McCormick C C
J Nutr. 1984 Jan;114(1):191-203. doi: 10.1093/jn/114.1.191.
The present study was undertaken to compare apparent zinc metabolism in two organs, the liver and pancreas. Four-week-old chicks received an oral dose of saline or an equal volume of zinc solution containing 4, 8 or 16 mg zinc. The accumulation of zinc metallothionein (MT) was determined 24 hours postgavage in hepatic and pancreatic cytosol. The rate of MT synthesis was determined in both tissues by a pulse labeling technique. In response to orally administered zinc, plasma zinc increased sharply (by 3 hours) and in proportion to the amount of zinc given. At 12 hours there was little difference in plasma zinc. The concentration of zinc MT in pancreatic cytosol relative to liver was nearly fivefold higher in control chicks and increased at approximately twice the rate when chicks were given zinc. Despite this marked difference in both the rate and extent of zinc MT accumulation there was little evidence of a difference in the rate of MT synthesis. Quantitation of MT by anion-exchange chromatography demonstrated an apparent maximum in the rate of MT synthesis at 6 hours, which was apparently the same in pancreas and liver. Our data suggest that when compared to liver, the pancreas possesses a markedly higher concentration of MT-bound zinc and a greater propensity to accumulate zinc MT when zinc status is acutely elevated. This tissue difference appeared not to be due to a greater capacity to synthesize MT.
本研究旨在比较肝脏和胰腺这两个器官中锌的表观代谢情况。四周龄的雏鸡口服一剂生理盐水或等体积含4毫克、8毫克或16毫克锌的锌溶液。灌胃后24小时测定肝脏和胰腺细胞溶质中锌金属硫蛋白（MT）的蓄积量。通过脉冲标记技术测定两个组织中MT的合成速率。口服锌后，血浆锌急剧升高（3小时内），且与所给锌的量成比例。12小时时，血浆锌几乎没有差异。对照雏鸡胰腺细胞溶质中锌MT的浓度相对于肝脏高出近五倍，当雏鸡摄入锌时，其增加速率约为肝脏的两倍。尽管锌MT蓄积的速率和程度存在显著差异，但MT合成速率几乎没有差异的证据。通过阴离子交换色谱法对MT进行定量分析表明，MT合成速率在6小时时出现明显最大值，胰腺和肝脏中的情况显然相同。我们的数据表明，与肝脏相比，当锌状态急性升高时，胰腺中MT结合锌的浓度明显更高，且积累锌MT的倾向更大。这种组织差异似乎并非由于合成MT的能力更强。
