Bisphenol A Is More Potent than Phthalate Metabolites in Reducing Pancreatic β-Cell Function

Figure 3

Effect of incubation time and glucose concentration on insulin secretion. INS-1E cells were incubated with the indicated concentrations of BPA or the positive controls IBMX (25 μM) and Forskolin (0.25 μM) for (a) 2 h, (b) 24 h, or (c) 48 h before 1 h incubation with glucose-free KRBH buffer followed by 30 min incubation with 6.7 or 16.7 mM glucose in KRBH buffer. In addition, the insulin levels in the cell culture medium, containing 11.1 mM glucose, were measured after 48 h of stimulus incubation in (d) to test whether the positive control and BPA exposures exhausted the cellular insulin secretion. For these insulin analyses, the medium was harvested prior to the glucose stimulation in KRBH buffer. For all figures, indicates significant difference from negative control (2-way ANOVA, repeated measures, with Bonferroni posttest, (in a–c); 1-way ANOVA with Dunnett’s posttest, (in d)).

(a)

(b)

(c)

(d)