Fate of soluble carbohydrate in the colon of rats and man.
Fate of soluble carbohydrate in the colon of rats and man.
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可溶性碳水化合物在大鼠和人结肠中的命运。
DOI：
10.1172/jci108383
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发表时间：
1976
期刊：
影响因子：
--
通讯作者：
M. Levitt
中科院分区：
文献类型：
--
作者：
J. Bond;M. Levitt
通过将14C标记的葡萄糖、乙酸盐和乳酸盐直接滴入盲肠后测量呼气14CO2和粪便14C，研究了葡萄糖在大鼠和人结肠中的命运。大鼠和人体分别给予400 mg和12.5 g [U-14C]-葡萄糖后6 h，盲肠内14CO2排泄与胃内滴注后一样快。当葡萄糖从粪便中回收时，不到20%的14C滴注到盲肠中，并且仅约15%的粪便14C为可透析形式。肠内给药葡萄糖转化为CO2取决于结肠植物群的存在，无菌大鼠给予[14 C]葡萄糖后14 CO2的最小排泄证明了这一点。相比之下，葡萄糖的发酵产物乙酸盐和乳酸盐在无菌大鼠中转化为CO2的速度与传统大鼠一样快。在结肠腔中的O2可用性的测量表明，不足的O2可用于葡萄糖的有氧代谢的结肠细菌。这些实验表明，结肠细菌厌氧代谢大部分葡萄糖为短链脂肪酸，其被宿主吸收和氧化。大多数剩余的粪便葡萄糖转化为具有有限渗透活性的较大分子形式。因此，结肠植物群通过减少未吸收碳水化合物的渗透负荷和通过使不能在小肠中吸收的碳水化合物的大百分比的卡路里的补救成为可能而有益于宿主。
The fate of glucose in the colon of rats and man was investigated by measuring breath 14CO2 and fecal 14C after direct instillation of 14C-labeled glucose, acetate, and lactate into the cecum. For the 6 h after administration of as much as 400 mg of [U-14C]-glucose to the rat and 12.5 g to man, 14CO2 excretion was as rapid after intracecal as after intragastric instillation. Less than 20% of 14C instilled into the cecum as glucose was recovered in feces and only about 15% of this fecal 14C was in a dialyzable form. The conversion of intracecally administered glucose to CO2 was dependent upon the presence of the colonic flora, as evidenced by the minimal excretion of 14CO2 after administration of [14C]glucose to germ-free rats. In contrast, acetate and lactate, fermentation products of glucose, were converted to CO2 as rapidly in germ-free rats as in their conventional counterparts. Measurement of O2 availability in the colonic lumen indicated that insufficient O2 was available for the aerobic metabolism of glucose by the colonic bacteria. These experiments suggest that the colon bacteria anaerobically metabolize most of the glucose to short-chain fatty acids, which are absorbed and oxidized by the host. Most of the remaining fecal glucose is converted to a larger molecular form that has limited osmotic activity. Thus, the colonic flora benefits the host by reducing the osmotic load of nonabsorbed carbohydrate and by making possible the salvage of a large percentage of the calories of carbohydrate, which is not absorbed in the small bowel.