Figure 7.

Effect of mucin zinc saturation on zinc uptake by enterocytes. The impact of the degree of zinc saturation of extracellular added mucins on zinc uptake in Caco-2 cells is shown by measuring the increase of free zinc using the fluorescent zinc probe Zinpyr-1. Porcine mucins were incubated with 2500 µM, 5000 µM and 10,000 µM zinc, resulting in mucins with differing zinc content (low, medium, high) and degree of zinc saturation. (A) Zinc absorption of Caco-2 cells after 40 min of treatment with 25 µM zinc alone or with zinc-loaded mucins, diluted to a final zinc concentration of 25 µM zinc (final mucin concentration: 1 mg/mL low zinc mucin, 0.46 mg/mL medium zinc mucin, 0.31 mg/mL high zinc mucin). (B) Zinc uptake after 40 min incubation with 0 µM or 25 µM zinc in the presence of 0 mg/mL or 0.25 mg/mL zinc-loaded or zinc-depleted mucins, respectively. Data are presented as means + SEM of at least three independent experiments. Significant differences were analyzed by repeated-measures ANOVA with the Bonferroni post hoc test. Bars sharing a letter (a, b, c, d) are not significantly different.