HEPATIC ZINC IN METALLOTHIONEIN-NULL MICE FOLLOWING ZINC CHALLENGE - IN-VIVO AND IN-VITRO STUDIES
HEPATIC ZINC IN METALLOTHIONEIN-NULL MICE FOLLOWING ZINC CHALLENGE - IN-VIVO AND IN-VITRO STUDIES
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DOI：
10.1042/bj3090025
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发表时间：
1995-07-01
影响因子：
4.1
通讯作者：
ROFE, AM
中科院分区：
文献类型：
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作者：
COYLE, P;PHILCOX, JC;ROFE, AM
比较了新鲜分离和培养的对照(MT+/+)和金属硫蛋白(MT-/-)小鼠肝细胞对锌的摄取和蓄积。在新鲜分离的肝细胞中，锌-65的快速交换(10-15min)与培养液中的锌浓度成正比，在MT+/+和MT-/-小鼠的肝细胞中也发生同样程度的锌-65交换。在MT+/+和MT-/-肝细胞的24小时培养实验中，约40%的新获得的细胞相关锌附着在细胞表面，而不是内化。在MT+/+和MT-/-肝细胞培养中，内化锌(int锌)与胞外锌成正比增加。MT-/-肝细胞中的锌积累量仅为MT+/+细胞的60%，加入1mU M地塞米松(Dex)和重组小鼠白介素6(IL-6；100单位/ml)可使MT+/+肝细胞中MT的积累量增加8.6倍(50 mU M/+肝细胞)，并伴随着int锌的平行增加。地塞米松和IL-6不增加MT-/-肝细胞中的Int-Zn。注射锌5 mU/g后16h，MT-/-小鼠(n=10)血浆和尿锌浓度分别为69+/-10mU M和86+/-25mU M，MT+/+对照组(n=9)血浆和尿锌浓度分别为27+/-1mU M和23+/-4mU(P<0.001)。MT+/+组小鼠肝细胞内锌浓度增加一倍，MT-/-组显著增加15%。肝脏锌(干重)未见增加。结果表明，MT-/-小鼠体内锌的增加是由于肝脏失水所致，而不是由于锌的净摄取。似乎即使在极高的血浆锌浓度下，当没有MT可用于其封存时，也很少(如果有的话)在肝脏内积累。这一点在体外没有得到充分证明，这可能是由于细胞培养的本质，在细胞培养中，器官结构丢失，外部蛋白质结合环境不那么复杂。
Hepatic zinc uptake and accumulation were compared in freshly isolated and cultured hepatocytes prepared from control (MT + / +) and metallothionein (MT)-null (MT - / -) mice. In freshly isolated hepatocytes, rapid (10-15 min) exchange of Zn-65 was proportional to the Zn concentration in the medium and occurred to the same extent in hepatocytes from MT + / + and MT- / - mice. In 24h culture experiments with MT+ / + and MT - / - hepatocytes it was shown that approx. 40 % of newly acquired cell-associated Zn was attached to the cell surface and not internalized. In MT + / + and MT - / - hepatocyte cultures, internalized Zn (intZn) increased in proportion to extracellular Zn. Zn accumulation in MT-/- hepatocytes was only 60 % that of MT + / + cells, Addition of 1 mu M dexamethasone (Dex) and recombinant mouse interleukin-6 (IL-6; 100 units/ml) increased MT accumulation by 8.6-fold in MT + / + hepatocytes (at 50 mu M Zn) and there was an associated parallel increase in intZn. Dex and IL-6 did not increase intZn in the MT - / - hepatocytes. At 16 h after an intraperitoneal injection of 5 mu g/g Zn, plasma and urine Zn concentrations were 69 +/- 10 mu M and 86 +/- 25 mu M respectively in MT - / - mice(n = 10) and 27 +/- 1 mu M and 23 +/- 4 mu M respectively in MT + / + controls (n = 9) (P < 0.001, plasma; P < 0.05, urine). Hepatic cytosolic Zn concentrations doubled in MT + / + mice and increased by a significant 15% in MT - / - mice. There was no increase in hepatic Zn (dry wt.) concentrations or in total hepatic Zn, demonstrating that the increase in cytosolic Zn in MT - / - mice was due to hepatic water loss rather than net Zn uptake. It appears that even at extreme plasma concentrations of Zn, little if any accumulates within the liver when there is no MT available for its sequestration. That this is not fully demonstrated in vitro is probably due to nature of cell culture, where organ architecture is lost and the external protein binding milieu is less complex.