大鼠离体结肠细胞对短链脂肪酸和葡萄糖代谢的动力学研究。

Kinetic studies on the metabolism of short-chain fatty acids and glucose by isolated rat colonocytes.

作者信息

Clausen M R, Mortensen P B

机构信息

Department of Medicine A, Rigshospitalet, University of Copenhagen, Denmark.

出版信息

Gastroenterology. 1994 Feb;106(2):423-32. doi: 10.1016/0016-5085(94)90601-7.

DOI:10.1016/0016-5085(94)90601-7

PMID:8299908

Abstract

BACKGROUND/AIMS: Although the interest in colonic mucosal metabolism of short-chain fatty acids is steadily increasing, the kinetic parameters Vmax (maximum velocity) and Km (Michaelis constant) of the complete oxidation of these acids into CO2 by colonic epithelial cells have not previously been determined.

METHODS

Isolated rat colonocytes were incubated in the presence of a concentration range of 14C-labeled acetate, propionate, butyrate, and glucose. Oxidation rates were obtained by quantifying the production of 14CO2. Vmax and Km were calculated by computer-fitting of the data to a Michaelis-Menten plot.

RESULTS

The apparent Vmax values were similar comparing acetate, propionate, and butyrate (1.114 +/- 0.061, 0.991 +/- 0.072, and 1.007 +/- 0.070 mumol/min.g, respectively), but significantly lower for glucose (0.339 +/- 0.022 mumol/min.g). The corresponding Km values were all different and in the order of butyrate (0.184 +/- 0.017 mmol/L) < propionate (0.339 +/- 0.025 mmol/L) < acetate (0.487 +/- 0.019 mmol/L) < glucose (0.777 +/- 0.051 mmol/L). In substrate competition experiments, butyrate caused a strong noncompetitive inhibition of acetate oxidation and a mixed type of inhibition of propionate oxidation. Propionate inhibited the oxidation of acetate noncompetitively and that of butyrate competitively. Acetate only slightly inhibited the oxidation of propionate and butyrate.

CONCLUSIONS

Colonic epithelial cells seem to utilize short-chain fatty acids in a preferential order of butyrate > propionate > acetate. Oxidation of propionate or acetate, however, may provide the energy needed for cellular functions if the metabolism of butyrate is impaired or the luminal supply is limited.

摘要

背景/目的：尽管对结肠黏膜中短链脂肪酸代谢的研究兴趣日益浓厚，但此前尚未测定结肠上皮细胞将这些酸完全氧化为二氧化碳的动力学参数Vmax（最大速度）和Km（米氏常数）。

方法

将分离的大鼠结肠细胞在一系列浓度的14C标记的乙酸盐、丙酸盐、丁酸盐和葡萄糖存在下进行孵育。通过定量14CO2的产生来获得氧化速率。通过将数据计算机拟合到米氏曲线来计算Vmax和Km。

结果

乙酸盐、丙酸盐和丁酸盐的表观Vmax值相似（分别为1.114±0.061、0.991±0.072和1.007±0.070 μmol/min·g），但葡萄糖的明显较低（0.339±0.022 μmol/min·g）。相应的Km值各不相同，顺序为丁酸盐（0.184±0.017 mmol/L）＜丙酸盐（0.339±0.025 mmol/L）＜乙酸盐（0.487±0.019 mmol/L）＜葡萄糖（0.777±0.051 mmol/L）。在底物竞争实验中，丁酸盐对乙酸盐氧化有强烈的非竞争性抑制作用，并对丙酸盐氧化有混合型抑制作用。丙酸盐对乙酸盐氧化有非竞争性抑制作用，对丁酸盐氧化有竞争性抑制作用。乙酸盐仅对丙酸盐和丁酸盐的氧化有轻微抑制作用。