| Objective:The aim of this study is to evaluate the pharmacodynamics of neotype endothelin-A receptor antagonist synthesized by Beijing institute of pharmacology and toxicology in pulmonary hypertension and right heart failure, and provides experimental evidence of new drug which possesses independent intellectual property right and novel chemical structure. Meanwhile, we investigate the mechanisms of effect of endothelin-A receptor antagonist in right heart failure.Methods:1,Pulmonary hypertension: Building pulmonary hypertension model in rats exposed in hypoxic chamber for 2 weeks; the integrative pharmacodynamics of compounds was evaluated by detecting pulmonary artery pressure, right ventricular hypertrophy index, heart rate, hematology, the content of ET-1 in plasma and lung and morphology of pulmonary vessel in hypoxic-induced rat pulmonary hypertension.2,The model of right heart failure: Building right heart failure model in rats through hypoxic- or MCT-induced; the effects of right heart function was observed in hypoxia rats by measuring right ventricular pressure, stroke volume, right ventricular hypertrophy index and hematology in order to select suitable method and optimal time to build model and evaluate the effect of anti-right heart failure.3,The preliminary research of mechanism of action was investigated the lung and heart of right heart failure rats induced by chronic hypoxia through detecting change of mRNA and protein synthesis and expression of ETR through real-time PCR and Western Blot, and then the results would be verified in primary culture of neonatal rat cardiomyocytes hypertrophy model induced by ET-1.Results:1,Pulmonary hypertension model induced by chronic hypoxia: After chronic hypoxia for two weeks, the data of SPAP,DPAP and MPAP in rats were increased 64.6%,34.6% and 51.9%, respectively. And the right ventricular hypertrophy index and the concentration of ET-1 in lung in rats were raised 58.3% and 75.3%, respectively. The results showed that the model of pulmonary hypertension in rats was successful.2,The effect of anti-pulmonary hypertension with YJ007: YJ007 is a new structural compounds and possess high selectional antagonistic effect on ETAR. In hypoxia-induced rat pulmonary hypertension models, pretreatment with YJ007 (10 mg/kg, 20 mg/kg, 40 mg/kg, administration twice/day, sc) can decrease pulmonary arterial pressure in dose-dependent manner. Especially, 40 mg/kg groups had significant difference on SPAP,DPAP and MPAP compared with model group (P<0.05), with the ratio of inhibition was 53.77%,35.44% and 48.71%, respectively. YJ007 (20 mg/kg and 40 mg/kg groups) can decrease the right ventricular hypertrophy index in model rats , and the inhibition rate of which 15.29% and 21.02%, respectively, but the results had no significant difference with model group. And the 40 mg/kg group of YJ007 can inhibit the concentration of ET-1 in lung of hypoxia-rats (P<0.05). Besides, YJ007 can prevent the remodeling of small pulmonary arteries, relieve the number of RBC and hemoglobin and increase the blood platelet number. But the dermat-toxicity of YJ007 in rats was severity.3,The right heart failure model induced by MCT: After subcutaneous injection of MCT in rats, there was loss of appetite, lassitude, epilation, difficulty breathing, and weight loss and so on during 4 w,5 w and 6 w. The systolic pressure in right ventricle increased 53.3% and 111.98% in model 4 w and 5 w groups compared with normal group, respectively; and the diastolic pressure increased 19.6% and 85.9%. But the extent of heart failure in model 6 weeks rats was serious and its mortality reached up to 80% proximately. The right ventricular hypertrophy index of rats in every model group raised 133.67%,62.24% and 174.83 (P<0.001), respectively. Overall, the model of right heart failure induced by MCT had many defects, for example, the hepatotoxicity of MCT and individual differences in rats.4,The right heart failure model induced by chronic hypoxia: After chronic hypoxia for 3 w,4 w and 5 w, there was loss of appetite, lassitude, epilation, difficulty breathing, and weight loss and so on. The data of SPAP in every hypoxia group were increased 44.2%,83.3% and 53.8% compared with normoxia group (P<0.05), respectively; and the DPAP and MPAP were increased 57.3%,94.2%,89.2% and 49.4%,87.6%,67.6%, compared with normoxia group (P<0.05), respectively. The stroke volume declined 59.84%,50.56 and 67.67% compared with normoxia group (P<0.01), and the right ventricular hypertrophy index increased 84%,112% and 108% (P<0.001). Besides, the number of RBC and hemoglobin increased and the number of platelet declined, the plasma concentration of BNP and the concentration of ET-1 in plasma and lung heightened. This method was suitable to evaluate the pharmacodynamics of new drug.5,The effect of anti-right heart failure with YJ009: YJ009, which belong to the same series compound with YJ007, superior to YJ007 on anti-pulmonary hypertension and inferior to YJ007 on dermat-toxicity, so YJ009 was selected to study the effect anti-right heart failure. Firstly, we ensure the 40 mg/kg group of YJ009 was the optimal dose through the research of anti-ET-1-induced increasing in carotid arteries blood pressure.In hypoxia-induced rat right heart failure models, pretreatment with YJ009 (40 mg/kg, administration twice/day, sc) can inhibit the SPAP,DPAP and MPAP of hypoxia rats, and the inhibition ratio was 72.58%,71.05% and 71.98%, respectively, compared with model group (P<0.05); and the YJ009 group also can decrease the right ventricular hypertrophy index in model rats , which the inhibition ratio is 26.42%, and reduce the number of RBC and hemoglobin and make the platelet add to the normal level (P<0.05). Besides, YJ009 can increase the stroke volume and decline the plasma concentration of BNP and the concentration of ET-1 in plasma and lung, but these results had no significant deviation compared with hypoxia solvent group, which the reason could be the large of individual difference and the small of sample size.6,The mechanism research of anti-right heart failure with YJ009: in real-time PCR, we found that the mRNA expression of ETAR increased significantly in hypoxia solvent group compared with normoxia solvent group, which the growth rate was 82.4% (P<0.05). YJ009 can inhibit the increased mRNA expression of ETAR induced by hypoxia and the inhibition rate was 41.6% (P<0.05). In western blot, the protein expression of ETAR in lung promoted significantly in hypoxia solvent group compared with normal, which the growth rate was 213.4% (P<0.001). And YJ009 cannot inhibit the increased protein expression of ETAR in lung induced by hypoxia. Besides, the protein expression of ETAR in heart promoted in hypoxia solvent group, and the protein expression of ETAR in YJ009 group was between normoxia and hypoxia solvent group. In primary culture of neonatal rat cardiomyocytes, ET-1(1 nM,10 nM,100 nM) can promote the protein of ETAR expression compared with the normal group, especially the group of ET-1 100nM (P<0.05). YJ009 can inhibit the protein of ETAR expression induced by ET-1, but it had no significant difference.Conclusion:1,YJ007 and YJ009, as the selective ETA receptor antagonist, belong to the same series compound. The inhibition ratio of pulmonary hypertension pressure and the right ventricular hypertrophy index with YJ007 was lower than with YJ009, but the dermat-toxicity of YJ007 was higher.2,through the comparison between MCT- and hypoxia-induced right heart failure in rats, we found that the model of right heart failure induced by MCT had significant hepatotoxicity and individual differences. While another model of right heart failure induced by hypoxia was easy and controlling.3,YJ009 can inhibit the pulmonary arterial pressure and the right ventricular hypertrophy index, increase the stroke volume and decrease the plasma concentration of BNP.4,In mechanism research, effects of YJ009 on anti-right heart failure maybe concern with the prevention of the protein expression of ETAR. |
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