Kettunen H, Peuranen S, Tiihonen K, Saarinen M
Danisco Cultor Innovation, Technology Center, Kantvik, Sokeritehtaantie 20, Fin-02460, Kantvik, Finland.
Comp Biochem Physiol A Mol Integr Physiol. 2001 Feb;128(2):269-78. doi: 10.1016/s1095-6433(00)00301-9.
The efficiency of betaine absorption into small intestinal slices of broiler chicks was studied in vitro with 14C-labeled betaine. The relative proportion of Na+-coupled betaine uptake, as well as the total uptake capacity was larger in the duodenum than in the jejunum. Dietary betaine increased the Na+-coupled uptake in the duodenum. In in vivo-experiments, methyl-14C-labeled betaine, methionine, or choline was fed to broiler chicks. Betaine appeared in the blood more rapidly, and reached a higher total concentration than choline or methionine. The data suggest that choline and methionine were associated with plasma lipoproteins whereas betaine remained free in the plasma. The label distribution in liver, kidney, and intestinal tissues was studied 24 h after label ingestion. Most of the label from betaine was found in the aquaeous phase in the muscle, while in the liver and jejunum the label from betaine was distributed more evenly between the aquaeous, lipid, and protein phases. Label from choline accumulated in the lipid fraction, particularly so in the liver, whereas label from methionine showed a more variable distribution pattern. The distribution results are interpreted in terms of specific roles of betaine, choline, and methionine in methyl group metabolism.
利用14C标记的甜菜碱在体外研究了肉仔鸡小肠切片对甜菜碱的吸收效率。十二指肠中Na+偶联的甜菜碱摄取相对比例以及总摄取能力比空肠中的更大。日粮中的甜菜碱增加了十二指肠中Na+偶联的摄取。在体内实验中，给肉仔鸡饲喂甲基-14C标记的甜菜碱、蛋氨酸或胆碱。甜菜碱在血液中出现得更快，并且总浓度比胆碱或蛋氨酸更高。数据表明，胆碱和蛋氨酸与血浆脂蛋白有关，而甜菜碱在血浆中保持游离状态。在摄入标记物24小时后研究了肝脏、肾脏和肠道组织中的标记物分布。甜菜碱的大部分标记物存在于肌肉的水相中，而在肝脏和空肠中，甜菜碱的标记物在水相、脂质相和蛋白质相之间分布得更为均匀。胆碱的标记物在脂质部分积累，尤其是在肝脏中，而蛋氨酸的标记物显示出更可变的分布模式。根据甜菜碱、胆碱和蛋氨酸在甲基代谢中的特定作用对分布结果进行了解释。
