依那普利、厄贝沙坦单用和联用对高血压大鼠主动脉重塑与中膜钠泵及钙泵的影响

Effects of Enalapril and Irbesartan Given Singly or Combined on Aorta Remodeling and Na^+ Pump and Ca^(2+) Pump in Renovascular Hypertensive Rats

目的观察依那普利、厄贝沙坦单用及联用改善肾血管性高血压大鼠(RHR)主动脉重塑的疗效,观察RHR主动脉平滑肌细胞膜钠泵、钙泵活性及钠泵α1亚单位、细胞质膜钙泵亚型1(PMCA1)mRNA表达水平变化,探讨依那普利及厄贝沙坦改善动脉重塑的可能机制。方法建立"两肾一夹"RHR模型,设立假手术组(n=6)、模型组(n=6)、依那普利组[10mg/(kg.d),n=6]、厄贝沙坦组[50mg/(kg.d),n=6]、依那普利+厄贝沙坦组[5mg/(kg.d)+25mg/(kg.d),n=6)],药物连续干预6周。采用HE染色、免疫组化染色、Masson染色观察主动脉中膜形态和结构变化,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,realtime PCR法检测细胞膜钠泵及钙泵mRNA表达水平。结果 RHR血压显著升高,主动脉中膜面积及厚度明显增加,组织局部钠泵、钙泵活性及钠泵α1亚单位、PMCA1 mRNA表达水平明显降低(P<0.01)。依那普利及厄贝沙坦均能减小RHR主动脉中膜面积及厚度,改善平滑肌肥大和胶原纤维含量增加,且均能升高RHR主动脉中膜钠泵、钙泵活性(P<0.01或P<0.05)。依那普利降低主动脉中膜AngⅡ含量,上调钠泵α1亚单位、PMCA1 mRNA表达水平(P<0.01),而厄贝沙坦升高动脉中膜AngⅡ含量(P<0.01),对钠泵α1亚单位、PMCA1 mRNA表达水平无显著影响。两药联合降压及减小动脉中膜面积、厚度和升高钠泵、钙泵活性存在协同作用(P<0.01)。结论依那普利、厄贝沙坦联用改善主动脉重塑优于两药单用,其机制可能与它们升高主动脉中膜钠泵和钙泵活性有关。依那普利可能通过上调钠泵及钙泵mRNA表达水平改善钠泵及钙泵活性受抑。

Objective To investigate the clinical efficacy of enalapril and irbesartan,singly or combined,for aorta remodeling and relevant mechanisms. Methods Twenty-four renovascular hypertensive rats （RHR）developed by ＂two-kidney and one-clip＂ method were treated consecutively with normal saline（model group,n=6）,enalapril [10 mg/（kg ·d）,n=6],irbesartan [50 mg/（kg ·d）,n=6] and enalapril＋irbesartan [5 mg/（kg ·d）＋25 mg/（kg ·d）,n=6] for 6 weeks. Six sham-operated rats were used as controls. Aortic morphology and structural changes in the media were observed by HE staining,immunohistochemical staining 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 colorimetry and real-time PCR respectively. Results In the model group,the media area of aorta and the Ang Ⅱ content were significantly increased while the activities and mRNA levels of Na＋pump and Ca2＋ pump in aortic media obviously decreased. In the enalapril group and irbesartan group,Na＋pump and Ca2＋ pump activities were increased,with Ang Ⅱ content obviously decreased in enalapril group but increased in irbesartan group（P〈0.01）. The mRNA levels of sodium pump α1-subunit and plasma membrane calcium pump isoform 1 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 were significantly greater than that in single-drug intervened group （P〈0.01）. Conclusion The amelioration of aorta remodeling induced by the combination of enalapril and irbesartan therapies may be associated with the increase of Na＋pump and Ca2＋ pump activities. There may be some synergistic effects on the amelioration of Na＋ pump and Ca2＋ pump activities and aorta remodeling from combination of the two drugs. Enalapril exerts its activating effects on inhibited Na＋ pump and Ca2＋ pump activities probably by increasing their mRNA expressions.