Berkels R, Egink G, Marsen T A, Bartels H, Roesen R, Klaus W
Institute of Pharmacology, University of Cologne, Cologne, Germany.
Hypertension. 2001 Feb;37(2):240-5. doi: 10.1161/01.hyp.37.2.240.
Short-term treatment of the endothelium with dihydropyridine calcium antagonists resulted in an increased release in NO that is not due to a modulation of L-type calcium channels, because macrovascular endothelial cells do not express this channel. We investigated whether long-term (48 hours) treatment of porcine endothelial cell cultures with the dihydropyridine calcium antagonist nifedipine resulted in a similar enhanced NO liberation. Regarding to the underlying mechanism, we examined whether (1) nifedipine changed the mRNA and protein levels of the constitutive endothelial NO synthase (NOS) in endothelial cell cultures or (2) nifedipine exerts an NO protective effect via its antioxidative properties, as revealed in a cell culture model and with native endothelium from porcine coronary arteries. Nifedipine induced a significant time- and concentration-dependent increase (132+/-47%, 1 micromol/L, 40 minutes' incubation) in the basal NO liberation (oxyhemoglobin assay). This increased NO release was not due to elevated NOS (type III) mRNA (Northern blot analysis) and protein (Western blot analysis) levels. However, nifedipine (both short- and long-term treatment) significantly reduced the basal and glucose (20 and 30 mmol/L)-stimulated formation of reactive oxygen species (lucigenin assay) of endothelial cell cultures and native cells. We conclude that the calcium antagonist nifedipine enhances the bioavailability of endothelial NO without significantly altering the NOS (type III) mRNA and protein expression, possibly via an antioxidative protection. This increased NO availability may cause part of the vasodilation and might contribute to the antithrombotic, antiproliferative, and antiatherosclerotic effects of dihydropyridine calcium antagonists.
用二氢吡啶类钙拮抗剂对内皮进行短期处理会导致一氧化氮（NO）释放增加，这并非由于L型钙通道的调节，因为大血管内皮细胞不表达该通道。我们研究了用二氢吡啶类钙拮抗剂硝苯地平对猪内皮细胞培养物进行长期（48小时）处理是否会导致类似的NO释放增强。关于潜在机制，我们检查了：（1）硝苯地平是否改变了内皮细胞培养物中组成型内皮型一氧化氮合酶（NOS）的mRNA和蛋白质水平；或者（2）硝苯地平是否通过其抗氧化特性发挥NO保护作用，这在细胞培养模型和猪冠状动脉的天然内皮中已得到证实。硝苯地平在基础NO释放（氧合血红蛋白测定）中诱导了显著的时间和浓度依赖性增加（132±47%，1μmol/L，孵育40分钟）。这种NO释放增加并非由于NOS（III型）mRNA（Northern印迹分析）和蛋白质（Western印迹分析）水平升高。然而，硝苯地平（短期和长期处理）均显著降低了内皮细胞培养物和天然细胞的基础活性氧生成以及葡萄糖（20和30 mmol/L）刺激的活性氧生成（光泽精测定）。我们得出结论，钙拮抗剂硝苯地平可增强内皮NO的生物利用度，而不会显著改变NOS（III型）mRNA和蛋白质表达，可能是通过抗氧化保护作用。这种增加的NO可用性可能是血管舒张的部分原因，并且可能有助于二氢吡啶类钙拮抗剂的抗血栓、抗增殖和抗动脉粥样硬化作用。
