Mottaz P, Worbe J F
Reprod Nutr Dev (1980). 1980;20(4B):1331-8.
The influence of pH on the transfer of acetic, propionic and butyric acids was studied in vitro using everted sacs of the rat caecum. The sacs were filled with 2 ml of saline medium and then shaken 1 hr at 38 degrees C in flasks containing the same medium. A Krebs-Ringer phosphate incubation medium was used with O2 as gas phase. Incubation mediums containing 15 mM acetic, propionic and butyric acids were adjusted to give three different pH values: 7.91, 7.00 and 6.03. After incubation the mucosal and serosal fluids were collected and samples were taken to determine the pH and the volatile fatty acid concentrations. The pH values of mucosal and serosal fluids changed slightly during the course of the experiments. There was net volatile fatty acid influx into caecal tissue from the serosal medium and into the mucosal medium from the caecal tissue. Lowering the pH from 7.00 to 6.03 resulted in a significant decrease of serosal volatile fatty acid influxes. Caecal tissue retained more volatile fatty acids by lowering the pH from 7.91 to 7.00 and 6.03. Acetic acid accumulated in the caecal tissue against its electro-chemical gradient at pH 6.03. Two different mechanisms appeared to favor the transport of ionized and non-ionized forms of volatile fatty acids through the caecal membranes.
利用大鼠盲肠外翻囊在体外研究了pH对乙酸、丙酸和丁酸转运的影响。外翻囊充满2ml盐溶液培养基，然后在含有相同培养基的烧瓶中于38℃振荡1小时。使用Krebs-Ringer磷酸盐孵育培养基，以氧气作为气相。含有15mM乙酸、丙酸和丁酸的孵育培养基被调节至三种不同的pH值：7.91、7.00和6.03。孵育后，收集黏膜和浆膜液样本，测定其pH值和挥发性脂肪酸浓度。在实验过程中，黏膜和浆膜液的pH值略有变化。挥发性脂肪酸从浆膜培养基净流入盲肠组织，并从盲肠组织净流入黏膜培养基。将pH从7.00降至6.03导致浆膜挥发性脂肪酸流入量显著减少。通过将pH从7.91降至7.00和6.03，盲肠组织保留了更多的挥发性脂肪酸。在pH 6.03时，乙酸逆着其电化学梯度在盲肠组织中积累。两种不同的机制似乎有利于挥发性脂肪酸的离子化和非离子化形式通过盲肠膜进行转运。
