Burk R F, Hill K E, Read R, Bellew T
Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee 37232.
Am J Physiol. 1991 Jul;261(1 Pt 1):E26-30. doi: 10.1152/ajpendo.1991.261.1.E26.
Selenoprotein P is a glycoprotein that contains greater than 60% of the selenium in rat plasma. Physiological experiments were undertaken to gain insight into selenoprotein P function. Selenium-deficient rats were injected with doses of selenium ranging from 25 to 200 micrograms/kg, and the appearance of selenoprotein P was compared with the appearance of glutathione peroxidase activity in plasma and in liver. Selenoprotein P concentration increased to 35% of control by 6 h, whereas glutathione peroxidase activity increased minimally or not at all. Moreover, in rats given 100 and 200 micrograms selenium/kg, selenoprotein P reached 75% of its concentration in control rats at 24 h, whereas glutathione peroxidase activity reached only 6% of control. Cycloheximide pretreatment blocked the appearance of selenoprotein P in response to selenium injection. Male and female rats had similar concentrations of selenoprotein P. Partially purified selenoprotein P and plasma glutathione peroxidase labeled with 75Se were administered intravenously to selenium-deficient and control rats. 75Se given as selenoprotein P disappeared more rapidly from plasma than did 75Se given as glutathione peroxidase. Selenium deficiency did not significantly affect 75Se disappearance from plasma. At 2 h, brain, but not other tissues, took up more 75Se in selenium-deficient rats than in control rats when 75Se was given as selenoprotein P. This suggests that brain has a specific uptake mechanism for selenium given in the form of selenoprotein P. These results demonstrate that several physiological properties distinguish selenoprotein P from glutathione peroxidase. However, they do not clearly indicate its function.
硒蛋白P是一种糖蛋白，在大鼠血浆中所含的硒超过60%。开展了生理学实验以深入了解硒蛋白P的功能。给缺硒大鼠注射25至200微克/千克剂量的硒，将血浆和肝脏中硒蛋白P的出现情况与谷胱甘肽过氧化物酶活性的出现情况进行比较。硒蛋白P浓度在6小时时增加至对照的35%，而谷胱甘肽过氧化物酶活性增加极少或根本没有增加。此外，在给予100和200微克硒/千克的大鼠中，硒蛋白P在24小时时达到对照大鼠浓度的75%，而谷胱甘肽过氧化物酶活性仅达到对照的6%。环己酰亚胺预处理可阻断注射硒后硒蛋白P的出现。雄性和雌性大鼠的硒蛋白P浓度相似。将部分纯化的硒蛋白P和用75Se标记的血浆谷胱甘肽过氧化物酶静脉注射给缺硒大鼠和对照大鼠。以硒蛋白P形式给予的75Se从血浆中消失的速度比以谷胱甘肽过氧化物酶形式给予时更快。缺硒对75Se从血浆中的消失没有显著影响。当以硒蛋白P形式给予75Se时，在2小时时，缺硒大鼠的脑比对照大鼠摄取了更多的75Se，但其他组织并非如此。这表明脑对以硒蛋白P形式给予的硒具有特定的摄取机制。这些结果表明，硒蛋白P在若干生理特性上与谷胱甘肽过氧化物酶不同。然而，它们并未明确表明其功能。
