氨氯地平与依那普利联用对肾性高血压大鼠主动脉重塑的影响

目的观察氨氯地平单用及联用依那普利对肾血管性高血压大鼠(RHR)主动脉重塑及主动脉平滑肌细胞膜钠泵、钙泵活性和钠泵а1亚单位及细胞质膜钙泵亚型1(PMCA1)mRNA表达的影响,探讨氨氯地平单用及联用依那普利改善动脉重塑的可能机制。方法建立"两肾一夹(2K1C)"肾性高血压大鼠模型,设立假手术组、模型组、氨氯地平组[5 mg/(kg.d)]、依那普利组[10 mg/(kg.d)]、氨氯地平+依那普利组[2.5 mg/(kg.d)+5 mg/(kg.d)],每组6只,药物连续干预6周。采用HE染色、免疫组织化学染色、Masson染色法检测主动脉中膜形态及结构变化并测量中膜厚度与腔径比(ML/LD)、中膜面积与管腔面积比(MA/LA),放射免疫法检测血管紧张素Ⅱ(AngⅡ)含量,酶学比色法检测细胞膜钠泵及钙泵活性,实时PCR法检测钠泵α1亚单位、PMCA1 mRNA表达水平。结果 RHR血压显著升高,主动脉ML/LD、MA/LA明显增加,中膜组织钠泵、钙泵活性及钠泵α1亚单位、PMCA1 mRNA表达水平明显降低(P<0.05或P<0.01)。氨氯地平及依那普利均能减小RHR主动脉ML/LD、MA/LA,改善平滑肌肥大和胶原沉积,且均能降低主动脉中膜AngⅡ水平并升高主动脉中膜钠泵、钙泵活性(均P<0.01)。氨氯地平可显著升高PMCA1 mRNA表达水平,依那普利上调钠泵α1亚单位、PMCA1 mRNA表达水平(均P<0.01)。氨氯地平及依那普利联合应用减小主动脉ML/LD、MA/LA,降低主动脉组织AngⅡ水平和升高钠泵、钙泵活性及PMCA1 mRNA表达水平存在协同作用(均P<0.01)。结论氨氯地平联用依那普利改善主动脉重塑优于两药单用,其机制可能与它们更有效阻断主动脉组织RAS,升高主动脉平滑肌细胞膜钠泵及钙泵活性有关。氨氯地平可能通过上调PMCA1 mRNA表达水平改善钙泵活性。

Effects of Amlodipine and Enalapril on Aorta Remodeling in Renovascular Hypertensive Rats

Aim To observe the effects of amlodipine only or with the enalapril on aorta remodeling and the activities of Na+ pump and Ca2+ pump,and the mRNA expressions of α1 subunit of Na+ pump and plasma membrane calcium pump isoform 1(PMCA1),and investigate the possible mechanisms of aorta remodeling attenuation by amlodipine and enalapril. Methods Renovascular hypertensive rat model was induced by two-kidney-one-clip method,and rats were consecutively treated with normal saline(model group),amlodipine [5 mg/(kg·d)],enalapril [10 mg/(kg·d)] and amlodipine +enalapril [2.5 mg/(kg·d)+ 5 mg/(kg·d)] for 6 weeks(n=6).Sham-operated rats were treated with normal saline as controls(n=6).Aortic morphology and structural changes in the aortic media,the ratio of media thickness/ luminal diameter(MT/ LD),and media area/ luminal area(MA/LA) were observed by HE staining,immunohistochemical staining and Masson staining.The content of angtension Ⅱ(AngⅡ) was measured by radioimmunoassay,the activity of Na+ pump and Ca2+ pump in aortic media were determined by enzyme colorimetry,and the mRNA expressions of α1 subunit of Na+ pump and PMCA1 were detected by Real-time PCR,respectively. Results In the model group,the ratio MT/ LD and MA/ LA of aorta and the AngⅡ content were significantly increased while the activities and the mRNA levels of Na+ pump and Ca2+ pump were obviously decreased(P<0.05~P<0.01).In the amlodipine group and the enalapril group,the blood pressure,the ratio MT/ LD and MA/ LA and the AngⅡ content were obviously decreased while the Na+ pump and Ca2+ pump activities were obviously increased(all P<0.01).In the amlodipine group,the mRNA level of PMCA1 was significantly increased.But in the enalapril group,the mRNA levels of both sodium pump a1-subunit and PMCA1 were obviously increased(all P<0.01).In combination group,the amelioration of the ratio MT/ LD and MA/ LA,ion pump activity and mRNA levels of PMCA1 were significantly greater than in single-drug intervened group(all P<0.01),and the AngⅡcontent also was decreased more greater than in single-drug intervened group(all P<0.01),and there were synergistic effects. Conclusions The combination of amlodipine and enalapril is better than single-drug therapy in the attenuation of aorta remodeling,and there may be some synergistic effects in inhibiting tissue RAS and increasing the activities of ion pumps.Ca2+ pump activity stimulated by amlodipine may be partially mediated through up-regulating PMCA1 mRNA.