KINETIC-STUDIES ON THE METABOLISM OF SHORT-CHAIN FATTY-ACIDS AND GLUCOSE BY ISOLATED RAT COLONOCYTES
KINETIC-STUDIES ON THE METABOLISM OF SHORT-CHAIN FATTY-ACIDS AND GLUCOSE BY ISOLATED RAT COLONOCYTES
复制标题
DOI：
10.1016/0016-5085(94)90601-7
复制
发表时间：
1994-02-01
期刊：
影响因子：
29.4
通讯作者：
MORTENSEN, PB
中科院分区：
文献类型：
--
作者：
CLAUSEN, MR;MORTENSEN, PB
背景/目的：虽然在结肠粘膜代谢的短链脂肪酸的兴趣是稳步增加，动力学参数Vmax（最大速度）andKm（米氏常数）的这些酸完全氧化成CO2 by colonic epithelial cells have not previously been determined.Methods：分离的大鼠结肠细胞进行孵育的浓度范围of 14 C-标记的乙酸，丙酸，丁酸，和葡萄糖的存在下。氧化速率通过量化14 CO2的产生来获得。结果：乙酸、丙酸和丁酸的表观Vmax值相似（分别为1.114 ± 0.061、0.991 ± 0.072和1.007 ± 0.070 μmol/min · g），而葡萄糖的表观Vmax值显著低于乙酸（0.339 ± 0.022 μmol/min·g）。相应的Km值均不同，其大小顺序为丁酸（0.184 ± 0.017 mmol/ L）<丙酸（0.339 ± 0.025 mmol/L）<乙酸（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产生强烈的非竞争性抑制，对丙酸盐氧化产生混合型抑制。丙酸对乙酸的氧化是非竞争性抑制，对丁酸的氧化是竞争性抑制。乙酸盐仅轻微抑制丙酸盐和丁酸盐的氧化。结论：结肠上皮细胞似乎以丁酸盐>丙酸盐>乙酸盐的优先顺序利用短链脂肪酸。然而，如果丁酸盐的代谢受损或管腔供应有限，则丙酸盐或乙酸盐的氧化可提供细胞功能所需的能量。
Background/Aims:Although the interest in colonic mucosal metabolism of short-chain fatty acids is steadily increasing, the kinetic parameters Vmax(maximum velocity) andKm(Michaelis constant) of the complete oxidation of these acids into CO2by colonic epithelial cells have not previously been determined.Methods:Isolated rat colonocytes were incubated in the presence of a concentration range of14C-labeled acetate, propionate, butyrate, and glucose. Oxidation rates were obtained by quantifying the production of14CO2. VmaxandKmwere calculated by computer-fitting of the data to a Michaelis-Menten plot.Results:The apparent Vmaxvalues were similar comparing acetate, propionate, and butyrate (1.114 ± 0.061, 0.991 ± 0.072, and 1.007 ± 0.070 μmol/min · g, respectively), but significantly lower for glucose (0.339 ± 0.022 μmol/ min · g). The correspondingKmvalues 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.