Diez N, Barber A, Ponz F
Departamento de Fisiología y Nutrición, Facultad de Farmacia, Universidad de Navarra, Pamplona, Spain.
Rev Esp Fisiol. 1991 Jun;47(2):69-73.
The effect of the non-penetrating reagent of -SH groups: acid 5,5'-dithiobis (2-nitrobenzoic), (DTNB), on 1 mM galactose absorption in rat intestine in vivo has been studied. DTNB inhibits sugar absorption in about 35%, which is due to an action on the mediated transport component, but without affecting the diffusional passive one. Consequently it does not modify galactose absorption in the presence of 0.5 mM phlorizin or that of the non-transportable sugar 2-deoxy-glucose. Galactose transport inhibition appears after a not longer than 5 min preexposure period and it remains constant at least up to 30 min. The inhibitory effect does not vary between 0.1 and 1 mM DTNB and it reverses completely with 0.5 mM dithioerythritol. Protection by excess of substrate has not been observed. Results show that DTNB affects sulfhydryl groups very probably located at the luminal side and related to the proteins of the cotransport system.
巯基非穿透性试剂——5,5'-二硫代双(2-硝基苯甲酸)(DTNB)对大鼠体内肠道1 mM半乳糖吸收的影响已得到研究。DTNB抑制约35%的糖吸收，这是由于其对介导转运成分的作用，但不影响扩散性被动转运成分。因此，在存在0.5 mM根皮苷或不可转运糖2-脱氧葡萄糖的情况下，它不会改变半乳糖的吸收。半乳糖转运抑制在不超过5分钟的预暴露期后出现，并且至少在30分钟内保持恒定。在0.1至1 mM DTNB之间，抑制作用没有变化，并且用0.5 mM二硫苏糖醇可使其完全逆转。未观察到过量底物的保护作用。结果表明，DTNB很可能影响位于管腔侧且与共转运系统蛋白质相关的巯基。
