膳食补充 dl-蛋氨酸在猪离体空肠中强力诱导钠依赖性 l-蛋氨酸吸收。

Dietary Supplementation of dl-Methionine Potently Induces Sodium-Dependent l-Methionine Absorption in Porcine Jejunum Ex Vivo.

机构信息

Institute of Veterinary Physiology, Freie Universtität Berlin, Berlin, Germany.

Institute of Animal Nutrition, Freie Universtität Berlin, Berlin, Germany.

出版信息

J Nutr. 2020 Jul 1;150(7):1782-1789. doi: 10.1093/jn/nxaa115.

DOI:10.1093/jn/nxaa115

PMID:32359147

Abstract

BACKGROUND

Methionine is an essential amino acid (AA) with many fundamental roles. Humans often supplement l-Met, whereas dl-Met and dl-2-hydroxy-4-(methylthio)butanoic acid (dl-HMTBA) are more frequently used to supplement livestock.

OBJECTIVES

The study aimed to investigate whether dietary Met source alters the absorptive capacity for Met isomers in the small intestine of piglets.

METHODS

A total of 27 male 10-wk-old piglets in 3 feeding groups received a diet supplemented with 0.21% dl-Met, 0.21% l-Met, or 0.31% dl-HMTBA to meet the Met + cystine requirement. After ≥10 d, absorptive fluxes of d-Met or l-Met were measured at a physiological concentration of 50 μM and a high concentration of 5 mM in duodenum, middle jejunum, and ileum ex vivo. Data were compared by 2-factor ANOVA.

RESULTS

Across diets, fluxes of both Met isomers at both tested concentrations increased from duodenum to ileum by a factor of ∼2-5.5 (P < 0.05). Pigs supplemented with dl-Met had greater (P < 0.085) absorptive fluxes at 50 μM l-Met (0.50, 2.07, and 3.86 nmol · cm-2 · h-1) and d-Met (0.62, 1.41, and 1.19 nmol · cm-2 · h-1) than did pigs supplemented with dl-HMTBA (l-Met: 0.28, 0.76, and 1.08 nmol · cm-2 · h-1; d-Met: 0.34, 0.58, and 0.64 nmol · cm-2 · h-1) in duodenum, jejunum, and ileum, respectively. Only in jejunum of dl-Met-fed pigs, fluxes at 50 μM l-Met were reduced by the omission of luminal Na+ (from 3.27 to 0.86 nmol · cm-2 · h-1; P < 0.05) and by a cocktail of 22 luminal AAs (to 1.05 nmol · cm-2 · h-1; P < 0.05).

CONCLUSIONS

Dietary supplementation of dl-Met increases the efficiency of l-Met and d-Met absorption at physiologically relevant luminal Met concentrations along the small intestine of pigs, including a very prominent induction of an Na+-dependent transport system with preference for l-Met in the mid-jejunum. Dietary supplementation with dl-Met could be a promising tool to improve the absorption of Met and other AAs.

摘要

背景

蛋氨酸是一种必需氨基酸（AA），具有许多基本作用。人类通常补充 l-蛋氨酸，而 dl-蛋氨酸和 dl-2-羟基-4-（甲硫基）丁酸（dl-HMTBA）则更常被用于牲畜补充。

目的

本研究旨在探讨日粮蛋氨酸来源是否会改变仔猪小肠对蛋氨酸异构体的吸收能力。

方法

27 头 10 周龄雄性仔猪被分为 3 个饲养组，分别接受添加 0.21%dl-Met、0.21%l-Met 或 0.31%dl-HMTBA 的日粮，以满足蛋氨酸+胱氨酸的需求。在≥10d 后，在十二指肠、中段空肠和回肠离体条件下，以 50μM 的生理浓度和 5mM 的高浓度测量 d-Met 或 l-Met 的吸收通量。通过双因素方差分析比较数据。

结果

在所有日粮中，两种蛋氨酸异构体在两种测试浓度下的通量均从十二指肠增加到回肠，增加了约 2-5.5 倍（P<0.05）。与 dl-HMTBA 相比，补充 dl-Met 的仔猪在 50μM l-Met（0.50、2.07 和 3.86nmol·cm-2·h-1）和 d-Met（0.62、1.41 和 1.19nmol·cm-2·h-1）的吸收通量更高（P<0.085）。在十二指肠、空肠和回肠中，补充 dl-Met 的仔猪分别为 0.28、0.76 和 1.08nmol·cm-2·h-1；补充 dl-HMTBA 的仔猪分别为 0.34、0.58 和 0.64nmol·cm-2·h-1）。仅在 dl-Met 喂养的仔猪的空肠中，50μM l-Met 的吸收通量因腔内 Na+缺失（从 3.27 降至 0.86nmol·cm-2·h-1；P<0.05）和腔内 22 种必需氨基酸混合物（降至 1.05nmol·cm-2·h-1；P<0.05）而降低。