Fig. 4.

Effect of second messenger pathway inhibitors on GIP-augmented H⁺-Gly-Sar cotransport in IEC-6/CDX2 cells. GIP-augmented, H⁺-gradient-driven Gly-Sar absorption was measured and calculated for 5 min in 3–5 days postconfluent IEC-6/CDX2 cells grown on Transwell plates. GIP-augmented, H⁺-gradient-driven Gly-Sar absorption was also measured in the presence of Rp-cAMP (50 nM), wortmannin (Wort, 200 nM), calphostin (Cal C, 200 nM), or BAPTA (5 mM). Rp-cAMP, wortmannin, calphostin, and BAPTA were added individually to both chambers in the presence of serosal GIP. Cells treated with inhibitors in the absence of GIP were not significantly different than control. Results presented represent means ± SE of triplicate assays from 4 different experiments. *P < 0.05 compared with normal control; **P < 0.05 compared with GIP control.