巯基丙酸抑制大鼠远端结肠分离的顶端膜囊泡对丁酸的摄取。

Mercaptopropionate inhibits butyrate uptake in isolated apical membrane vesicles of the rat distal colon.

作者信息

Stein J, Schröder O, Milovic V, Caspary W F

机构信息

Second Department of Internal Medicine, Johann Wolfgang Goethe University, Frankfurt, Germany.

出版信息

Gastroenterology. 1995 Mar;108(3):673-9. doi: 10.1016/0016-5085(95)90438-7.

DOI:10.1016/0016-5085(95)90438-7

PMID:7875469

Abstract

BACKGROUND/AIMS: Previous observations have shown that mercapto- and bromo- short-chain fatty acids diminish fatty acid use in colonic epithelium. The aim of this study was to investigate whether this effect is attributable to the inhibition of short-chain fatty acid uptake.

METHODS

Apical membrane vesicles of rat colonocytes were prepared by a discontinuous sucrose gradient after isolation of membrane caps. [14C]butyrate uptake was measured by rapid filtration technique.

RESULTS

Preloading of isolated apical membrane vesicles with bicarbonate or butyrate stimulated [14C]butyrate uptake and resulted in up to fivefold overshoots. Increasing extravesicular butyrate concentrations saturated the bicarbonate-stimulated butyrate uptake with a binding constant of 44.7 +/- 5.9 mmol/L and a maximum velocity of 33.2 +/- 2.7 nmol.mg protein-1.3 s-1. Intravesicular butyrate uptake was inhibited by addition of 20 mmol/L 3-mercaptopropionate (43.0% +/- 5.6%), whereas 2-bromo-propionate (13.9% +/- 4.1%) and 4-bromobutyrate (22.6% +/- 5.3%) did not significantly alter butyrate uptake. Increasing concentrations of 3-mercaptopropionate had a competitive inhibitory effect on butyrate uptake with a binding constant following inhibition of 6.25 +/- 0.87 mmol/L and a maximum velocity of 5.82 +/- 1.01 nmol.mg protein-1.3 s-1.

CONCLUSIONS

Butyrate uptake in apical membrane vesicles of rat distal colon is mediated by a low-affinity anion transport system, which can be competitively inhibited by 3-mercaptopropionate but not by 2-bromopropionate and 4-bromobutyrate.

摘要

背景/目的：先前的观察表明，巯基和溴代短链脂肪酸会减少结肠上皮细胞中脂肪酸的利用。本研究的目的是调查这种效应是否归因于短链脂肪酸摄取的抑制。

方法

在分离膜帽后，通过不连续蔗糖梯度制备大鼠结肠上皮细胞的顶端膜囊泡。采用快速过滤技术测量[14C]丁酸的摄取。

结果

用碳酸氢盐或丁酸预加载分离的顶端膜囊泡可刺激[14C]丁酸的摄取，并导致高达五倍的过冲。增加囊泡外丁酸浓度可使碳酸氢盐刺激的丁酸摄取饱和，结合常数为44.7±5.9 mmol/L，最大速度为33.2±2.7 nmol·mg蛋白-1·3 s-1。加入20 mmol/L 3-巯基丙酸可抑制囊泡内丁酸的摄取（43.0%±5.6%），而2-溴丙酸（13.9%±4.1%）和4-溴丁酸（22.6%±5.3%）对丁酸摄取没有显著影响。增加3-巯基丙酸的浓度对丁酸摄取具有竞争性抑制作用，抑制后的结合常数为6.25±0.87 mmol/L，最大速度为5.82±1.01 nmol·mg蛋白-1·3 s-1。