钠替代对体外培养的仓鼠空肠对二肽甘氨酰肌氨酸摄取的影响。

Effects of sodium replacement on uptake of the dipeptide glycylsarcosine by hamster jejunum in vitro.

作者信息

Burston D, Matthews D M

出版信息

Clin Sci (Lond). 1987 Jul;73(1):61-8. doi: 10.1042/cs0730061.

Abstract

We report observations on transport of the hydrolysis-resistant dipeptide glycylsarcosine by rings of everted hamster jejunum in vitro in the presence and absence of Na+, using several substituents for Na+: Li+, K+, Cs+, Tris, choline and mannitol. At most concentrations, mediated influx of glycylsarcosine was depressed by Li+, K+, Cs+ and Tris, though not abolished. At high concentrations, it was moderately increased by choline and mannitol. Under conditions in which the tissue could concentrate the peptide in the presence of Na+, uptake was greatly depressed by all the substituents and the ability to concentrate was abolished. The Kt of mediated influx was affected in different ways according to the substituent used. Kt was reduced by Li+ replacement of Na+ and increased by choline replacement. Vmax was greatly reduced by all metallic substituents but not by non-metallic substituents. Though the results cannot yet be satisfactorily interpreted, they suggest possible reasons for previous conflicting results and show that it is impossible to make the unqualified statement that transport of glycylsarcosine is 'Na+-dependent'. It is now doubtful whether transport of this peptide into the intestinal cells is by co-transport with Na+, and the whole matter of Na+-dependence of intestinal peptide transport is in question.

摘要

我们报告了在有和没有Na⁺存在的情况下，使用几种Na⁺替代物（Li⁺、K⁺、Cs⁺、Tris、胆碱和甘露醇），对体外外翻仓鼠空肠环转运抗水解二肽甘氨酰肌氨酸的观察结果。在大多数浓度下，Li⁺、K⁺、Cs⁺和Tris会抑制甘氨酰肌氨酸的介导性内流，尽管并未完全消除。在高浓度下，胆碱和甘露醇会使其适度增加。在组织能够在Na⁺存在的情况下浓缩该肽的条件下，所有替代物都会极大地抑制摄取，并且浓缩能力被消除。介导性内流的Kt根据所使用的替代物而受到不同方式的影响。用Li⁺替代Na⁺会降低Kt，而用胆碱替代会增加Kt。所有金属替代物都会极大地降低Vmax，但非金属替代物则不会。尽管这些结果尚未得到令人满意的解释，但它们为先前相互矛盾的结果提出了可能的原因，并表明不能无条件地说甘氨酰肌氨酸的转运是“Na⁺依赖性的”。现在怀疑该肽进入肠细胞的转运是否是通过与Na⁺共转运，并且肠肽转运的整个Na⁺依赖性问题都受到质疑。