Phosphoinositide and phosphatidate changes in BHK cells in response to Ca influx via NCX1. The bar graphs represent the relative phospholipid concentrations, as percent of total anionic phospholipid, for cells under control conditions (control), cells treated with 25 μM nystatin in the absence of Ca for 10 min (nystatin − Ca), and nystatin-treated cells that were exposed to 4 mM extracellular Ca for 1 min (nystatin + Ca).