近生理条件下红细胞对锌的摄取。

The uptake of zinc by erythrocytes under near-physiological conditions.

作者信息

De Kok J, Van Der Schoot C, Veldhuizen M, Wolterbeek H T

机构信息

Department of Radiochemistry, Delft University of Technology, The Netherlands.

出版信息

Biol Trace Elem Res. 1993 Jul;38(1):13-26. doi: 10.1007/BF02783978.

DOI:10.1007/BF02783978

PMID:7691128

Abstract

The in vitro uptake of zinc by erythrocytes was measured under near-physiological conditions, using 65Zn as a radioactive tracer. Because of the presence of serum albumin--a strong zinc ligand--a low concentration of medium free zinc was maintained. Under these conditions a high-affinity carrier for zinc transport over the cell membrane was identified. With human erythrocytes, a Michaelis constant (Km) of 0.2 nM with respect to free medium zinc was measured and a Vmax of 4.5 nmoles Zn transported per h/g dry wt. The Km for medium Zn increases when the size of the internal erythrocytic Zn pool is augmented, whereas Vmax remains virtually unchanged. A model to explain this phenomenon is proposed. It is suggested that this phenomenon could underlie observations, confirmed here, that the in vitro uptake of Zn by animal erythrocytes depends on the Zn status of the animal.

摘要

在接近生理条件下，以65Zn作为放射性示踪剂，测定红细胞对锌的体外摄取。由于存在血清白蛋白（一种强锌配体），培养基中游离锌的浓度保持在较低水平。在这些条件下，鉴定出一种用于锌跨细胞膜转运的高亲和力载体。对于人类红细胞，测得相对于游离培养基锌的米氏常数（Km）为0.2 nM，每小时每克干重转运锌的最大速度（Vmax）为4.5纳摩尔。当红细胞内锌池的大小增加时，培养基锌的Km增加，而Vmax实际上保持不变。提出了一个解释这一现象的模型。有人认为，这种现象可能是此处所证实的动物红细胞对锌的体外摄取取决于动物锌状态这一观察结果的基础。