Caveolae Depletion Contributes to Vasorelaxant Effects of Chenodeoxycholic Acid
Caveolae Depletion Contributes to Vasorelaxant Effects of Chenodeoxycholic Acid
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DOI：
10.1159/000478683
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发表时间：
2017-06
影响因子：
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通讯作者：
Zhongchao Wang;Q. Lv;Huan Liu;Yue Wu;Yun-gang Bai;Yaoping Cheng;Yuting Su;Yue Cai;Jinwen Yu-Jinw
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文献类型：
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作者：
Zhongchao Wang;Q. Lv;Huan Liu;Yue Wu;Yun-gang Bai;Yaoping Cheng;Yuting Su;Yue Cai;Jinwen Yu-Jinw
背景/目标：高浓度的胆汁酸（BA）诱导疏水性依赖性血管舒张效应，疏水性BA比亲水性BA表现出更大的反应，其潜在的机制尚不清楚。小窝是内皮细胞（EC）膜上的内陷结构，其捕获内皮型一氧化氮合酶（eNOS）以阻止其活化，eNOS在血管功能调节中起关键作用。本研究的目的是探讨小窝的作用在BA的血管舒张作用。方法：以鹅去氧胆酸（CDCA）和胆酸（CA）分别代表疏水性和亲水性BA。腹主动脉血管反应采用等长记录法。透射电镜观察细胞膜小窝的形态。Western blot检测总eNOS（t-eNOS）和磷酸化eNOS（p-eNOS）蛋白表达。荧光法测定一氧化氮（NO）含量。结果如下：我们证明，CDCA和甲基-β-环糊精（MCD）（一种常用的胆固醇清除剂）在内皮完整的腹主动脉中可引起血管收缩（P < 0.05），减少氯化钾（KCl）或苯丙氨酸（PE）引起的血管收缩（P <0.05），增强乙酰胆碱（Ach）引起的血管舒张（P < 0.05），但在内皮剥脱或CA处理的血管中则不然。CDCA和MCD可明显破坏腹主动脉内皮细胞的小囊结构，而CA则无此作用，胆固醇孵育可恢复此结构（P < 0.05）。CDCA和MCD处理的血管中t-eNOS蛋白表达显著低于对照组（P < 0.05），而p-eNOS蛋白表达和NO含量显著高于对照组（P < 0.05）。内皮剥脱或胆固醇补充可逆转该效应。此外，在胆固醇孵育下，CDCA、CA或溶媒处理血管的血管反应无显著差异。结论：这些结果表明，CDCA减少了腹主动脉EC上的小窝，促进eNOS磷酸化和NO产生，这有助于其血管舒张作用。
Background/Aims: High concentration of bile acids (BAs) induces hydrophobicity-dependent vasorelaxtant effects with hydrophobic BAs showing greater responses than hydrophilic BAs, of which the underlying mechanisms are still unclear. Caveolae are invaginations on membranes of endothelial cells (ECs) entraping endothelial nitric oxide synthase (eNOS) to prevent its activation, which plays a critical role in regulation of vascular function. The purpose of the present study was to investigate the role of caveolae in vasorelaxant effects of BAs. Methods: Chenodeoxycholic acid (CDCA) and cholic acid (CA) were used to represent hydrophobic and hydrophilic BA, respectively. Vascular responses of abdominal aorta were measured by isometric force recording. Morphology of caveolae was examined by transmission electron microscopy. Protein expression of total eNOS (t-eNOS) or phosphorylated eNOS (p-eNOS) was determined by Western blot. Nitric oxide (NO) content was observed by fluorometric assay. Results: We demonstrated that CDCA as well as Methyl-β-cyclodextrin (MCD), a commonly used reagent for cholesterol depletion, reduced potassium chloride (KCl)- or phenylephrine (PE)-elicited vasoconstriction (P < 0.05), and enhanced acetylcholine (Ach)-elicited vasodilatation (P < 0.05) in endothelium-intact abdominal aorta but not in endothelium-denuded or CA-treated vessels. CDCA and MCD, but not CA significantly disrupted caveolae structure on ECs of abdominal aorta which was recovered by cholesterol incubation (P < 0.05). Protein expression of t-eNOS was significantly decreased (P < 0.05), and that of p-eNOS together with NO content was significantly increased in CDCA- and MCD- but not CA-treated vessels (P < 0.05) as compared with vehicle. The effect was reversed by either endothelium-denudation or cholesterol replenishment. Moreover, with cholesterol incubation, no significant differences were found in vascular responses among CDCA-, CA- or vehicle-treated vessels. Conclusion: These results indicate that CDCA diminishes caveolae on ECs of abdominal aorta promoting eNOS phosphorylation and NO production which contributes to its vasorelaxtant effect.