Qin Wu

e0039 Effects of Lisinopril on the activities and mRNA expression of ion pumps in aortic smooth muscle cells from spontaneously hypertensive rats

Objectives To explore the effects of Lisinopril upon the activities of Na+, K+-ATPase and Ca2+-ATPase and mRNA expression levels of Na+, K+-ATPase a1-subunit and plasma membrane Ca2+-ATPase isoform 1 (PMCA1) in cultured thoracic aorta vascular smooth muscle cells (ASMCs) isolated from spontaneously hypertensive rats (SHR). Methods ASMCs were divided into four groups: Wistar-Kyoto (WKY) control, SHR control, Lisinopril (1×10−5) intervened SHR group and Lisinopril (1×10−6) intervened SHR group. The activities of ion pumps were detected by spectrophotography and mRNA expressions were measured by real time PCR. The content of Angiotensin II (Ang II) in cells-cultured medium were detected by radioimmunoassay. Results The activities of Na+, K+-ATPase, Ca2+-ATPase and the mRNA expression levels of Na+, K+-ATPase a1-subunit and PMCA1 in ASMCs from SHR were significantly lower than those from WKY control (p<0.01). Lisinopril significantly increased the activities of Na+, K+-ATPase and Ca2+-ATPase and mRNA expression levels of Na+, K+-ATPase a1-subunit and PMCA1 in ASMCs from SHR (p<0.01). Ang II content of culture medium in ASMCs from SHR was significantly more than those from WKY control (p<0.05), Lisinopril attenuated Ang II content of ASMCs culture medium from SHR (p<0.05). Conclusions The decreased activities of Na+, K+-ATPase and Ca2+-ATPase may be related to their lower expression of the mRNA in ASMCs from SHR. The Lisinopril may increase the activities of two ion pumps and upregrulae the mRNA expression of Na+, K+-ATPase a1-subunit and PMCA1 in ASMCs from SHR through blocking the generation of Ang II.

EFFECTS OF HIGH-SALT DIET ON MYOCARDIAL REMODELLING AND THE INTERVENTION OF TELMISARTAN

Objectives To study the effects of high-salt diet on myocardial remodelling, and investigate the relevant mechanisms of telmisartan on the reverse of myocardial remodelling in Wistar rats. Methods Twenty-four Wistar rats fed by high-salt diet for 23u2005weeks which were divided into two groups: high-salt hypertension group (HSH n=12) and high-salt normal blood pressure group (HSN n=12) according to the level of systolic blood pressure (SBP). The rats of telmisartan group (T n=12) were fed high-salt and telmisartan for 23u2005weeks too. Thirteen age-matched rats fed by normal-salt were used as controls (NS n=13). Myocardial morphology and structural changes were observed by HE staining and Masson staining. The content of superoxide dismutase (SOD) and malondialdehyde (MDA) in blood and left ventricle (LV) were measured by biochemistry and enzymology. Radioimmunoassay and enzyme linked immunosorbent assay (ELISA) were employed to determine the content of tumour necrosis factor-a (TNF-a) and C-reactive protein (CRP). The protein levels of nuclear factor-κb p65 (NF-κb p65) were evaluated by western blot. Results SBP in HSH was higher than other groups. In the high-salt groups, the ratio of left ventricular mass and body mass (LVMI), the myocardial cell diameter (CMD), the fibrosis area of myocardial interstitial (MIFI), the content of CRP, TNF-a (HSH (48.86±8.25), HSN (56.67±9.67) vs NS (40.89±4.37) ng/g, p<0.05), NF-κb p65 protein (HSH (87.77±10.3), HSN (75.18±16.67) vs NS (57.13±10.00), p<0.05) and SOD in the blood were significantly increased, while the level of SOD (HSH (58.34±5.78), HSN (54.59±6.65) vs NS (68.14±9.98) U/mgprot, p<0.05) in LV decreased. LVMI, CMD and MIFI were negatively correlated with SOD activity in LV respectively, and positively correlated with the protein levels of NF-κb p65. Telmisartan partly reversed myocardial remodelling decreased the protein levels of NF-κb p65 and TNF-a, and increased the SOD activity in LV. Conclusions The myocardial remodelling caused by high salt diet may be related to decreased SOD activity and inflammatory mechanism. Telmisartan prevents the salt-induced myocardial remodelling at least in part through inhibiting oxidative stress and inflammation.

THE EFFECTS OF LONG-TERM HIGH-SALT DIET ON BLOOD PRESSURE AND KIDNEY IN WISTAR RATS AND THE INTERVENTION OF TELMISARTAN

Objectives To investigate the effects of long-term high-salt diet on blood pressure and kidney and the intervention of telmisartan. Methods Wistar rats were randomly divided into three groups: Control group (NS group: given 0.5% NaCl), High-salt group (given 8% NaCl), and Intervention group (GY group: given 8% NaCl+telmisartan). Systolic blood pressure was assessed by the tail-cuff artery pressure. The urine was collected to measure the concentration of Na+, K+, microalbumin, total protein, and creatinine. At 24u2005weeks, the renal hypertrophy index was calculated. HE, Masson staining were used to observe the kidney morphology. Results Compared with NS group, systolic blood pressure was significantly increased and continued until the end of the experiment in one part of rats fed high-salt diet, whereas the other part of rats fed high-salt diet developed transient increase in blood pressure only from 8u2005weeks to 10u2005weeks of the experiment. So high-salt group rats were finally divided into High-salt hypertension group (HH group) and High-salt normal blood pressure group (HN group). In high-salt group rats, the renal hypertrophy index, microalbumin, total protein, and the ratio of Na+/K+ were increased p<0.01), creatinine clearance rate was decreased p<0.01), but the real damage in HN group was lighter than that in HH group. In GY group, systolic blood pressure was decreased, and the content of microalbumin, and total protein was reduced p<0.01), renal damage was ameliorated, but the renal hypertrophy index, creatinine clearance, and the ratio of Na+/K+ did not change (p>0.05). Conclusions Long-term high-salt diet may induce high blood pressure in part of the Wistar rats and cause renal damage independent of high blood pressure. Telmisartan can prevent high blood pressure and renal damage induced by high-salt diet in Wistar rats.

e0037 Effects of enalapril and irbesartan on aorta remodelling and ion pumps in renovascular hypertensive rats

Objective To investigate the effects of single-drug or combination therapy of enalapril and irbesartan on aorta remodelling and its mechanisms. Methods Renovascular hypertensive rats (RHD) induced by two-kidney one-clip method were treated with normal saline (model group, n=6), enalapril [10u2005mg/ (kg d), n=6], irbesartan [50u2005mg/ (kg·d), n=6] and enalapril+irbesartan [5u2005mg/ (kg d)+25u2005mg/ (kg d), n=6] for 6u2005weeks. Six sham-operated rats were used as controls. Aortic morphology and structural changes in the media were observed by HE staining, immunohistochemistry and Masson staining. The content of Angiotensin II (Ang II) was measured by radioimmunoassay. The activities and mRNA levels of Na+ pump and Ca2+ pump in aortic media were determined by enzyme assay and real-time PCR respectively. Results The media area of aorta and the Ang II content were significantly increased in model group, while the activities and the mRNA levels of Na+ pump and Ca2+ pump in aortic media were obviously decreased, and Na+ pump and Ca2+ activities were increased in enalapril group and irbesartan group (p<0.01). The Ang II content was obviously decreased in enalapril group, while increased in irbesartan group (p<0.01). The mRNA levels of sodium pump a1-subunit and plasma membrane calcium pump isoform 1 (PMCA1) in aorta smooth muscle tissue were significantly increased in enalapril group (p<0.01). The amelioration of blood pressure, Na+ pump and Ca2+ pump activities, media area and thickness in combination group was significantly better than single-drug intervened group (p<0.01). Conclusion The amelioration of aorta remodelling induced by enalapril and irbesartan may be associated with the increase of Na+ pump and Ca2+ pump activities. There may be some synergistic effects on ameliorating of Na+ pump and Ca2+ pump activities and aorta remodelling from combination of the two drugs. The effect of enalapril on Na+ pump and Ca2+ pump activities may be mediated by increasing their mRNA expression.

e0340 Actions of Irbesartan on ATPase activity and angiotensin ii in blood vessels from renal hypertensive rats

Objective To explore the effects of irbesartan on activities of Na+-K+-ATPase, Ca2+-ATPase, Angiotensin II (AngII) and vascular remodelling in renal hypertensive rats (RHRs). Methods Renovascular hypertension was induced by two kidney-one clip method. Eighteen RHRs were randomly divided into 3 groups: RHR model group (n=6), irbesartan treated group [50 mg/(kg d), n=6], withdrawal group (n=6). Six rats were included in sham operation group. Blood pressure was measured before and after using irbesartan. Thicknesses of vascular wall (TVW) of thoracic aorta and mesenteric artery were measured after 8u2005weeks. ATPase activities were determined by enzymatic colorimetric method. AngII level was detected by radioimmunoassay. Results Compared to the sham operation group, blood pressure, TVW, AngII levels of plasma and blood vessels were increased in RHR. The activities of Na+-K+-ATPase and Ca2+-ATPase were decreased in RHR. Blood pressure and the TVW of mesenteric artery were significantly decreased by irbesartan treatment. An increased AngII level and activity of Ca2+-ATPase in thoracic aorta and mesenteric artery were also found [thoracic aorta: (11.9±1.9) vs (7.5±1.6)u2005μmol Pi/(h·mg pro); mesenteric artery: (11.6±1.9) vs (8.2±0.8)u2005μmol Pi/(h·mg pro), both p<0.01]. No change of Na+-K+-ATPase activity was found after irbesartan treatment. After one-week discontinuation of treatment, blood pressure was significantly elevated, the activity of Ca2+-ATPase of thoracic aorta [(7.6±1.4)u2005μmol Pi/(h·mg pro)] and mesenteric artery [(6.9±1.3)u2005μmol Pi/(h·mg pro)] was decreased (both p<0.01). There was a significant negative correlation between AngII and the activity of Ca2+-ATPase in RHR. Conclusions The vascular remodelling of RHR may be associated with decreased vascular ATPases activities. Irbesartan can reverse vascular remodelling partially by increasing Ca2+-ATPase activity.