醛固酮促进大鼠血管钙化的可能机制

The Role and Possible Mechanism of Aldosterone in the Vascular Calcification of Rats

目的:在大鼠血管钙化模型上,探讨醛固酮(aldosterone,Aldo)在血管钙化中的作用及其可能机制。方法:肌注维生素D3和灌胃尼古丁(VDN)诱导大鼠血管钙化,运用von Kossa染色、原子吸收测定钙含量、45Ca2+沉积及碱性磷酸酶(ALP)活性测定判断血管钙化程度,半定量RT-PCR方法测定骨桥蛋白(OPN)mRNA水平;放射免疫法测定血浆和血管组织血管紧张素Ⅱ(AngⅡ)和Aldo含量。结果:VDN处理组大鼠血管von Kossa染色见平滑肌细胞内和细胞间基质有大量棕黑色颗粒聚集;主动脉钙含量较对照组高5.8倍(P<0.01);血管组织45Ca2+聚积和ALP活性分别较对照组高3倍和2.5倍(P<0.01);血管OPN mRNA表达明显上调58%(P<0.01);AngⅡ和Aldo含量分别较对照组高58%和80%(P<0.01)。运用血管紧张素转换酶抑制剂(ACEI)和Aldo受体阻断剂可明显改善上述指标变化,与单纯VDN处理组大鼠相比较,VDN+captopril组主动脉钙含量、45Ca2+聚积及ALP活性分别较单纯钙化组低37%、59%和62%(均P<0.01)。而VDN+spironolactone组分别低32%、44%和60%(均P<0.01)。血管OPN mRNA水平亦较单纯钙化组低30%和29%(P<0.01)。结论:VDN诱导的血管钙化大鼠血管组织AngⅡ和Aldo生成增加,ACEI和Aldo受体阻断剂明显减轻血管钙化,提示Aldo促进血管钙化并参与钙化发生。

Objective To explore the effects and its possible mechanism of endogenous aldosterone(Aldo) on vascular calcification in the rats.Methods The rats with vascular calcification were induced by intramuscularly administering vitamin D3 and gastric perfusion of nicotine(VDN).The vascular calcification was confirmed by von Kossa staining,the calcium contents were determined by atomic absorption and 45Ca2+ accumulation and activity of alkaline phosphatase(ALP).The levels of osteopontin(OPN) mRNA was measured by semi-quantitative RT-PCR.The contents of Ang Ⅱ and Aldo in plasma and vascular tissue were determined by radioimmunoassay.Results In the rats of VDN treatment group,a large number of brown-black granules were found gathering in smooth muscle cells and intercellular matrix by vascular von Kossa staining,and the content of calcium in artery was 5.8-fold,accumulation of 45Ca2+ and the activity of ALP in artery were 3-and 2.5-fold than those in control group,respectively(all P<0.01).The expression of vascular osteopontin(OPN) mRNA in rats of VDN treatment group was significantly increased by 58%(P<0.01).The contents of AngⅡ and Aldo in vascular tissue in VDN group were 58% and 80% higher than the control group,respectively.The changes could be significantly improved by using angiotensin-converting enzyme inhibitor(ACEI) and Aldo receptor antagonist.The degree of vascular calcification reduced,aortic calcium content,45Ca2+ accumulation and ALP activity in VDN + captopril group were 37%,59% and 62% lower than those of VDN group,respectively(all P<0.01),but the three indexes in the VDN + spironolactone group were 32%,44% and 60% lower than those of VDN group,respectively(all P<0.01).The levels of vascular OPNmRNA were 30% and 29% lower than those of VDN group,respectively(all P<0.01).Conclusion The generation of Aldo can be increased by vascular calcification induced by VDN.ACEI and Aldo receptor antagonist can decrease vascular calcification,showing that Aldo can promote and participate in vascular calcification.