镉中毒解毒机理的研究——硒化合物的预防和治疗作用初探

STUDY ON THE DETOXIFICATION OF CADMIUM THE EXPLORE OF THE EFFECT OF SELENIUM COMPOUNDS ON THE PREVENTION AND TREATMENT OF CADMIUM TOXICOSIS

对大鼠组织胞液(Cytosol)的体外试验结果表明:亚硒酸钠、硒酸钠及硒化钠以明显影响[^(109)Cd]标记的氯化镉在组织胞液中的分布。硒酸钠、亚硒酸钠有较强的封闭金属硫蛋白(MT)与镉结合部位、激活分子量较大的蛋白质,捕获胞液中[^(109)Cd]的作用,还可使已经和MT结合的[^(109)Cd]被剥离,随后,[^(109)Cd]转入分子量较大的蛋白质上;亚硒酸钠还可使[^(109)Cd]转入分子量为32000～35000的蛋白质上。硒化钠仅有较弱的剥离与MT结合的镉,使之转入分子量较大的蛋白质上,但几乎不能阻止镉与MT结合。镉与大、中分子量蛋白质结合力远较它与MT的结合力弱,因而以能有利于镉被排出体外。

Metallothionein (MT) was synthesized by adding zinc sulphate (50ppm) in drinking water of rats for successive four days. Animals were sacrified, and the livers, kidneys and brains were removed, homogenized, cytosols of tissures were obtained by ultracentr-ifuging the homogenate. (109Cd) labelled CdCl2 was added into liver cytosol, results showed that most of the isotope was bound on MT. The activities of isotope on MT were approximately 65.6% of total counts. Above cytosol was heated in boiling water bath for 5 minutes and centrifuged, the supernatant was removed, and added (109Cd) labelled CdCl2, the results showed that almost all isotope was bound on MT, a tiny amount of isotope was found in remanent larger molecular (MW>75,000) weight proteins. However, if sodium selenate, or selenite, or selenide was added into the supernatant, results showed that isotopes would be bound to larger molecular weight proteins or on the proteins with molecular weight of 32000-35000 daltons instead of bound to on MT. Results in several assays indicated that selenate, or selenite could strongly block the site of MT which can bind cadmium, and stimunate larger molecular weight proteins to capture isotope in solution, and strip (109Cd) from MT, to remove isotope to larger or medium molecular weight proteins, but selenide has a weakly to strip (109Cd) from MT, almost has no ability to prevent (109Cd) to bind on MT. The fact that isotope bound on larger or medium molecular weight proteins is more labile than on MT suggested that it might be useful for excreting Cd from body by administration of selenium compounds in diets.