Boyd C A, Shennan D B
J Physiol. 1986 Oct;379:367-76. doi: 10.1113/jphysiol.1986.sp016258.
Inhibitors of SO4(2-) entry into and efflux from vesicles prepared from the brush border membrane of term human placenta have been studied, using 35SO4(2-) and an anion-exchange column assay. Divalent anions were found to be either potent or relatively feeble inhibitors of SO4(2-) uptake. Those which, like SO4(2-) itself, have a tetrahedral configuration, were strongly inhibitory and all of these anions were the metal oxides of elements of group VI (A and B) of the Periodic Table (chromate, molybdate, tungstate, selenate and thiosulphate). Divalent anions which were only weak inhibitors of SO4(2-) uptake were arsenate, phosphate and tetraborate. Chromate and to a lesser extent molybdate were effective inhibitors of SO4(2-) efflux from vesicles pre-loaded with SO4(2-). SO4(2-) efflux was insensitive to the electrical potential across the vesicle membrane. These results are discussed with respect to the mechanism for SO4(2-) transport across this membrane from mother to fetus and in the context of the transport to the feto-placental unit of the essential trace elements, selenium, chromium and molybdenum.
利用35SO4(2-)和阴离子交换柱分析法，对从足月人胎盘刷状缘膜制备的囊泡中SO4(2-)进入和流出的抑制剂进行了研究。发现二价阴离子对SO4(2-)摄取要么是强效抑制剂，要么是相对较弱的抑制剂。那些与SO4(2-)本身一样具有四面体构型的阴离子具有强烈的抑制作用，所有这些阴离子都是元素周期表中第VI族（A和B）元素的金属氧化物（铬酸盐、钼酸盐、钨酸盐、硒酸盐和硫代硫酸盐）。对SO4(2-)摄取仅有微弱抑制作用的二价阴离子是砷酸盐、磷酸盐和四硼酸盐。铬酸盐以及程度稍小的钼酸盐是预先装载了SO4(2-)的囊泡中SO4(2-)流出的有效抑制剂。SO4(2-)流出对囊泡膜两侧的电势不敏感。结合SO4(2-)从母体到胎儿跨此膜运输的机制以及必需微量元素硒、铬和钼向胎儿-胎盘单位运输的情况，对这些结果进行了讨论。
