Senn E, Scharrer E, Wolffram S
Institute of Veterinary Physiology, University of Zürich, Switzerland.
Biol Trace Elem Res. 1992 Apr-Jun;33:103-8. doi: 10.1007/BF02783998.
The influence of glutathione (1 mmol/L) (GSH) on in vitro mucosal uptake and in vivo absorption of 75Se-labeled selenite (10 mumol/L) was investigated in rat jejunum. For comparison, the effect of L-cysteine (1 mmol/L) on in vivo absorption of 75Se-labeled selenite was also studied. In the in vitro uptake experiments, only the mucosal surface was exposed to the incubation medium for 3 min. For the in vivo experiments, a luminal perfusion technique was employed. GSH inhibited in vitro mucosal Se uptake, whereas absorption in vivo was stimulated by GSH. L-Cysteine also stimulated in vivo Se absorption, confirming former in vitro mucosal uptake experiments. Thus, unlike L-cysteine, GSH affected in vitro and in vivo absorption of Se from selenite differently. Enzymatic cleavage of products of the reaction of selenite with GSH occurring more efficiently under in vivo than in vitro conditions may be a prerequisite for the stimulatory effect of GSH on Se absorption. This apparently does not apply to the stimulatory effect of cysteine. Since GSH occurs in the intestinal lumen under physiological conditions, it may contribute to the high bioavailability of Se from selenite.
在大鼠空肠中研究了谷胱甘肽（1毫摩尔/升）（GSH）对75硒标记亚硒酸盐（10微摩尔/升）体外黏膜摄取和体内吸收的影响。作为比较，还研究了L-半胱氨酸（1毫摩尔/升）对75硒标记亚硒酸盐体内吸收的影响。在体外摄取实验中，仅将黏膜表面暴露于孵育培养基中3分钟。在体内实验中，采用了肠腔灌注技术。GSH抑制体外黏膜对硒的摄取，而GSH刺激体内吸收。L-半胱氨酸也刺激体内硒吸收，证实了先前的体外黏膜摄取实验。因此，与L-半胱氨酸不同，GSH对亚硒酸盐中硒的体外和体内吸收有不同影响。亚硒酸盐与GSH反应产物的酶促裂解在体内条件下比体外条件下更有效地发生，这可能是GSH对硒吸收产生刺激作用的前提条件。这显然不适用于半胱氨酸的刺激作用。由于GSH在生理条件下存在于肠腔中，它可能有助于提高亚硒酸盐中硒的生物利用度。
