Chan Liu

Role of TGF-β1/Smads pathway in carotid artery remodeling in renovascular hypertensive rats and prevention by Enalapril and Amlodipine.

Objective To investigate the role of transforming growth factor-β1 (TGF-β1), Smad2/3 and Smad7 expressions in carotid artery remodeling in renovascular hypertensive rats, and also the therapeutic effect of Enalapril and Amlodipine. Methods The renovascular hypertensive rat (RHR) models with “two-kidney and one-clip” were established, including model group (n = 6), sham-operated group (n = 6), Enalapril group (10 mg/kg per day, n = 6), Amlodipine group (5 mg/kg per day, n = 6) and combination group (Amlodipine 2.5 mg/kg per day + Enalapril 5mg/kg per day, n = 6). The medication were continuous administrated for six weeks. Carotid artery morphological and structural changes in the media were observed by HE staining, Masson staining and immuno histochemical staining. Media thickness (MT), MT and lumen diameter ratio (MT/LD), and the expression levels of media α-smooth muscle actin (α-actin), proliferating cell nuclear antigen (PCNA), TGF-β1, phosphorylated Smad2/3 (p-Smad2/3) and Smad7 in carotid arteries were measured. Results The media of carotid arteries in RHR model group was significantly thickened, the volume of smooth muscle cell was increased, and the array was in disorder; MT, MT/LD, the proliferation index of smooth muscle cell and collagen fiber area percentage of carotid arteries in the model group were significantly higher than those in the sham-operated group (P < 0.01). Compared to sham-operated group, the model group had significantly higher expressions of TGF-β1 and p-Smad2/3 (P < 0.05) and lower Smad7 expression. Both Enalapril and Amlodipine improved smooth muscle hypertrophy and collagen deposition, reduced RHR carotid MT, MT/LD, proliferation index of smooth muscle cell, collagen fiber area percentage and the expressions of TGF-β1 and p-Smad2/3 (P < 0.05), increased Smad7 expression (P < 0.05). Moreover, the combination treatment of Enalapril and Amlodipine had significantly better effects than single Amlodipine group (P < 0.05), but not single Enalapril group. Conclusions TGF-β1/Smads pathway may participate in the mechanism of carotid artery remodeling in RHR; the role of Amlodipine and Enalapril in inversing carotid artery remodeling may be related to the change of TGF-β1/Smads pathway, the combination treatment of Amlodipine and Enalapril had better effects than single administration of Amlodipine.

EFFECTS OF HIGH-SALT DIET ON THE REMODELLING OF CAROTID ARTERIES AND THE INTERVENTION OF TELMISARTAN IN WISTAR RATS

Objectives To study the influence of high salt diet on blood pressure and carotid artery remodelling and the intervention of telmisartan in Wiatar rats. Methods 60 Wistar rats were fed a normal salt diet (Control group, 0.5%NaCl), high salt diet (M group: 8% NaCl), and high salt diet+Telmisartan (Tel group, 8% NaCl+ Telmisartan) until 24 weeks. After the end of experiment, M group was divided into hypertension group (MH) and normal blood pressure group (MN) according of the tail-cuff blood pressure. The structural changes and proliferation in the media of carotid artery were observed by HE staining, Masson staining and immunohistochemical. Expression of TGF-β1, smad2/3, smad7, AngII, AT1 and AT2 in media of carotid arteries were measured with immunohistochemistry method. Aldosterone in vessel was measured by radioimmunoassay. Results (1) Media thickness (MT), ratio of media to lumen (MT/LD), proliferation index (PI)、collagen fibre area percentage of carotid arteries in MH and MN groups were increased compared with that of the control group p<0.01), But MT, MT/LD, PI, the collagen volume fraction in Tel group decreased significantly p<0.01). (2) compared with the control group, the TGF-β1, smad2/3 in MH and MN groups were higher p<0.01), and in Tel group was decreased significantly p<0.01). smad7 of carotid arteries media in control group was increased than in other three groups p<0.01), Tel group was increased significantly compared with MH and MN groups p<0.01). (3) AngII of carotid artery was no difference in each group (p>0.05). The AT1 expression in MH and MN groups were higher than in the control group p<0.01), and were much lower in telmisartan group p<0.01). The AT2 expression in MH was increased significantly compared with that of other three groups p<0.01). The AT2 of expression in MN and Tel group were increased compared with that of the control group p<0.01). The aldosterone level in carotid arteries media was increased in MH groups compared with that of the control group p<0.05). Conclusions Long-term high-salt diet can cause the carotid artery remodelling directly or through high blood pressure, it may be related to positive and negative regulation of signal transduction in TGF-β1/smads and the RAAS components in local tissues. Telmisartan can prevent high salt-induced hypertension and remodelling of carotid artery.

ROLE OF TGF-β1/SMADS PATHWAY IN CAROTID ARTERY REMODELLING AND PREVENTION OF ENALAPRIL AND AMLODIPINE IN RENOVASCULAR HYPERTENSIVE RATS

Objectives To investigate the role of TGF-β1/Smads pathway in carotid artery remodelling in renovascular hypertensive rats and the prevention of enalapril and amlodipine. Methods The renovascular hypertensive rats (RHR) developed by ‘two-kidney and one-clip’ method were treated consecutively with distilled water (model group, n=6), enalapril (10 mg/(kg/d), n=6), amlodipine (50 mg/(kg/d), n=6) for 6 weeks. Six sham-operated rats were used as controls. Carotid artery morphology and structural changes in the media were observed by HE staining, immunohistochemical staining and Masson staining. Media thickness (MT), lumen diameter (LD), media thickness and lumen diameter ratio (MT/LD) and collagen fibre area percentage of carotid arteries were measured. In addition, the immunohistochemical staining was applied to detect the expression of α-smooth muscle actin (α-SMA), proliferating cell nuclear antigen (PCNA), TGF-β1, p-Smad2/3 and Smad7. Results MT, LD, MT/LD, α-SMA, PCNA and collagen fibre area percentage of carotid arteries in the model group were higher than those in the sham-operated group (p<0.01), and TGF-β1 and p-smad2/3 were significantly increased compared to sham-operated group, Smad7 was much lower in the model group (p<0.01). Single therapy of enalapril or amlodipine decreased MT, MT/LD and the protein expression of TGF-β1, p-Smad2/3, and increased the expression of Smad7. The combination treatment of enalapril and amlodipine was significantly better than that in single amlodipine group (p<0.05), but not in single enalapril group. Conclusions In RHR, TGF-β1/Smads pathway may participate in the mechanism of carotid artery remodelling. The enalapril or amlodipine could attenuate carotid remodelling of RHR through the intervention in TGF-β1/Smads pathway. The combination of enalapril and amlodipine is better than amlodipine therapy.

EFFECTS OF ENALAPRIL AND IRBESARTAN ON CAROTID ARTERY REMODELLING AND TGF-β1/SMADS PATHWAY IN RENOVASCULAR HYPERTENSIVE RATS

Objectives To investigate the effects of single-drug or combination therapy of enalapril and irbesartan on carotid artery remodelling and TGF-β1/Smads signal pathway. Methods Renovascular hypertensive rats (RHR) developed by ‘two-kidney and one-clip’ method were treated respectively with distilled water (model group, n=6), enalapril (10 mg/(kg d), n=6), irbesartan (50 mg/(kg/d), n=6) and enalapril plus irbesartan (5 mg/kg/d+25 mg/(kg d), n=6) for 6 weeks. Six sham-operated rats were used as controls. Carotid artery morphology and structural changes were observed through HE staining, immunohistochemical staining and Masson staining. Media thickness (MT), lumen diameter (LD), media thickness and lumen diameter ratio (MT/LD) and collagen fibre area percentage of carotid arteries were measured. Moreover, the immunohistochemical staining was applied to detect the expression of alpha-smooth muscle actin (α-SMA), proliferating cell nuclear antigen (PCNA), TGF-β1, p-Smad2/3 and Smad7. Results In the model group, the media thickness was significantly increased, and the volume of vascular smooth muscle cell (VSMC) increased and disarranged. MT, LD, MT/LD, α-SMA, PCNA and collagen fibre area percentage of carotid arteries in the model group were higher than those in the sham-operated group (p<0.01), and TGF-β1 and p-smad2/3 were increased whereas Smad7 was decreased in the model group (p<0.01). Single enalapril or irbesartan therapy decreased MT, MT/LD and the protein expression of TGF-β1, p-Smad2/3, and increased the expression of Smad7. Combined enalapril and irbesartan treatment showed significant reductions in above experimental indices than single drug interventions (all p<0.05). Conclusions The TGFβ1/Smads signalling pathway may be involved in carotid remodelling of RHR. Enalapril or irbesartan can attenuate carotid remodelling of RHR through regulating TGF-β1/Smads pathway and both combination treatment seems to have interaction.

EFFECTS OF HIGH SALT DIET ON ARTERIAL REMODELLING AND THE INTERVENTION OF TELMISARTAN IN WISTAR RATS

Objectives To investigate the effects of dietary salt on aorta and mesenteric artery remodelling in Wistar Rats and explore the possible mechanism of salt-induced arterial remodelling and AngiotensinII receptor blockers telmisartan intervention. Methods 60 Wistar rats were randomly divided into normal control group, high salt (8%) model group and high salt+telmisartan group. The tail artery pressure was determined every 2 weeks. After 24 weeks, high salt model group was divided into model hypertension (MH) group and model normal pressure (MN) group. The structural changes and proliferation in the media of aorta and mesenteric arteries were observed by HE staining, Masson staining and immunohistochemical staining. The activities and mRNA levels of Na+ pump and Ca2+ pump in aortic media were determined by enzyme colorimetry and real-time PCR respectively. Results Compared with control group, the blood pressure was significantly increased in MH Group, Media thickness (MT), lumen diameter (LD), ratio of media to lumen (MT/LD), the collagen volume fraction and PCNA positive expressive percentage of arteries in high-salt group were increased (p<0.05), the activities of Na+-K+-ATPase and Ca2+-ATPase in MH group were decreased (p<0.05).The mRNA expression of Na+-K+-ATPase α1 subunit in MH and MN groups was decreased (P<0.05), and PMCA1 expression raised in MH group, Correlation analysis showed that two ATPase activities and vascular remodelling indicators have a negative correlation (p<0.05).Compared with high-salt group, blood pressure, media thickness, ratio of media to lumen, the collagen volume and PCNA positive expressive percentage were lower in telmisartan group (p<0.05). Conclusions High-salt diet could lead to arterial remodelling directly or indirectly (elevated blood pressure), The decreased ion pump activity and abnormal gene expression may be one of the mechanisms of high-salt induced arterial remodelling. Telmisartan may inhibit the proliferation of vascular smooth muscle and collagen accumulation, and prevent salt-induced hypertension and arterial remodelling.