FIGURE 7.

Inhibition of PIP₂ synthesis by lipid kinase inhibitors affects Ace-stimulated I_Cl. A, pre-incubation with two different concentrations of Wort50 (50 μm), Wort1 (1 μm), PAO (10 μm), and PLL (25 μg/ml) significantly inhibited Isc in Caco-2 cells. NS, statistically not significant. B, following a 30-min incubation in the presence of PAO (20 μm) and PLL (25 μg/ml), Isc was reduced in response to Ace (5 μm) in mouse ileum. C, PIP₂ speeds Isc recovery by subsequent washout of PAO. PIP₂ modulators were added to both sides of the solutions. Ace was added only on the apical side. D, Western blot (with PIP5K antibody) detection of proteins in total lysate of wild-type Caco-2, vector control, and PIP5K knock out cells. Anti-GAPDH was used to confirm equal loading (n = 3). E, representative time course on the effect of Ace on Isc in PIP5K KO Caco-2, WT, and vector control cells. PIP5K knock-out cells had very little or no effect in response to Ace stimulated Isc. The inset shows the summary of the data from six such monolayers. Values represent means ± S.E. significant difference at *, p < 0.05, or **, p < 0.01when compared with the corresponding control value by ANOVA.