Ha T Y, Otsuka M, Arakawa N
Department of Food and Nutrition, Ochanomizu University, Tokyo, Japan.
J Nutr Sci Vitaminol (Tokyo). 1991 Aug;37(4):371-8. doi: 10.3177/jnsv.37.371.
The effect of ascorbate (AsA) on the synthesis of carnitine from gamma-butyrobetaine (BB) in primary cultured guinea pig hepatocytes was investigated. The hepatocyte monolayers preloaded with AsA were incubated for 4 h in medium with various concentrations of BB as the precursor of carnitine. The accumulation of carnitine reached a maximum when the cells were incubated with 0.05-1.0 mM BB and significantly decreased with excess BB (5 mM). In contrast, increasing concentrations of AsA supplemented to medium led to an increase in carnitine content, but AsA and total AsA contents in cells decreased by BB supplementation. Regarding the enhancement of hydroxylation of BB in the hepatocytes, AsA was the most effective among such other reducing agents as glutathione and dithiothreitol. Although erythorbate (ErA) also stimulated the hydroxylation of BB, carnitine content in cells preloaded with ErA was only 60% of that with AsA. These results suggest that AsA is specifically required for the hydroxylation of BB. Furthermore, AsA can regulate carnitine synthesis in the primary cultured guinea pig hepatocytes.
研究了抗坏血酸盐（AsA）对原代培养的豚鼠肝细胞中γ-丁酸甜菜碱（BB）合成肉碱的影响。预先加载AsA的肝细胞单层在含有不同浓度BB（作为肉碱前体）的培养基中孵育4小时。当细胞与0.05 - 1.0 mM BB孵育时，肉碱积累达到最大值，而当BB过量（5 mM）时显著降低。相反，向培养基中添加浓度增加的AsA会导致肉碱含量增加，但添加BB会使细胞中的AsA和总AsA含量降低。关于肝细胞中BB羟基化的增强，在谷胱甘肽和二硫苏糖醇等其他还原剂中，AsA是最有效的。虽然异抗坏血酸盐（ErA）也刺激BB的羟基化，但预先加载ErA的细胞中的肉碱含量仅为AsA的60%。这些结果表明，BB的羟基化特别需要AsA。此外，AsA可以调节原代培养的豚鼠肝细胞中的肉碱合成。
