Stephens J R, Woolson R F, Cooke A R
Am J Physiol. 1976 Sep;231(3):848-53. doi: 10.1152/ajplegacy.1976.231.3.848.
The effect of three monosaccharides, three disaccharides, two dipeptides, combinations of tryptophan with two hexoses, one hexitol, and two amino acids ongastric emptying was studied in dogs to further define the samll intestinal receptors responsive to osmolytes and tryptophan. On a molar basis the disacchardies and dipeptides were almost twice as potent as their respective constituent monosaccharides or amino acids implying that the osmoreceptor is deep to the brush border disaccharidases and cytosol dipeptidases. Tryptophan probably acts by a mechanism different from the osmoreceptor since slowing of gastric emptying by tryptophan was inhibited by methionine which has no effect on a stimulant of the osmoreceptor mechanism. Lysine unlike methionine does not share the neutral amino acid transport pathway with tryptophan. Lysine did not change the inhibitory effect of tryptophan on gastric emptying. This imples that transport of tryptophan into the intestinal cell is necessary for its slowing effect. Glucose and galactose also inhibited the tryptophan effect whereas a nonabsorbed hexitor, mannitol, was without effect. Interference by the hexoses was also probably by competition with tryptophan for transport into the cell. These studies further indicate that the tryptophan receptor is different from the osmoreceptor.
研究了三种单糖、三种双糖、两种二肽、色氨酸与两种己糖、一种己糖醇及两种氨基酸的组合对犬胃排空的影响，以进一步明确小肠中对渗透溶质和色氨酸有反应的受体。以摩尔为基础，双糖和二肽的效力几乎是其各自组成单糖或氨基酸的两倍，这意味着渗透感受器位于刷状缘双糖酶和胞质二肽酶的深层。色氨酸的作用机制可能与渗透感受器不同，因为色氨酸引起的胃排空减慢受到蛋氨酸的抑制，而蛋氨酸对渗透感受器机制的刺激物没有影响。与蛋氨酸不同，赖氨酸不与色氨酸共享中性氨基酸转运途径。赖氨酸不会改变色氨酸对胃排空的抑制作用。这表明色氨酸进入肠细胞的转运对于其减慢作用是必要的。葡萄糖和半乳糖也会抑制色氨酸的作用，而一种不能被吸收的己糖醇——甘露醇则没有作用。己糖的干扰可能也是通过与色氨酸竞争进入细胞的转运。这些研究进一步表明，色氨酸受体与渗透感受器不同。
