Figure 1.

HPLC analysis of inositol polyphosphate levels after S. dublin infection of T₈₄ human colonic epithelial cells. [³H]Inositol-labeled T₈₄ monolayers were infected with S. dublin, and inositol polyphosphates were extracted and analyzed by an HPLC system that resolves three InsP₄ peaks, as demonstrated (17). (a) A representative radiochromatogram from control cells (top) and cells infected for 30 min with S. dublin (bottom). Arrows indicate elution times of known inositol phosphate standards. The Ins(3,4,5,6)P₄/Ins(1,4,5,6)P₄ peak was collected and analyzed as described in Materials and Methods and found to consist of 84 ± 5% (mean ± SEM, n = 3) Ins(1,4,5,6)P₄ after S. dublin infection, with the remainder being Ins(3,4,5,6)P₄. In unstimulated cells, the same peak contained approximately equal amounts of both isomers (data not shown) (6). (b) A time course of the levels of InsP₅ (•), Ins(1,4,5,6)P₄ (○), InsP₃-Z (▿), and InsP₂-X and Y (▾). Data are displayed as the fraction of radioactivity associated with the specific InsP_x relative to the total radioactivity in all cellular InsP_x.