Bloxam D L, Tan J C, Parkinson C E
Clin Chim Acta. 1984 Dec 29;144(2-3):81-93. doi: 10.1016/0009-8981(84)90041-x.
Using an ultrafiltration technique, apparent non-protein bound (NPB) zinc concentrations in plasma were found to be 2.2 +/- 0.2 (SEM) microgram Zn/l (10 observations) in normal males, 1.6 +/- 0.3 (10) micrograms/l in normal females and 1.2 +/- 0.2 (10) micrograms/l in pregnant mothers during their 16th week of gestation. These values are about 0.2% of the total plasma zinc concentrations, at least five-fold less than previous estimates. In amniotic fluid, the NPB-zinc concentration was 12.6 +/- 0.4 (10) micrograms/l, 5-10 times that of normal plasma, though the total zinc concentration (100 +/- 30 micrograms/l) was only one tenth that of plasma. When plasma or amniotic fluid samples were ultrafiltered without precaution against CO2 loss, their NPB-zinc concentrations increased, suggesting that pH changes alter zinc binding. The low concentration of NPB-zinc in plasma explains the low urinary excretion of zinc observed by others and would be expected to restrict the entry of zinc into cells.
采用超滤技术发现，正常男性血浆中表观非蛋白结合（NPB）锌浓度为2.2±0.2（标准误）微克锌/升（10次观察），正常女性为1.6±0.3（10）微克/升，妊娠第16周的孕妇为1.2±0.2（10）微克/升。这些值约占血浆总锌浓度的0.2%，比先前的估计值至少低五倍。在羊水中，NPB锌浓度为12.6±0.4（10）微克/升，是正常血浆的5至10倍，尽管总锌浓度（100±30微克/升）仅为血浆的十分之一。当血浆或羊水样本在未采取防止二氧化碳损失的预防措施下进行超滤时，其NPB锌浓度会增加，这表明pH值变化会改变锌的结合。血浆中NPB锌浓度较低解释了其他人观察到的锌尿排泄量低的现象，并且预计会限制锌进入细胞。
