摘要
Short-chain fatty acid (SCFA) concentrations of intestinal contents from the herbivorous tilapia, Oreochromis mossambicus, were analysed by gas and high-performance liquid chromatography. Concentrations of acetate ranging from 3 to 18 mmol l-1 were found along the full length of the intestinal tract, as were trace amounts of propionate. Characteristics of [3H]acetate transport by the intestinal brush-border membrane were analysed in isolated brush-border membrane vesicles (BBMV). Influx of [3H]acetate into BBMV occurred by apparent anion exchange and was not enhanced by inwardly directed gradients of sodium or potassium, indicating the lack of sodium-dependent coupling for acetate transport. Competition and stimulation studies with various organic and inorganic anions revealed the likelihood of a transport system in which [3H]acetate is exchanged specifically for intracellular bicarbonate or other SCFA. Other anions tested had only limited or negligible effects on [3H]acetate uptake. Kinetic analysis over a concentration range of external acetate from 0.1 to 35 mmol l-1 yielded a carrier transport Km of 6.4 mmol l-1 and a Jmax of 5.3 nmol mg protein-1 10 s-1. Transport of [3H]acetate was not significantly affected by inhibitory drugs specific for anion exchangers. This study suggests that there is a specific antiport system for anions that is shared by bicarbonate and short-chain volatile fatty acids in the intestinal brush-border membrane of this herbivorous teleost.
摘要译文
通过气体和高性能液相色谱分析来自食草罗非鱼的肠内含量的短链脂肪酸（SCFA）肠肠溶液的浓度。沿着肠道的全长含有3至18mmol L-1的醋酸盐的浓度，如痕量的丙酸盐。肠刷边界乙酸膜囊泡（BBMV）分析了肠刷边膜的醋酸乙酸乙烯酯的特征。醋酸钠的[3H]乙酸盐的流入由明显的阴离子交换发生，并未通过向内定向的钠或钾的梯度增强，表明缺乏乙酸钠转运的钠依赖性偶联。具有各种有机和无机阴离子的竞争和刺激研究揭示了一种传输系统的可能性，其中[3H]乙酸酯专门为细胞内碳酸氢盐或其他SCA而交换。测试的其他阴离子仅对[3H]醋酸盐摄取的影响仅限或可忽略不计。在0.1至35mmol L-1的外部醋酸盐的浓度范围内的动力学分析产生了6.4mmol L-1的载流子，以及5.3nmol mg蛋白-10s-1的Jmax。乙酸盐的运输不会显着受阴离子交换剂特异性药物的显着影响。该研究表明，对于这种食草紧靠的肠道刷边膜中的碳酸氢盐和短链挥发性脂肪酸，存在特定的反毒性系统。
E. Titus. Short-chain fatty acid transport in the intestine of a herbivorous teleost[J]. Journal of Experimental Biology, 1988,135(1)