|Briske Anderson, Mary|
Submitted to: Federation of American Societies for Experimental Biology Conference
Publication Type: Abstract Only
Publication Acceptance Date: April 18, 1998
Publication Date: N/A
Technical Abstract: Previously we showed that copper (Cu) uptake in Caco-2 cells cultured in high media zinc (Zn) concentrations was enhanced and that Cu transport was reduced (Reeves, et al., J.Nutr. 126:1701, 1996). Here we show that physiologic Zn concentrations also affect Cu movement into and out of Caco-2 cells. Cells were seeded onto Falcon membranes with high pore density and maintained in DME medium supplemented with 10% FBS, nonessential amino acids, glucose, and glutamine. This medium normally contained 0.5 uM Cu and 5 uM Zn. In one experiment the cells were exposed to Zn (5 & 25 uM) from d 15 to 21. Then, Cu uptake and transport, in both apical and basolateral directions, were measured by using 64**Cu. In another experiment, Zn exposed cells were labeled with 64**Cu and a timed release of the label to the apical and basolateral sides was performed. Cells exposed to 25 uM Zn had a 30% higher uptake rate of 64**Cu from the apical side than those exposed to 5 uM. There was no effect of Zn on uptake from the basolateral side, even though this rate was 3-fold higher than the apical rate. Transport of 64**Cu across the cell layer was 50% less after 160 min in those cells exposed to 25 æM Zn whether measured from the apical or basolateral side. Transport rates in both directions were similar. The rate of release of 64**Cu from the cell to the apical side was not affected by media Zn concentration; however, release to the basolateral side was reduced by 35% by the higher Zn concentration. The cell concentration of Zn was proportional to the media Zn concentration. Although the data suggest that high cellular Zn was inhibiting the Cu transporter, there was not an accumulation of cellular Cu in the high Zn group.