Intracellular zinc movement and its effect on the carbohydrate metabolism of isolated rat hepatocytes
Intracellular zinc movement and its effect on the carbohydrate metabolism of isolated rat hepatocytes
复制标题
DOI：
10.1074/jbc.271.4.1941
复制
发表时间：
1996-01-26
影响因子：
4.8
通讯作者：
Kleineke, J
中科院分区：
文献类型：
--
作者：
Brand, IA;Kleineke, J
本文研究了锌离子对喂饲大鼠肝细胞糖代谢和细胞内锌离子的影响。添加氯化锌使乳酸产量增加近3倍，净葡萄糖产量增加约50%。半最大速率出现在约40亩M的氯化锌上。当Mn2+、Co2+、Ni2+浓度高达80mU M时，这些效应不明显，而Cu2+浓度达80mU M时，Cd~(2+)或Pb2+浓度达8mU M时，表现出与80mM浓度的氯化锌相似的效应。以锌奎宁为特异性探针，单细胞荧光跟踪细胞内锌离子的变化。分离的肝细胞内游离锌离子浓度为1.26×0.27微米，加入氯化锌后荧光强度呈浓度依赖性增加。CdCl2或PbCl2在8亩M时与ZnCl2在20-80亩M时有同样的效力，而NiCl2在80亩M时则无效。氯化锌可完全阻断高血糖素(CAMP)对糖酵解的抑制作用。胰高血糖素使细胞内锌离子显著下降。胰高血糖素和锌均通过增加糖原磷酸化酶的磷酸化来促进糖原分解，但对糖酵解的作用相反。锌克服了胰升糖素对丙酮酸激酶的失活作用，但不改变激素诱导的蛋白磷酸化。锌和cAMP对糖酵解的拮抗作用，以及由胰升糖素(CAMP)引起的游离锌浓度的迅速而显著的下降，可能表明锌作为糖代谢调节的重要介质的作用尚不清楚。
The effect of zinc ions on carbohydrate metabolism and intracellular Zn2+ was studied in hepatocytes from fed rats. The addition of ZnCl2 to the medium led to an almost 3-fold increase in lactate production and an increase in net glucose production of about 50%. Half-maximal rates occurred at about 40 mu M ZnCl2,. These effects were not seen with Mn2+, Co2+, up Ni2+ up to 80 mu M, whereas Cu2+ at 80 mu M and Cd2+ or Pb2+ at 8 mu M exhibited similar effects as 80 mu M ZnCl2. Changes in intracellular Zn2+ were followed by single cell epifluorescence using zinquin as a specific probe. Intracellular free Zn2+ in isolated hepatocytes was 1.26 a 0.27 mu M, and the addition of ZnCl2 led to a concentration-dependent increase in epifluorescence. CdCl2 or PbCl2 at 8 mu M was as potent as ZnCl2 at 20-80 mu M, whereas NiCl2 at 80 mu M was without effect. ZnCl2 completely abolished the inhibition of glycolysis by glucagon (cAMP). Glucagon led to a pronounced drop in cytosolic Zn2+. Both glucagon and zinc stimulated glycogenolysis by increasing the phosphorylation of glycogen phosphorylase but acted oppositely on glycolysis. Zinc overcame the inactivation of pyruvate kinase by glucagon without changing the hormone-induced protein phosphorylation. The antagonistic action of zinc and cAMP on glycolysis together with the rapid and marked decrease in free zinc concentration induced by glucagon (cAMP) may indicate an as yet unknown role of zinc as an important mediator of regulation of carbohydrate metabolism.