Lilien D L, Spivak J L, Goldman I D
J Clin Invest. 1970 Aug;49(8):1551-7. doi: 10.1172/JCI106372.
Chromium is a trace metal of importance in human physiology and, in addition, as 51-chromate, has been extensively used as a label in the study of blood cell pool sizes and intravascular kinetics. The transport characteristics of 51-chromate were investigated in normal human leukocytes. Chromate uptake is unidirectional over a 1 hr incubation with extracellular chromate concentrations up to 200 mumoles/liter. Under these conditions, intracellular 51-chromium is in a form in which it is nonexchangeable. Influx is temperature sensitive with a Q(10) of approximately 2 and may be energy dependent since a variety of metabolic poisons strongly inhibit uptake. The unidirectional influx of chromate follows Michaelis-Menten kinetics; the maximum velocity is 52 mmumoles/g dry weight of cells per min and the chromate concentration at which influx velocity is half maximal is 87 mumoles/liter. This transport mechanism is highly specific for chromate; other divalent tetrahedral anions only slightly inhibit influx at concentrations up to 10 times that of chromate. Metavanadate, however, competitively inhibits chromate influx at equimolar concentrations. Exposure of cells to unlabeled chromate leads to inhibition of subsequent influx of 51-chromate. It is suggested that this is due to a primary inhibitory effect of chromate on cellular energy metabolism.
铬是人体生理学中一种重要的痕量金属，此外，作为51 - 铬酸盐，它已被广泛用作研究血细胞池大小和血管内动力学的标记物。对正常人类白细胞中51 - 铬酸盐的转运特性进行了研究。在细胞外铬酸盐浓度高达200微摩尔/升的情况下，经过1小时的孵育，铬酸盐的摄取是单向的。在这些条件下，细胞内的51 - 铬处于一种不可交换的形式。流入对温度敏感，Q(10)约为2，并且可能依赖能量，因为多种代谢毒物会强烈抑制摄取。铬酸盐的单向流入遵循米氏动力学；最大速度为每分钟每克细胞干重52微摩尔，流入速度为最大值一半时的铬酸盐浓度为87微摩尔/升。这种转运机制对铬酸盐具有高度特异性；其他二价四面体阴离子在浓度高达铬酸盐浓度10倍时仅轻微抑制流入。然而，偏钒酸盐在等摩尔浓度下竞争性抑制铬酸盐流入。将细胞暴露于未标记的铬酸盐会导致随后51 - 铬酸盐流入的抑制。据推测，这是由于铬酸盐对细胞能量代谢的主要抑制作用所致。
