Rhoads J M, MacLeod R J, Hamilton J R
Pediatr Res. 1986 Sep;20(9):879-83. doi: 10.1203/00006450-198609000-00015.
We measured the response of jejunal sodium (Na) absorption to neutral amino acid (L-alanine) and to dipeptides (L-alanyl-L-alanine, glycylsarcosine) in normal piglets and in piglets with acute viral diarrhea after experimental infection with transmissible gastroenteritis (TGE) virus. In the TGE jejunum villi were blunted, crypts were deepened, and the epithelium was composed of relatively undifferentiated cells with reduced disaccharidase, decreased sodium-potassium-stimulated ATPase, and elevated thymidine kinase activities. The response of Na absorption to a maximal concentration of L-alanine (20 mM) or D-glucose (30 mM) was significantly blunted in TGE jejunum in Ussing chambers. However, the addition of L-alanine together with D-glucose caused a significantly greater increment of Na absorption than either L-alanine or D-glucose alone in control and TGE tissue. The effect of Na absorption of the dipeptide L-alanyl-L-alanine (10 mM), which was rapidly hydrolyzed by control and TGE mucosa, was similar to that of L-alanine (20 mM), while glycylsarcosine, a poorly hydrolyzed dipeptide, did not change net Na absorption in the jejunum. Our data support the concept of separate carrier systems for neutral amino acid and hexose in the crypt-type intestinal epithelium characterizing viral enteritis. We speculate that a sodium-cotransporting amino acid, if added to oral glucose-electrolyte solutions, could benefit oral rehydration therapy in acute viral diarrhea; neither of the dipeptides tested here can be expected to enhance absorption to any greater extent than its constituent amino acids.
我们测定了正常仔猪以及经传染性胃肠炎（TGE）病毒实验感染后患有急性病毒性腹泻的仔猪空肠对中性氨基酸（L-丙氨酸）和二肽（L-丙氨酰-L-丙氨酸、甘氨酰肌氨酸）的钠（Na）吸收反应。在TGE中，空肠绒毛变钝，隐窝加深，上皮由相对未分化的细胞组成，双糖酶减少，钠钾刺激的ATP酶降低，胸苷激酶活性升高。在Ussing chambers中，TGE空肠对最大浓度的L-丙氨酸（20 mM）或D-葡萄糖（30 mM）的Na吸收反应明显减弱。然而，在对照和TGE组织中，L-丙氨酸与D-葡萄糖一起添加导致的Na吸收增量明显大于单独的L-丙氨酸或D-葡萄糖。二肽L-丙氨酰-L-丙氨酸（10 mM）在对照和TGE黏膜中迅速水解，其对Na吸收的作用与L-丙氨酸（20 mM）相似，而甘氨酰肌氨酸是一种水解较差的二肽，对空肠净Na吸收没有影响。我们的数据支持在表征病毒性肠炎的隐窝型肠上皮中存在中性氨基酸和己糖的独立载体系统的概念。我们推测，如果将一种钠共转运氨基酸添加到口服葡萄糖电解质溶液中，可能会有益于急性病毒性腹泻的口服补液治疗；这里测试的两种二肽预期都不会比其组成氨基酸在更大程度上增强吸收。
