Effects Of Lacidipine On Proliferation And Collagen Synthesis Of Rat Cardiac Fibroblasts Induced By Vasopressin And Its Possible Signal Transduction Mechanism

Background It has been proved that the left ventricular hypertrophy is a strong independent risk factor for the morbidity and mortality of essential hypertension.The proliferation of cardiac fibroblasts and the hypertrophy of myocardial cell is the vital pathophysilological bases which lead to left ventricular hypertrophy.Hypertensive myocardial frbrosis has been shown to facilitate ventricular dysfunction, diminished cornary reserve and ventricular arrhythmias that adversely affect the clinical outcome of hypertensive patients.How to improve and reverse left ventricular myocardial frbrosis has become the focus in the treatment of essential hypertension.Lacidipine, a new long-acting dihydropyridine calcium antagonist, can decrease blood pressure and efficaciously protection target organ.It can significantly reduce the mortality of cardiovascular disease and cardiovascular events induced by hypertension.It si a important antihypertensive drugs which has great application prospects and long-term Furture.The result of clinical observation showed that, lacidipine has a certain therapeutic effect on reversing left ventricle hypertrophy of essential hypertension.But the role of lacidipine in the pathological cardiac hypertrophy has not been clearly defined.And whether lacidipine is effective in cardic interstitium is still obscure.Methods This study was therefore designed to observe the effects of lacidipine on cell proliferation and collagen synthesis of cultured CFs in Sprague-Dawley (SD) rats.Aim to study the possibility of attenuation effects of lacidipine on myocardial fibrosis and left ventricular hypertrophy.And investigate the role of ERK1/2 pathway in the modulation effects of lacidipine on myocardial fibrosis in order to elucidate the cellular and molecular mechanisms of cardiovascular protection effects of lacidipine.Furthermore, this study also want to investigate the effects of lacidipine on preventing myocarsium remodeling so as to provide a valuable theory and a novel pharmacological strategy for treatment of esstential hypertension and find a new way for application of lacidipine.Results (1) After treatment with 10-7mol/L AVP for 24h, the absorbance value(A490 Value) of MTT assay 0.232±0.013) was much higher than that of control group (0.132±0.008, P<0.01).The A490 values were decreased by co-intervention with 10-9 ~10 -6 mol/L lacidipine in a concentration dependent manner.They were 0.216±0.01,0.203±0.01,0.176±0.01和0.160±0.01 respectively, which were all significantly lower than that of AVP group (P<0.01), but higher than that of control group.Only treated with 10-7mol/L Lacidipine, the A490 value was 0.122±0.010, which was much lower than that of control group,and the differences had statistical significance(P<0.01). (2) The percentage of S stage and proliferation index (PI) in AVP group (13.06±0.83 and 21.70±1.55) were significantly increased compared with those of control group (4.60±0.60 and 8.97±1.56, P<0.01).In 10-7mol/L Lacidipine+10-7mol/L AVP group, the percentage of S stage and PI were 8.84±0.80 and 15.46±1.84, which were markedly lower than AVP group (P<0.01), but higher than control group.Only treated with 10-7mol/L Lacidipine, the percentage of S stage and PI (4.07±0.41 and 6.77±0.70) were much lower than control group (P<0.01). (3) In CFs stimulated by AVP, the mRNA espression level of typeⅠandⅢcollagen were 1.42±0.06 and 1.03±0.04, which were obviously higher than control group (1.01±0.05 and 0.73±0.04, P <0.01).In the presence of 10-7mol/L Lacidipine, the mRNA level of typeⅠa ndⅢcollagen were decreased markedly (1.19±0.0and 0.83±0.051, P <0.01), but still higher than control group(P<0.01).Only treated with 10-7mol/L Lacidipine, the mRNA levels (0.86±0.04 and 0.61±0.04) were much lower than control group (P<0.01).(4) mRNA levels of typeⅠandⅢcollagen were decreased by co-intervention with 10-9 ~10 -6 mol/L Lacidipine and 10 -7mol/L AVP in a concentration dependent manner.TypeⅠcollagen mRNA levels were 71.36±0.03,1.28±0.05,1.18±0.02 and 1.10±0.02 respectively.TypeⅢcollagen mRNA levels were 0.99±0.03,0.92±0.02,0.85±0.01 and 0.78±0.02 respectively.They were all significantly lower than that of AVP group(1.44±0.06和1.07±0.03 10-9 mol/L Lacidipine group P<0.05, 10 -8 ~10- 6mol/L Lacidipine group P<0.01).(5) The protein levels of typeⅠandⅢcollagen in AVP group (86.40±1.44 and 40.37±2.92 ng/mL) were significantly increased compared with those of control group(17.46±1.56 and 10.33±2.40 ng/mL, P<0.01).Protein levels were decreased by co-intervention with 10-9 ~10 -6 mol/L Lacidipine in a concentration dependent manner.TypeⅠcollagen protein levels were 76.97±2.91,58.02±2.81,40.71±3.88 and 29.05±2.93 ng/mL respectively.TypeⅢcollagen protein levels were 35.40±2.73,25.17±3.97,18.01±0.64 and 15.73±2.32 ng/mL respectively.They were all significantly lower than that of AVP group (for TypeⅠcollagen, 10-9 mol/L Lacidipine group P<0.05, 10 -9 ~10- 6mol/L Lacidipine group P<0.01; for TypeⅢcollagen, P<0.01 respectively), but still higher than those of control group (P<0.01).Only treated with 10-7mol/L Lacidipine, protein levels were 9.12±1.94 and 4.92±0.79 ng/mL, which were much lower than those of control group (P<0.01).(6) AVP increased the protein level of p-ERK1/2.In the AVP groups,the protein level of p-ERK1/2 were significantly higher than that of control group,while the protein level of t-ERK1/2 in all groups were not significantly different.As Lacidipine concentration rose, the protein level of p-ERK1/2 were significantly lower than that of AVP group(P<0.01),while the protein level of t-ERK1/2 in all groups were not significantly different(P>0.05).Conclusion (1) Lacidipine could inhibit the cell proliferation of cultured CFs induced by AVP in a concentration dependent manner.(2) Lacidipine had dramatic inhibition effects on mRNA and protein expressions of typeⅠandⅢcollagen of CFs induced by AVP in a concentration dependent manner.(3) AVP can induce the protein level of CFs p-ERK1/2.Lacidipine can inhibit the protein level of CFs p-ERK1/2 induced by AVP in a dose dependent manner, suggesting Lacidipine can inhibit proliferation and collagen synthesis induced by AVP and that probably realized via ERK1/2 phosphorylation.To conclude, Lacidipine could exert effects on reversal of myocardial fibrosis and myocardial hypertrophy through the inhibition of proliferation and collagen synthesis of CFs.The ERK signal pathway is involved in the mechanism of above-metioned processes.However, whether the ERK signal pathway is the only one signal transductive mechanism deserve further exploration.