Prozialeck W C, Lamar P C
Department of Pharmacology, Chicago College of Osteopathic Medicine, Downers Grove, IL 60515.
Arch Toxicol. 1993;67(2):113-9. doi: 10.1007/BF01973681.
Recent studies have shown that Cd2+ has relatively specific damaging effects on cell-cell junctions in the renal epithelial cell line, LLC-PK1. The objective of the present studies was to examine the surface binding and uptake of Cd2+ by LLC-PK1 cells in relation to the disruption of cell-cell junctions. LLC-PK1 cells on Falcon Cell Culture Inserts were exposed to CdCl2 containing trace amounts of 109Cd2+ from either the apical or the basolateral compartments, and the accumulation of 109Cd2+ was monitored for up to 8 h. The integrity of cell-cell junctions was assessed by monitoring the transepithelial electrical resistance. The results showed that the cells accumulated 3-4 times more Cd2+ from the basolateral compartment than from the apical compartment. The accumulation of Cd2+ from the basolateral compartment occurred in two phases: a rapid, exponential phase that occurred in 1-2 h and coincided with a decrease in transepithelial resistance, and a slower, linear phase that continued for 6-8 h. The Cd2+ that accumulated during the rapid phase was easily removed by washing the cells in EGTA, indicating that most of it was bound to sites on the cell surface. By contrast, most of the Cd2+ that accumulated during the slower phase could not be removed by EGTA, indicating that it had been taken up by the cells. Additional studies showed that the rapid phase of Cd2+ accumulation was enhanced when Ca2+ was present at low concentrations (0.1 mM), and was greatly reduced when Ca2+ was present at high concentrations (10 mM).(ABSTRACT TRUNCATED AT 250 WORDS)
最近的研究表明，镉离子（Cd2+）对肾上皮细胞系LLC-PK1中的细胞间连接具有相对特异性的破坏作用。本研究的目的是检测LLC-PK1细胞对Cd2+的表面结合和摄取情况，并探究其与细胞间连接破坏的关系。将接种于Falcon细胞培养插入物上的LLC-PK1细胞，从顶侧或基底外侧隔室暴露于含有微量109Cd2+的氯化镉（CdCl2）中，并监测109Cd2+的累积情况，最长监测8小时。通过监测跨上皮电阻来评估细胞间连接的完整性。结果显示，细胞从基底外侧隔室积累的Cd2+比从顶侧隔室多3 - 4倍。从基底外侧隔室积累Cd2+分两个阶段：快速的指数阶段发生在1 - 2小时，与跨上皮电阻降低同时出现；较慢的线性阶段持续6 - 8小时。快速阶段积累的Cd2+通过用乙二醇双四乙酸（EGTA）洗涤细胞很容易被去除，这表明大部分Cd2+与细胞表面位点结合。相比之下，较慢阶段积累的大部分Cd2+不能被EGTA去除，这表明它已被细胞摄取。进一步的研究表明，当钙离子（Ca2+）浓度较低（0.1 mM）时，Cd2+积累的快速阶段增强；当Ca++浓度较高（10 mM）时，该阶段则大大降低。（摘要截短于250字）
