仔猪小肠对二肽吸收特点的研究

本试验采用体外外翻肠囊的方法研究了等摩尔浓度的Ｌ 甘氨酸 Ｌ赖氨酸组成的二肽（Ｇｌｙ－Ｌｙｓ）和游离甘氨酸和赖氨酸混合物（Ｇｌｙ＋Ｌｙｓ）在仔猪小肠各段的吸收特点。将仔猪小肠划分为空肠前段、中段、后段和回肠段，分别在各段设置了两个不同的培养液处理组，分别是浓度为２０ｍｍｏｌ／Ｌ的Ｇｌｙ－Ｌｙｓ和Ｇｌｙ＋Ｌｙｓ混合物培养液组。每个处理３个重复（回肠段无重复），每个重复为一个外翻肠囊，将每个外翻肠囊置１０ｍｌ培养液中培养１５分钟。旨在比较：体外培养１５分钟后，同一浓度下的Ｇｌｙ－Ｌｙｓ和Ｇｌｙ＋Ｌｙｓ在外翻肠囊各部位的吸收差别，从而确定Ｇｌｙ－Ｌｙｓ在仔猪各肠段的吸收特点。结果表明，同等摩尔浓度下，Ｇｌｙ－Ｌｙｓ组中的赖氨酸和甘氨酸在仔猪空肠中段肠组织的累积量显著大于Ｇｌｙ＋Ｌｙｓ组；从肠囊在１５分钟培养后总的氨基酸摄入量上看，Ｇｌｙ－Ｌｙｓ组的赖氨酸和甘氨酸在空肠中段高于Ｇｌｙ＋Ｌｙｓ组，且二者在赖氨酸上的差异显著。这说明，二肽中甘氨酸和赖氨酸至少在空肠中段的运输系统有别于游离态的甘氨酸和赖氨酸，且对二肽的运输显得比对游离氨基酸的运载更有效。

Study on the Characteristics of Dipeptide Absorption in Small Intestine of Piglets

Everted intestinal sac preparations were utilized in an in vitro experiment to determine the absorption characteristics of dipeptides and free amino acids and to compare the absorption of dipeptide and free amino acids mixtures at different levels of the small intestine. The small intestine was separated into four segments:proximal jejunum, middle jejunum, distal jejunum and ileum. Everted sacs prepared from the various intestinal segments (proximal jejunum, middle jejunum, distal jejunum and ileum) were then transferred into one of two treatment solutions:Krebs solution plus 20 mmol/L glylys dipeptide;an equivalent molar mixture of free glycine and free lysine. Each sac from each segment of jejunum and ileum was immersed in 10 ml of each the three test solutions in a 50 ml tissue culture flask, one sac per flask. The sacs were incubated in a 37 shaking water bath (100 cycles per minute) for 15 minutes. The results showed that the concentration of lysine and glycine in the middle jejunal tissues was greater in the tissues incubated in the dipeptide solution than in the tissues incubated in the free amino acids. Total uptake of glycine and lysine by the middle jejunum was more rapid than from the free amino acids. These findings imply that the mid jejunal intestinal cells possess a trnsport system for dipeptides that differs from the transport system for the free amino acids, and that dipeptide absorption is more rapid and efficient than absorption of free amino acids.