Figure 2.

Treatment of HT-29 cells with the selective NHE inhibitors amiloride (A), MIA (B), or EIPA (C) suppresses mannitol-induced IL-8 production. Treatment of HT-29 cells with the nonamiloride NHE inhibitors cimetidine (D), clonidine (E), or harmaline (F), reproduces the suppressive effect of selective NHE inhibitors on the production of IL-8 by mannitol-induced HT-29 cells. When harmaline was used, supernatants for IL-8 measurement were taken 4 hours after the hyperosmotic challenge. In the case of amiloride, MIA, EIPA, cimetidine, and clonidine, IL-8 levels were measured from supernatants obtained 18 hours after the hyperosmotic challenge. Hyperosmotic medium prepared by the addition of 100 mmol/L of mannitol to isosmolar growth medium was used for hyperosmotic stimulation. Data are mean ± SEM of n = 6 to 12 wells from two different experiments. *, P < 0.05; **, P < 0.01. Dotted bar, no mannitol; cross-hatched bars, mannitol.