Rutaecarpine Inhibits Angiotensin Ⅱ-Induced Proliferation in Rat Vascular Smooth Muscle Cells

Objective： To evaluate the effects and possible mechanisms of rutaecarpine on angiotensin Ⅱ （Ang Ⅱ ）-induced proliferation in cultured rat vascular smooth muscle cells （VSMCs）. Methods： VSMCs were isolated from Male Sprague-Dawley rat aorta, and cultured by enzymic dispersion method. Experiments were performed with cells from passages 3-8. The cultured VSMCs were randomly divided into control, model （Ang Ⅱ 0.1 μ moVL）, and rutaecarpine （0.3-3.0μmol/L） groups. VMSC proliferation was induced by Ang Ⅱ, and was evaluated by the 3-（4, 5-dimethylthiazol-2-yl）-2, 5-diphenyltetrazolium bromide assay and cell counting. To examine the mechanisms involved in anti-proliferative effects of rutaecarpine, nitric oxide （NO） levels and NO synthetase （NOS） activity were determined. Expressions of VSMC proliferation-related genes including endothelial nitric oxide synthase （eNOS）, and c-myc hypertension related gene-1 （HRG-1） were determined by real-time reverse chain reaction （RT-PCR）. Results： Rutaecarpine （0.3-3.0μmol/l_） inhibited Ang R-induced VSMC proliferation and the best effects were achieved at 3.0 μmol/L. The Ang Ⅱ-induced decreases in cellular NO contents and NOS activities were antagonized by rutaecarpine （P〈0.05）. Ang Ⅱ administration suppressed the expressions of eNOS and HRG-1, while increased c-myc expression （P〈0.05）. All these effects were attenuated by 3.0μmol/L rutaecarpine （P〈0.05）. Conclusion： Rutaecarpine is effective against Ang Ⅱ-induced rat VSMC proliferation, and this effect is due, at least in part, to NO production and the modulation of VMSC proliferation-related gene expressions.

Rutaecarpine Inhibits Intimal Hyperplasia in A Balloon-Injured Rat Artery Model

Objective： To investigate the effect and potential mechanisms of rutaecarpine （Rut） in a rat artery balloon-injury model. Methods： The intimal hyperplasia model was established by rubbing the endothelia with a balloon catheter in the common carotid artery （CCA） of rats. Fifty rats were randomly divided into five groups, ie. sham, model, Rut （25, 50 and 75 mg/kg） with 10 rats of each group. The rats were treated with or without Rut （25, 50, 75 mg/kg） by intragastric administration for 14 consecutive days following injury. The morphological changes of the intima were evaluated by hematoxylin-eosin staining. The expressions of proliferating cell nuclear antigen （PCNA） and smooth muscle （SM） oL-actin in the ateries were assayed by immunohistochemical staining. The mRNA expressions of c-myc, extracellular signal-regulated kinase 2 （ERK2）, MAPK phosphatase-1 （MKP-1） and endothelial nitric oxide synthase （eNOS） were determined by real-time reverse chain reaction. The protein expressions of MKP-1 and phosphorylated ERK2 （p-ERK2） were examined by Western blotting. The plasma contents of nitric oxide （NO） and cyclic guanosine 3＇,5＇-monophosphate （cGMP） were also determined. Results： Compared with the model group, Rut treatment significantly decreased intimal thickening and ameliorated endothelial injury （P〈0.05 or P〈0.01）. The positive expression rate of PCNA was decreased, while the expression rate of SM α -actin obviously increased in the vascular wall after Rut （50 and 75 mg/kg） administration （P〈0.05 or P〈0.01）. Furthermore, the mRNA expressions of c-myc, ERK2 and PCNA were downregulated while the expressions of eNOS and MKP-1 were upregulated （P〈0.05 or P〈0.01）. The protein expressions of MKP-1 and the phosphorylation of ERK2 were upregulated and downragulated after Rut （50 and 75 mg/kg） administration （P〈0.05 or P〈0.01）, respectively. In addition, Rut dramatically reversed balloon injury-induced decrease of NO and cGMP in the plasma （P〈0.05 or P〈0.01）. Conclusion： Rut could inhibit the balloon injury-induced carotid intimal hyperplasia in rats, possibly mediated by promotion of NO production and inhibiting ERK2 signal transduction pathways.