Department of Animal Science, Texas A&M University, College Station, TX, 77843, USA.
Amino Acids. 2022 Jul;54(7):1025-1039. doi: 10.1007/s00726-022-03151-7. Epub 2022 Mar 16.
Enterocytes of young pigs are known to use glutamine, glutamate, and glucose as major metabolic fuels. However, little is known about the roles of aspartate, alanine, and fatty acids as energy sources for these cells. Therefore, this study simultaneously determined the oxidation of the amino acids and glucose as well as short- and long-chain fatty acids in enterocytes of developing pigs. Jejunal enterocytes were isolated from 0-, 7-, 14- and 21-day-old piglets, and incubated at 37 °C for 30 min in Krebs-Henseleit bicarbonate buffer (pH 7.4) containing 5 mM D-glucose and one of the following: D-[U-C]glucose, 0.5-5 mM L-[U-C]glutamate, 0.5-5 mM L-[U-C]glutamine, 0.5-5 mM L-[U-C]aspartate, 0.5-5 mM L-[U-C]alanine, 0.5-2 mM L-[U-C]palmitate, 0.5-5 mM [U-C]propionate, and 0.5-5 mM [1-C]butyrate. At the end of the incubation, CO produced from each C-labeled substrate was collected. Rates of oxidation of each substrate by enterocytes from all age groups of piglets increased (P < 0.05) gradually with increasing its extracellular concentrations. The rates of oxidation of glutamate, glutamine, aspartate, and glucose by enterocytes from 0- to 21-day-old pigs and of alanine from newborn pigs were much greater (P < 0.05) than those for the same concentrations of palmitate, propionate, and butyrate. Compared with 0-day-old pigs, the rates of oxidation of glutamate, aspartate, glutamine, alanine, and glucose by enterocytes from 21-day-old pigs decreased (P < 0.05) markedly, without changes in palmitate oxidation. Oxidation of alanine, propionate, butyrate and palmitate by enterocytes of pigs was limited during their postnatal growth. At each postnatal age, the oxidation of glutamate, glutamine, aspartate, and glucose produced much more ATP than alanine, propionate, butyrate and palmitate. The degradation of glutamate was initiated primarily by glutamate-pyruvate and glutamate-oxaloacetate transaminases. Our results indicated that amino acids (glutamate plus glutamine plus aspartate) are the major metabolic fuels in enterocytes of 0- to 21-day-old pigs.
已知仔猪的肠细胞将谷氨酰胺、谷氨酸和葡萄糖用作主要代谢燃料。然而，关于天冬氨酸、丙氨酸和脂肪酸作为这些细胞的能量来源的作用知之甚少。因此，本研究同时确定了发育中仔猪肠细胞中氨基酸和葡萄糖以及短链和长链脂肪酸的氧化。从 0、7、14 和 21 日龄仔猪中分离出空肠肠细胞，并在 37°C 下在含有 5mM D-葡萄糖和以下一种物质的 Krebs-Henseleit 碳酸氢盐缓冲液（pH 7.4）中孵育 30 分钟：D-[U-C]葡萄糖、0.5-5mM L-[U-C]谷氨酸、0.5-5mM L-[U-C]谷氨酰胺、0.5-5mM L-[U-C]天冬氨酸、0.5-5mM L-[U-C]丙氨酸、0.5-2mM L-[U-C]棕榈酸、0.5-5mM [U-C]丙酸和 0.5-5mM [1-C]丁酸。在孵育结束时，收集每个 C 标记的底物产生的 CO。所有年龄组仔猪肠细胞对每种底物的氧化速率均逐渐（P <0.05）随着其细胞外浓度的增加而增加。0-21 日龄仔猪肠细胞对谷氨酸、谷氨酰胺、天冬氨酸和葡萄糖以及新生仔猪丙氨酸的氧化速率（P <0.05）远高于相同浓度的棕榈酸、丙酸和丁酸。与 0 日龄仔猪相比，21 日龄仔猪肠细胞对谷氨酸、天冬氨酸、谷氨酰胺、丙氨酸和葡萄糖的氧化速率（P <0.05）明显下降，而棕榈酸的氧化速率没有变化。仔猪出生后生长过程中肠细胞对丙氨酸、丙酸、丁酸和棕榈酸的氧化有限。在每个新生后年龄，谷氨酸、谷氨酰胺、天冬氨酸和葡萄糖的氧化产生的 ATP 远远多于丙氨酸、丙酸、丁酸和棕榈酸。谷氨酸的降解主要由谷氨酸-丙酮酸和谷氨酸-草酰乙酸转氨酶启动。我们的结果表明，氨基酸（谷氨酸加谷氨酰胺加天冬氨酸）是 0-21 日龄仔猪肠细胞的主要代谢燃料。
