNA levels of SIRT1 and FasL. Luciferase reporter assays were performed to detect the effect of WT-SIRT1, a dominant-negative form of SIRT1 （SIRT1H363Y）, and GATA-6 on the promoter activity of FasL. Flow cytometry assay was applied to measure the hypodiploid DNA content of VSMC so as to monitor cellular apoptosis. Results SIRTI was expressed in both rat aortic VSMCs and mouse arteries. Forced SIRT1 expression increased FasL expression both in injured mouse carotid arteries 1 day after ligation （P〈0.001） and VSMCs treated with serum （P〈0.05 at the transcriptional level, P〈0.001 at the protein level）. No notable apoptosis was observed. Furthermore, transcription factor GATA-6 increased the promoter activity of FasL （P〈0.001）. The induction of FasL promoter activity by GATA-6 was enhanced by WT-SIRT1 （P〈0.001）, while SIRT1H363Y significantly relieved the enhancing effect of WT-SIRT1 on GATA-6 （P〈0.001）. Conclusions Overexpression of SIRT1 up-regulates FasL expression in both flow-restricted mouse carotid arteries and serum-stimulated VSMCs. The transcription factor GATA-6 participates in the transcriptional regulation of FasL expression by SIRT 1.

Effect of serum concentration on adhesion of monocytic THP-1 cells onto cultured EC monolayer and EC-SMC co-culture

Background:The adhesion of monocytes to the endothelium following accumulation of low-density lipoprotein (LDL) in subendothelial spaces is an important step in the development of intimal hyperplasia in arterially implanted vein grafts and atherosclerosis in both animals and humans. However, it is not well known how serum factors affect the adhesion of monocytes. Methods: We have studied the effect of fetal calf serum (FCS), which we considered a source of LDL, on the adhesion of monocytes to endothelial cells (ECs) by using human monocytic THP-1 cells and both a monolayer of cultured bovine aortic endothelial cells (EC monoculture) and a co-culture with bovine aortic smooth muscle cells (EC-SMC co-culture). Results: It was found that the addition of FCS to the medium greatly affected the adhesion of THP-1 cells, and the higher the concentration of FCS in the medium, the greater the adhesion of THP-1 cells to endothelial cells. Adhesion of THP-1 cells to an EC-SMC co-culture was approximately twofold greater than that to an EC monoculture, and after adhering to endothelial cells, many THP-1 cells trans-migrated into the layer of smooth muscle cells. Conclusion: The results suggest that the elevation of the LDL (cholesterol) level in blood provides a favorable condition for the development of intimal hyperplasia and atherosclerosis by promoting the adhesion of monocytes to the endothelium and their subsequent migration into subendothelial spaces.

Spontaneous Ca^(2+ )oscillations in subcellular compartments of vascular smooth muscle cells rely on different Ca^(2+) pools

Spontaneous Ca2+ oscillations in vascular smooth muscle cells have been modeled using a single Ca2+ pool. This report describes spontaneous Ca2+ oscillations dependent on two separate Ca2+ sources for the nuclear versus cytoplas- mic compartments. Changes in free intracellular Ca2+ were monitored with ratiometric Ca2+- fluorophores using confo- cal microscopy. On average, spontaneous oscillations developed in 79% of rat aortic smooth muscle cells that were synchronous between the cytoplasm and nucleus. Reduction of extracellular Ca2+ (< 1 μM) decreased the frequency and amplitude of the cytoplasmic oscillations with 48% of the oscillations asynchronous between the nuclear and cytoplasmic compartments. Similar results were obtained with the Ca2+ channel blockers, nimodipine and diltiazem. Arg-vasopressin (AVP) induced a rapid release of intracellular Ca2+ stores that was greater in the nuclear compartment (4.20 ± 0.23 ratio units, n = 56) than cytoplasm (2.54 ± 0.28) in cells that had spontaneously developed prior oscillations. Conversely, cells in the same conditions lacking oscillations had a greater AVP-induced Ca2+ transient in the cytoplasm (4.99 ± 0.66, n = 17) than in the nucleus (2.67 ± 0.29). Pre-treatment with Ca2+ channel blockers depressed the AVP responses in both compartments with the cytoplasmic Ca2+ most diminished. Depletion of internal Ca2+ stores prior to AVP exposure blunted the nuclear response, mimicking the response of cells that lacked prior oscillations. Spontaneous oscillating cells had a greater sarcoplasmic reticulum network than cells that did not oscillate. We propose that sponta- neous nuclear oscillations rely on perinuclear sarcoplasmic reticulum stores, while the cytoplasmic oscillations rely on Ca2+ influx.

LOW-DOSE RADIOACTIVE ENDOVASCULAR STENTS PREVENT NEOINTIMAL HYPERPLASIA IN RABBITS RESTENOSIS MODEL

Objective To evaluate the effects of low-dose radioactive stents on the prevention of restenosis in rabbit model. Methods The stents were bombarded with suitable charged particles of adapted energy in the cyclotron to create a proper mixture of the radionuclides 59 Fe, 60 Co, 58 Co, 51 Cr, and 54 Mn. The radioactive stents were implanted in the iliac arteries of rabbits. The effects of radioactive stents on prevention of restenosis were assessed by angiography, histomorphometry and immunocytochemistry. Results All the iliac arteries that had been implanted with radioactive stents were patent on angiography and had no radiation complication during the 1～2 months of follow-up. There was a significant reduction in neointimal area (0.37±0.14mm 2 vs. 0.81±0.10mm 2, P<0.01), percent area stenosis (6.7±2.9% vs. 13.2±1.4%, P<0.01) and PCNA immunoreactive rate (2.00±1.58% vs. 10.88±6.98%, P<0.05) in the radioactive stent group compared with the control stent group. Conclusion Radioactive stents with an active of 0.91～1.65 μCi could inhibit SMC proliferation and neointimal hyperplasia in animal restenosis model. The low-dose radioactive stents are safe and feasible for prevention of restenosis.

Increased expression of inflammation cytokines in senescent vascular smooth muscle cells by balloon catheter denudation is associated with NF-[kappa]B pathway

Objective： To determine whether balloon catheter denudation can induce vascular smooth muscle cells （VSMCs） to senescence, and whether this senescence can result in inflammation activity. Methods： Twelve male Chinese white rabbits were denuded of the carotid arteries or VSMCs. Acidic β-galactosidase activity of carotid arteries or VSMCs was detected. Transfection and chloramphenicol acetyltransferase （CAT） assay for iNOS gene and nitrite （NO2^-） assay were undertaken. Reverse transcription-polymerase chain reaction （RT-PCR） was used to evaluate inflammation cytokines mRNA expression. Measurement of NF-kB activity was detected by electrophoretic mobility shift assay （EMSA）. MMP-9, ICAM-1, P-p65, and IkBα expressions were analyzed by Western blotting. Results： After denudation VSMCs from denuded arteries showed an accumulation of significantly more senescence-associated β-galactosidase （SA-β-Gal） positive ceils and greater iNOS activity. Transcriptional activity of iNOS was highly expressed. The mRNA expressions of IL-1β, ICAM-1,MMP-9, TNF-α and the iNOS enzyme were significantly increased in injuring-induced senescence SMCs. However, the TNF-α or IL-1β-induced the protein production （ICAM-1 and MMP-9） was prevented by PDTC and MG132, which are inhibitors of NF-kB activation. Also, activation of NF-kB and cytokine-induced degradation of IKBα in the denuded VSMC were significantly affected. Conclusion： Intraluminal injury to the artery may lead to the emergence of senescent VSMC. Inflammation activity in SMCs is closely related to the senescence and the activation of NF-kB is involved.

INHIBITORY EFFECT OF ANGIOTENSIN II TYPE 1 RECEPTOR-ASSOCIATED PROTEIN ON VASCULAR SMOOTH MUSCLE CELL GROWTH AND NEOINTIMAL FORMATION

Objective To investigate the mechanism of a novel angiotensin Ⅱ type 1 receptor-associated protein （ATRAP） interfering with angiotensin Ⅱ type 1 （AT1） receptor-mediated vascular smooth muscle cell （VSMC） growth and neointimal formation. Methods VSMCs isolated from thoracic aorta of adult Sprague-Dawley （SD） rats were used in this study. ATRAP cDNA was subcloned into pcDNA3 vector and then transfected into VSMCs. DNA synthesis and extracellular signal-regulated kinase （ERK） and phospho-ERK expressions in VSMCs were assayed by measurement of ^3H thymidine incorporation and Western blotting, respectively. Morphological changes were observed in the balloon injured artery with or without transfection of ATRAP cDNA using 12-week-old male SD rats. Results ATRAP overexpression in VSMCs inhibited angiotensin Ⅱ （Ang Ⅱ）-induced ^3H thymidine incorporation 48 hours after Ang Ⅱ stimulation （ P 〈 0. 05 ）. In VSMC, Ang Ⅱ stimulation increased the phosphorylation of ERK, which reached the peak around 60 minutes. The activation of phospho-ERK was significantly decreased by ATRAP （ P 〈 0. 05 ）. Neointimal formation was markedly inhibited by ATRAP overexpression in injuried arteries.Conclusions The AT1 receptor-derived activation of ERK plays an essential role in Ang Ⅱ-induced VSMC growth. The growth inhibitory effects of ATRAP might be due to interfering with AT1 receptor-mediated activation of ERK in VSMC growth and neointimal formation.

Changes of Ca^2+ activated potassium channels and cellular proliferation in autogenous vein grafts

Objective: To investigate changes of Ca2+ activated potassium channels (KCa) in autogenous vein grafts. Methods: Contraction of venous ring was measured by means of perfusion in vitro. The intimal rabbits proliferation of vascular and proliferation of cultured smooth muscle cells(vascular smooth muscle cells, VSMCs)were observed by the means of computerised image analysis and MTT method respectively. Furthermore, whole cell mode of patch clamp was used to record KCa of VSMCs isolated from autogenous vein grafts. Results: One week after transplantation there were no significant differences of contraction and intimal relative thickness between autogenous vein grafts and control. Contraction and intimal relative thickness of autogenous vein graft were significantly increased 2 weeks after transplantation (P<0.05, n=8 vs control), and they was more enhanced 4 weeks after vein transplantation (P<0.01, n=8 vs control).TEA(blocker of Ca2+ activated potassium channels)increased MTT A490 nm value of VSMCs from femoral vein in a dose dependent manner(P<0.05, n=8). KCa current density was significantly attenuated in VSMCs from autogenous vein grafts (1-4) week after transplantation(P<0.05, n=5).Conclusion: KCa is inhibited in autogenous vein graft, which account for vasospasm and intimal proliferation.

Suppression of angiotensin Ⅱ stimulated responses in aortic vascular smooth muscle cells of experimental cirrhotic rats

Functional responses to angiotensin Ⅱ (AT-Ⅱ) were determined in aortic vascular smooth muscle cells (VSMCs) from experimental cirrhotic rats. Our data showed that AT-Ⅱ-stimulated extracellular acidification rate (ECAR), which was measured by Cytosensor microphysiometry, was significantly reduced in the aortic VSMCs from the cirrhotic rats as compared to those from the control animals. The ability of AT-Ⅱ to promote formation of inositol phosphates, the second messenger produced by the activation of Gq-coupled receptors, was also considerably suppressed in the cirrhotic VSMCs. Furthermore, the maximal p42/44 MAPK phosphorylation stimulated by AT-Ⅱ was significantly reduced in the cirrhotic VSMCs in contrast to that in the normal VSMCs. Taken together, our data clearly demonstrated that the functional responses to AT-Ⅱ was severely suppressed in aortic VSMCs in cirrhosis, indicating the impairment of general Gq-coupled receptor signaling and subsequent biological function in the cirrhotic VSMCs.