Ascorbate uptake in pig coronary artery endothelial cells
Ascorbate uptake in pig coronary artery endothelial cells
复制标题
DOI：
10.1007/s11010-005-3442-0
复制
发表时间：
2005-03-01
影响因子：
4.3
通讯作者：
Grover, AK
中科院分区：
文献类型：
--
作者：
Best, KA;Holmes, ME;Grover, AK
尽管猪冠状动脉的平滑肌细胞和内皮细胞在形态和功能上是不同的，但抗坏血酸摄取仅在平滑肌细胞中表现出来。肾和肠上皮细胞中的抗坏血酸转运蛋白与平滑肌中的转运蛋白不同。我们用RT-PCR检测了猪冠状动脉内皮细胞中抗坏血酸转运和钠依赖性维生素C转运蛋白（SVCT）的mRNA表达。当C-14-抗坏血酸在内皮细胞中的摄取被检测为C-14或HPLC时，两者的值没有差异。c -14-抗坏血酸的摄取依赖于Na+，对l -抗坏血酸具有立体选择性，并被亚砜吡嗪抑制。对抗坏血酸的吸收动力学特征为K-m = 27 +/- 3 μ M (Hill系数= 1)，对Na+的吸收动力学特征为K-m = 73 +/- 14 mM （Hill系数= 2）。令人惊讶的是，内皮细胞具有与平滑肌细胞相似的动力学参数，只是内皮细胞的摄取速度略低。与平滑肌比较，两种组织类型均表达SVCT2 mRNA。内皮细胞与上皮细胞不同，上皮细胞主要表达SVCT1，但在这方面与平滑肌细胞相似。
Although smooth muscle and endothelial cells in pig coronary artery are morphologically and functionally distinct, ascorbate uptake has been characterized only in smooth muscle cells. Ascorbate transporters in kidney and intestinal epithelial cells differ from those in smooth muscle. We examined ascorbate transport and mRNA expression of sodium-dependent vitamin C transporters (SVCT) by RT-PCR in the pig coronary artery endothelial cell cultures. When C-14-ascorbate uptake in endothelial cells was examined as C-14 or by HPLC, the two values did not differ from each other. C-14-ascorbate uptake was Na+-dependent, stereoselective for L-ascorbate and inhibited by sulfinpyrazone. The kinetic characteristics of the uptake were: K-m = 27 +/- 3 mu M (Hill coefficient = 1) for ascorbate and K-m = 73 +/- 14 mM (Hill coefficient = 2) for Na+. Surprisingly, endothelial cells had similar kinetic parameters as smooth muscle cells, except for a slightly lower uptake velocity in endothelial cells. Comparison with the smooth muscle showed that both tissue types expressed mRNA for SVCT2. Endothelial cells differ from epithelial cells which express mainly SVCT1 but resemble smooth muscle cells in this respect.