Qiao Huan, Bell Jason, Juliao Saul, Li Liying, May James M
Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA.
J Vasc Res. 2009;46(1):15-24. doi: 10.1159/000135661. Epub 2008 May 31.
BACKGROUND/AIMS: Vascular smooth muscle cells contribute both to the structure and function of arteries, but are also involved in pathologic changes that accompany inflammatory diseases such as atherosclerosis. Since inflammation is associated with oxidant stress, we examined the uptake and cellular effects of the antioxidant vitamin ascorbic acid in cultured A10 vascular smooth muscle cells.
METHODS/RESULTS: A10 cells concentrated ascorbate against a gradient in a sodium-dependent manner, most likely on the sodium-dependent vitamin C transporter type 2 (SVCT2) ascorbate transporter, which was present in immunoblots of cell extracts. Although ascorbate did not affect A10 cell proliferation, it stimulated radiolabeled proline incorporation and type I collagen synthesis. The latter was evident in the cells as increases in proalpha1(I) collagen and conversion of proalpha1(I) and proalpha2(I) collagen to mature forms that were released from the cells and deposited as extracellular matrix. Intracellular type I procollagen maturation was optimal at intracellular ascorbate concentrations of 200 microM and below, which were readily achieved by culture of the cells at plasma physiologic ascorbate concentrations.
These results show that the SVCT2 facilitates ascorbate uptake by vascular smooth muscle cells, which in turn increases both the synthesis and maturation of type I collagen.
背景/目的：血管平滑肌细胞对动脉的结构和功能均有贡献，但也参与诸如动脉粥样硬化等炎症性疾病所伴随的病理变化。由于炎症与氧化应激相关，我们研究了抗氧化维生素抗坏血酸在培养的A10血管平滑肌细胞中的摄取及其细胞效应。
方法/结果：A10细胞以钠依赖的方式逆浓度梯度浓缩抗坏血酸，最有可能是通过细胞提取物免疫印迹中存在的钠依赖型2型维生素C转运体（SVCT2）抗坏血酸转运体。虽然抗坏血酸不影响A10细胞增殖，但它刺激了放射性标记的脯氨酸掺入和I型胶原合成。后者在细胞中表现为前α1（I）胶原增加以及前α1（I）和前α2（I）胶原转化为成熟形式，这些成熟形式从细胞中释放并沉积为细胞外基质。细胞内I型前胶原成熟在细胞内抗坏血酸浓度为200微摩尔及以下时最为理想，通过在血浆生理抗坏血酸浓度下培养细胞很容易达到这一浓度。
这些结果表明，SVCT2促进血管平滑肌细胞摄取抗坏血酸，进而增加I型胶原的合成和成熟。
