大鼠颈动脉球囊损伤后血管平滑肌细胞E1A激活基因阻遏子的表达变化

目的探讨血管再狭窄发生的病理生理机制及E1A激活基因细胞阻遏子(CREG)在新生内膜增殖中的调控作用, 为研究CREG防治增生性血管疾病的作用奠定基础.方法采用大鼠颈动脉球囊损伤后血管再狭窄的动物模型, 以免疫组织化学染色、逆转录-聚合酶链反应(RT-PCR)方法, 检测新生内膜中增殖细胞核抗原(PCNA)和平滑肌α肌动蛋白(SM α-actin)的表达变化及血管壁中CREG mRNA水平、蛋白表达的动态变化.结果大鼠颈动脉球囊损伤后1 d血管壁 CREG mRNA水平开始下降, 至损伤后5 d达最低, 损伤后7 d CREG mRNA表达回升, 至28 d时仍未回到正常对照组的水平.血管损伤后3 d血管内表面可见增殖的血管平滑肌细胞(VSMC), PCNA染色阳性, 其胞浆内SM α-actin和CREG染色均为阴性; 损伤后5 d新生内膜形成并增厚, PCNA阳性细胞数达到高峰, 部分VSMC胞浆内SM α-actin和CREG染色均呈阳性; 损伤后28 d管腔严重狭窄, 新生内膜中PCNA表达已较低, SM α-actin和CREG表达均明显增加, 新生内膜SM α-actin表达程度仍弱于中膜, CREG表达程度接近中膜.损伤后不同时间点VSMC增殖程度与血管壁中CREG mRNA水平的变化呈负相关(r=-0.80, P<0.05), CREG mRNA的表达为先降低, 后回升, 而细胞增殖指数为先升高, 后回降.结论 VSMC的表型转化、增殖、迁移和分泌细胞外基质导致新生内膜过度增生和管腔狭窄, CREG参与VSMC增殖的调控.     

全反式维甲酸对球囊剥脱大鼠胸主动脉内皮后平滑肌细胞增殖和P21表达的影响

目的：探讨全反式维甲酸（ATRA）对球囊损伤大鼠胸主动脉后管腔狭窄、血管平滑肌细胞（VSMC）增殖及细胞周期依赖性激酶抑制蛋白P21表达规律的影响。方法：54只SD大鼠随机分为三组。对照组不进行球囊损伤，术后28天处死；手术组和ATRA治疗组行球囊剥脱胸主动脉内皮术，分别于术后2d、7d、14d、28d处死。取胸主动脉应用HE染色、免疫组化和计算机图像分析法进行形态学、PCNA和P21表达水平检测。结果：①正常动脉壁不表达PCNA及P21。②手术组中膜VSMC术后2d PCNA表达达高峰，后迅速下降；而新生内膜在术后7d现并高表达PCNA，14d、28d内膜迅速增厚，其中PCNA表达逐渐下降。P21在术后14d新生内膜中可见少量表达，28d表达增多。③ATRA治疗组术后7d新生内膜中已有P21表达，14d、28d大量表达，而PCNA的表达明显低于手术组，显著抑制VSMC的迁移和增殖、内膜增生和管腔狭窄（P〈0．01）。④P21表达与PCNA表达呈负相关（P〈0．001）。结论：ATRA可通过诱导P21蛋白表达，抑制VSMC迁移和增殖，从而抑制球囊剥脱大鼠胸主动脉内皮后新生内膜过度增生和管腔狭窄。     

球囊损伤兔腹主动脉壁PTEN的表达变化

目的探讨PTEN在经皮冠状动脉介入治疗（PCI）术后冠状动脉再狭窄形成过程中的作用。方法建立兔腹主动脉球囊损伤模型,采用HE染色方法观察血管新生内膜增生情况,采用免疫组化和Western blot法检测血管壁PTEN蛋白的表达。结果与假手术组相比,球囊损伤后腹主动脉新生内膜面积逐渐增加,壁内PTEN表达减少（P〈0.01）,但新生内膜层的PTEN表达水平高于中膜层（P〈0.01）。结论PTEN的表达变化可能参与了血管损伤后的修复反应,与PCI术后冠状动脉再狭窄的发生、发展有关。     

苯磺酸氨氯地平抑制损伤诱导的血管新生内膜形成

目的 研究苯磺酸氨氯地平(AM)、阿托伐他汀(AT)单独及联合用药对球囊损伤诱导的血管新生内膜形成影响及机制.方法 复制颈总动脉球囊损伤模型,分离颈总动脉制备病理切片,HE染色观察内膜增生情况.免疫组化观察增殖、迁移相关蛋白表达情况.贴块法培养血管平滑肌细胞(VSMC),待生长至70％～ 80％融合时,分别加入不同浓度苯磺酸氨氯地平,继续孵育24 h,细胞计数及Western印迹法用于分析VSMC增殖活性;伤口愈合实验及明胶酶图实验用于分析VSMC迁移活性.结果 AM抑制球囊损伤诱导的血管新生内膜形成和管腔狭窄,与AT联用增强其抑制效果;AM单独及与AT联合用药抑制球囊损伤诱导的PCNA、KLF5、MMP-9 的表达;AM抑制体外培养的VSMC中PCNA、KLF5和c-Jun的表达;降低MMP-2和MMP-9的活性.结论 AM抑制球囊损伤诱导的血管新生内膜形成与其抑制VSMC增殖及迁移活性有关.     

豁痰通络方对大鼠球囊损伤后内膜增生的干预机制

目的研究豁痰通络方对大鼠颈动脉球囊损伤后内膜增生干预机制的体内免疫学作用。方法建立大鼠颈动脉球囊损伤模型;采用HE染色法观察各组大鼠颈动脉血管变化;采用免疫组化法检测颈动脉组织核转录因子(NF)-κB蛋白的表达;Western印迹法检测豁痰通络方对大鼠颈动脉组织NF-κB p65、IκBα蛋白表达的影响。结果豁痰通络方可显著减轻血管狭窄情况并能够显著降低p-IκB-α、p-p65的蛋白表达量,显著增加IκB-α、p65蛋白的表达。结论豁痰通络方可以有效抑制大鼠颈动脉球囊损伤后新生内膜的增殖,可能通过调控NF-κB信号通路来抑制新生内膜的增殖。     

大鼠血管紧张素Ⅱ2型受体基因转染对颈动脉球囊损伤后新生内膜形成的影响

目的　探讨腺病毒载体介导的大鼠血管紧张素Ⅱ2型受体(AT2R)基因转染对大鼠颈动脉球囊损伤后新生内膜形成的影响。方法　应用带有绿色荧光蛋白报告基因的重组腺病毒载体将大鼠AT2R基因转移至颈动脉球囊损伤模型中,2 1d后取材,应用免疫组织化学方法检测AT2R在动脉壁中的表达,图像分析观察其对新生内膜形成的影响。结果　在体大鼠颈动脉腺病毒载体的转染率达4 0 % ,AT2R基因在血管壁的新生内膜、中膜、外膜稳定表达,转染AT2R基因的球囊损伤后颈动脉与绿色荧光蛋白基因对照组相比,血管新生内膜 中膜面积比降低了4 8%。结论　AT2R基因转染可抑制颈动脉球囊损伤后新生内膜的形成,对血管成形术后再狭窄可能有一定的预防作用。     

核转录因子NF-κB对血管损伤和新生内膜形成的影响

目的:探讨核转录因子NF-κB对血管平滑肌细胞增殖以及大鼠颈动脉球囊损伤后血管新生内膜的作用。方法:原代培养大鼠胸主动脉血管平滑肌细胞。检测增殖的平滑肌细胞内增殖细胞核抗原(PCNA)和NF-κB水平。制作大鼠血管球囊损伤模型,检测血管新生内膜形成及单核细胞化学趋化因子(MCP-1)、NF-κBp65和细胞外信号调节激酶(ERK2)的表达。结果:增殖的平滑肌细胞PCNA和NF-κBp65蛋白水平表达增加。NF-κBp65反义和诱骗寡核苷酸抑制PCNA表达。大鼠血管球囊损伤后第7天,正义组、诱骗对照组、模型组的内膜面积、中膜面积、内膜/中膜比值达到高峰。反义组、诱骗组和反义诱骗组显著降低内膜与中膜比值(P<0.05)。球囊损伤后3d、5d、7d,MCP-1mRNA和蛋白质水平持续而明显的表达增强,14d后略为降低。反义组、诱骗组、反义诱骗组在各时间点均能减少MCP-1mRNA和蛋白质表达。Western Blot检测显示血管球囊损伤后7d,NF-κBp65、ERK2的蛋白合成达到高峰。反义组、诱骗组、反义诱骗组较模型组、正义组、诱骗对照组各时相点蛋白合成均减弱。结论:增殖的平滑肌细胞NF-κBp65基因表达增加。NF-κB调控PCNA、MCP-1、ERK2的基因表达和蛋白质水平。局部转染NF-κB反义和诱骗寡核苷酸能抑制血管新生内膜的形成。     

大鼠胸主动脉球囊损伤后平滑肌细胞PCNA和P27表达的变化

目的探讨大鼠胸主动脉球囊损伤后增殖细胞核抗原(PCNA)、细胞周期蛋白依赖性激酶抑制蛋白P27表达变化规律。方法30只400～500g的雄性SD大鼠随机分为2组。手术组(n=24)行球囊损伤大鼠胸主动脉术;对照组(n=6)不行球囊损伤,作为正常对照。于术后2d、7d、14d、28d取胸主动脉应用HE染色、免疫组化和计算机图像分析法进行形态学、PCNA和P27表达水平检测。结果(1)正常动脉壁不表达PCNA,球囊损伤后开始表达,术后2d时中膜表达显著(24.08±2.35);术后7d出现新生内膜,PCNA在内膜高度表达(35.32±3.46)而中膜表达已明显下降(9.47±1.56);后内膜、中膜表达均逐渐下降,28d时形成显著的新生内膜(0.173±0.030)mm2,管腔狭窄;(2)正常动脉壁显著表达P27(19.29±1.54),球囊损伤后中膜表达迅速下降,2d达最低水平(2.93±0.55),后逐渐回升;14d、28d新生内膜中可见P27表达,并逐渐增多;(3)P27表达与PCNA表达呈显著负相关(r=0.868P<0.001)。结论球囊损伤大鼠主动脉后管壁P27表达下调伴随PCNA表达上调,血管平滑肌细胞恢复增殖能力并向内膜下迁移并过度增殖,从而形成显著的新生内膜、管腔狭窄。     

大鼠胸主动脉球囊损伤对细胞凋亡及凋亡相关基因Fas、Bcl-2表达的影响

目的探讨大鼠胸主动脉球囊损伤后细胞凋亡和凋亡相关基因表达的变化规律。方法将30只400~500 g的雄性SD大鼠随机分为2组,手术组(n=24)行球囊扩张损伤大鼠胸主动脉术;对照组(n=6)不行球囊损伤,作为正常对照。分别于术后2、7、14、28 d取胸主动脉应用HE染色、TUNEL法、免疫组化和计算机图像分析仪进行形态学、细胞凋亡、增殖细胞核抗原(PCNA)、凋亡基因Fas;抗凋亡基因Bcl-2表达水平检测。结果对照组管壁处于非增殖状态;手术组球囊损伤后7 d形成新生内膜,血管平滑肌细胞(VSMC)增殖活跃;14 d内膜明显增厚,但VSMC增殖已减弱;28 d内膜继续缓慢增厚,管腔明显狭窄。动脉损伤后Fas表达和TUNEL法测定的凋亡规律一致,两周内凋亡较明显,但细胞凋亡高峰时间(中膜7 d、内膜14 d)迟于增殖高峰(中膜2 d、内膜7 d),两周后凋亡与增殖均明显下降。动脉损伤后抗凋亡基因Bcl-2表达下调,在中膜和内膜分别在7 d1、4 d达最低水平,后回升,与凋亡基因Fas表达呈明显负相关(r=-0.878,P<0.001)。结论动脉球囊损伤后,平滑肌细胞的凋亡呈现规律性变化,可能在管腔狭窄的病理过程中具有重要作用。     

益心方对球囊损伤后大鼠颈总动脉血管增生的影响

目的探讨颜氏益心方对实验性球囊损伤后大鼠颈动脉增生的影响。方法利用SD大鼠颈总动脉球囊损伤法造成颈动脉狭窄,观察颜氏益心方对血管增殖细胞核抗原(PCNA)、早期生长反应因子-1(Egr-1)、转化生长因子(TGF)-β及血管病理形态的影响。结果与假手术组比较,模型对照组、益心方低、高剂量组各生长因子表达增多(P<0.05);与模型对照组比较,益心方低、高剂量治疗组均能降低各生长因子表达(P<0.05),明显改善内膜增生程度。结论颜氏益心方可降低各生长因子表达,抑制球囊损伤后大鼠颈动脉血管内膜增生。     

Effects of hydroxymethylglutaryl coenzyme A reductase inhibitor simvastatin on smooth muscle cell proliferation in vitro and neointimal formation in vivo after vascular injury

OBJECTIVES: We sought to evaluate the effects of hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase inhibitors on vascular smooth muscle cell (VSMC) proliferation in vitro and neointimal formation in vivo after vascular injury. BACKGROUND: Neointimal hyperplasia after vascular injury is responsible for restenosis after arterial stenting, whereas arterial remodeling and neointimal formation are the causes of restenosis after percutaneous transluminal coronary angioplasty. METHODS: We assessed the effect of simvastatin on in vitro VSMC proliferation. To study the effects of simvastatin in vivo, balloon injury and stent deployment were performed in the common carotid artery of rats. Neointimal area was measured two weeks later in the balloon injury model and three weeks after stent deployment. RESULTS: Simvastatin markedly inhibits VSMC proliferation in vitro. In vivo, simvastatin reduced, in a dose-dependent manner, the neointimal area and the neointima-media ratio after balloon injury from 0.266 +/- 0.015 mm2 to 0.080 +/- 0.026 mm2 and from 1.271 +/- 0.074 to 0.436 +/- 0.158 (p < 0.001 vs. control rats) at the highest dose. Simvastatin also significantly reduced the neointimal formation and the neointima-media ratio after stenting from 0.508 +/- 0.035 mm2 to 0.362 +/- 0.047 mm2 (p < 0.05 vs. control rats) and from 2.000 +/- 0.136 to 1.374 +/- 0.180 (p < 0.05 vs. control rats). The vessel thrombosis rate after stent deployment was 30% in the control group and 11.1% in the treated group (p = NS). Moreover, the systemic administration of simvastatin did not affect hepatic and renal functions, blood pressure or heart rate. CONCLUSIONS: Simvastatin potently inhibits VSMC proliferation in vitro and reduces neointimal formation in a rat model of vascular injury.     

Berberine inhibits rat vascular smooth muscle cell proliferation and migration in vitro and improves neointima formation after balloon injury in vivo. Berberine improves neointima formation in a rat model

Berberine, an alkaloid isolated from Chinese medicinal herbs, long been known for its anti-microbial activity and used to treat various infectious disorders in traditional Chinese medicine. In the present study, we have tested the hypothesis that berberine could inhibit vascular smooth muscle cell (VSMC) proliferation as it did in endothelial cells or cancer cells. Our results show that berberine significantly inhibits growth factor, mainly angiotensin II (AngII) and heparin binding epidermal growth factor (HB-EGF), induced VSMC proliferation and migration in vitro, and this effect is achieved by delaying or partially suppressing activation of Akt pathway rather than ERK pathway. Furthermore, we have examined its effect in vivo using a rat carotid artery injury model. A 28 days of chronic berberine treatment using an osmotic pump (100 microg kg(-1)d(-1), 2 weeks before and 2 weeks after the injury) improved neointima formation. The Neointima/Media ratio for control group and berberine treated group were 1.14+/-0.11 and 0.85+/-0.06 (p<0.05), respectively, and the reduction was approximately 25%. The result of the present study suggests a possibility of berberine being a potent agent to control restenosis after balloon angioplasty and warrants further study to gain a more complete understanding of its underlying mechanisms at a cellular level.     

Roscovitine抑制大鼠颈总动脉球囊损伤后内膜增生的研究

目的:观察roscovitine对球囊损伤后大鼠颈总动脉血管平滑肌细胞及内膜增生的抑制作用,以期提供新型的支架涂层药物。方法:建立大鼠颈总动脉球囊损伤模型模拟经皮冠状动脉腔内介入术(PCI)术后再狭窄,干预组损伤局部给予roscovitine(200μmol/L)孵育10分钟。14天后取材,免疫荧光染色观察roscovitine对局部血管平滑肌细胞增殖的作用;HE染色观察roscovitine对内膜增生的作用。结果:本研究建立了大鼠颈总动脉球囊损伤模型,球囊损伤后14天,局部血管平滑肌细胞增殖活跃、内膜增生明显。Roscovitine干预后,血管平滑肌细胞增殖率明显降低,内膜增生被显著抑制,管腔狭窄率和内膜中膜面积比值显著降低。结论:Roscovitine显著抑制大鼠颈总动脉球囊损伤后局部血管平滑肌细胞增殖,进而有效抑制内膜增生,降低再狭窄发生率。     

Neuregulin-1 attenuates neointimal formation following vascular injury and inhibits the proliferation of vascular smooth muscle cells

Neuregulin-1 (NRG-1) is expressed in vascular endothelial cells, and its receptors are localized to the underlying smooth muscle cells. However, the role of NRG-1 in vascular function and injury is largely unknown. First, the expression of NRG-1 and its receptors (erbB receptors) was analyzed after balloon injury to the rat carotid artery. NRG-1 and erbB expression levels were low in uninjured vessels; however, NRG-1 and erbB4 were upregulated following injury. We then examined the effect of NRG-1 on neointimal formation following balloon injury. NRG-1 was administered by tail-vein injection prior to injury and every 2 days following injury. Two weeks after injury, NRG-1-treated animals demonstrated a 50% reduction in lesion size compared with controls receiving the vehicle. To examine possible mechanisms for NRG-1 action, we examined its effects on vascular smooth muscle cell (VSMC) function. Rat VSMC cultures were pretreated with NRG-1 for 24 h and then stimulated with platelet-derived growth factor. NRG-1 significantly decreased platelet-derived growth factor-stimulated VSMC proliferation and migration. These findings suggest that NRG-1 may be a novel therapeutic candidate for the treatment of restenosis and atherosclerosis.     

ACE-inhibition promotes apoptosis after balloon injury of rat carotid arteries

OBJECTIVE: Angiotensin II stimulates vascular smooth muscle cell (VSMC) growth, and is considered to be an important mediator of intimal thickening after vascular injury. Recent evidence has indicated that VSMC apoptosis plays a major role in the response to balloon injury, and we therefore examined the effect of angiotensin converting enzyme (ACE)-inhibition on VSMC apoptosis and vascular lesion formation in the rat model of balloon injury. METHODS: Male Sprague-Dawley rats were subjected to carotid artery balloon injury and randomised to a standard diet or a diet supplemented with 1 mg/ml captopril in the drinking water. Animals were sacrificed 2 and 14 days after injury for assessment of apoptosis and proliferation by in situ terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labelling (TUNEL) and proliferating cell nuclear antigen (PCNA) immunohistochemistry, respectively. At 14 days post injury, vessel cross-sections were subjected to microscopic morphometry and total cell numbers were determined. RESULTS: At 2 days after balloon injury, captopril-treated animals displayed a significant increase in the percentage of TUNEL-positive VSMCs in the medial area (12 +/- 4% vs. 1 +/- 1%; P < 0.05) as compared to controls. This increase in early apoptosis was associated with decreased intimal cellularity 14 days post injury (238 +/- 47 cells/cross-section vs. 449 +/- 75 cells/cross-section; P < 0.05), and a reduction of neointimal formation (0.13 +/- 0.02 mm2 vs. 0.23 +/- 0.04 mm2; P < 0.05). The fraction of PCNA-positive VSMCs per cross-section 2 or 14 days after injury was not significantly altered by captopril administration. CONCLUSION: Captopril inhibits neointimal formation in the rat model of arterial injury by mechanisms involving induction of VSMC apoptosis.     

Inhibitory effects of novel AP-1 decoy oligodeoxynucleotides on vascular smooth muscle cell proliferation in vitro and neointimal formation in vivo

Excessive proliferation of vascular smooth muscle cells (VSMCs) and neointimal formation are critical steps in the pathogenesis of atherosclerosis and restenosis after percutaneous transluminal angioplasty. In this study, we investigated the hypothesis that the activator protein-1 (AP-1) plays an important role in neointimal formation after vascular injury. A circular dumbbell AP-1 decoy oligodeoxynucleotide (CDODN) was developed as a novel therapeutic strategy for restenosis after angioplasty. This CDODN was more stable than the conventional phosphorothioate linear decoy ODN (PSODN) and maintained structural integrity on exposure to exonuclease III or serum. Transfection with AP-1 decoy ODNs strongly inhibited VSMC proliferation and migration, as well as glucose- and serum-induced expression of PCNA and cyclin A genes. Administration of AP-1 decoy ODNs in vivo using the hemagglutinating virus of Japan (HVJ)-liposome method virtually abolished neointimal formation after balloon injury to the rat carotid artery. Compared with PSODN, CDODN was more effective in inhibiting the proliferation of VSMCs in vitro and neointimal formation in vivo. Our results collectively indicate that AP-1 activation is crucial for the mediation of VSMC proliferation in response to vascular injury. Moreover, the use of stable CDODN specific for AP-1 activity in combination with the highly effective HVJ-liposome method provides a novel potential therapeutic strategy for the prevention of restenosis after angioplasty in humans.     

Physical training increases eNOS vascular expression and activity and reduces restenosis after balloon angioplasty or arterial stenting in rats

The effects of dynamic exercise on restenosis after vascular injury are still unknown. The consequences of balloon dilation-induced injury on neointimal hyperplasia, vascular negative remodeling, and reendothelialization were assessed in sedentary and trained rats. Ex vivo eNOS vascular expression and activity were investigated in carotid arteries isolated from sedentary and exercised rats. The in vivo effects of eNOS inhibition by L-NMMA on vessel wall after balloon dilation were evaluated in sedentary and exercised rats. We also investigated the effects of exercise on neointimal formation in a rat stent model of vascular injury. Compared with sedentary group, the arteries isolated from trained rats showed higher levels of eNOS protein expression and activity 7 days after balloon dilation. A significant reduction of both neointimal hyperplasia and negative remodeling was observed 14 days after balloon injury in trained compared with sedentary rats. Moreover, we demonstrated that exercise training produced accelerated reendothelialization of the balloon injured arterial segments compared with sedentary. L-NMMA administration eliminated the benefits of physical training on vessel wall after balloon dilation. Finally, a decrease of neointimal hyperplasia as well as of platelet aggregation was observed after stent deployment in trained rats compared with sedentary. In conclusion, physical exercise could favorably affect restenosis after balloon angioplasty and stenting. Increase in eNOS expression and activity might contribute to the potential beneficial effects of exercise on the vessel wall after vascular injury.     

反义血管紧张素Ⅱ受体Ⅰ_B基因转移对大鼠颈动脉损伤后新生内膜的影响

目的　探讨腺病毒载体介导的大鼠反义血管紧张素Ⅱ受体ⅠB(AT1B)RNA转移对大鼠颈动脉损伤后新生内膜的影响。方法　利用重组腺病毒载体将大鼠反义AT1B RNA转移至大鼠颈动脉球囊损伤模型中 ,2 1天后观察其对新生内膜形成的影响。结果　用腺病毒载体转导大鼠反义AT1BRNA至大鼠球囊损伤的颈动脉 ,与对照组相比 ,2 1天后损伤血管新生内膜 /中层面积比降低了 4 7%(P <0 0 0 1)。结论　反义AT1BRNA对血管成形术后再狭窄可能有一定的预防作用。     

8-chloro-cAMP inhibits smooth muscle cell proliferation in vitro and neointima formation induced by balloon injury in vivo

OBJECTIVES: The aims of the present study were to assess 1) the effect of 8-C1-cAMP (cyclic-3'-5'-adenosine monophosphate) on vascular smooth muscle cell (VSMC) proliferation in vitro and 2) the efficacy of systemic administration of 8-C1-cAMP on neointimal formation after balloon injury in vivo. BACKGROUND: Neointimal formation after vascular injury is responsible for restenosis after arterial stenting. Recently, 8-C1-cAMP, a cAMP analogue that induces growth arrest, has been safely administered in phase I studies in humans. METHODS: The effect of 8-C1-cAMP on cell proliferation was first assessed on SMCs in vitro. To study the effects of cAMP in vivo, balloon injury was performed in 67 rats using a 2F Fogarty balloon catheter. RESULTS: The 8-C1-cAMP markedly inhibited VSMC proliferation in vitro, reduced protein kinase A (PKA) RIalpha subunit expression, and induced PKA RIIbeta subunit expression. In addition, 8-C1-cAMP reduced, in a dose-dependent manner, neointimal area and neointima/media ratio after balloon injury. The proliferative activity, assessed by proliferating nuclear cell antigen immunostaining, revealed a reduction of proliferative activity of VSMCs in vivo in the 8-C1-cAMP group. Moreover, the systemic administration of 8-C1-cAMP did not affect renal function, blood pressure and heart rate. CONCLUSIONS: We conclude that 8-C1-cAMP potently inhibits VSMC proliferation in vitro and reduces neointima formation by balloon injury in vivo after systemic administration. These data may have a clinical relevance in designing future strategies to prevent restenosis after arterial stenting and perhaps after percutaneous transluminal coronary angioplasty.