Direct modulation of volume-regulated anion channels by Ca2+ chelating agents

Ca 2+ chelating agents are widely used in biological research for Ca 2+ buffering. Here we report that BAPTA, EDTA and HEDTA produce fast, reversible, voltage-dependent inhibition of swelling-activated Cl 3 current (ICl;swell) in LNCaP prostate cancer epithelial cells that is unrelated to their Ca 2+ binding. BAPTA was the most effective (maximal blockade 67%, IC50 =7 0 W WM, at +100 mV) followed by EDTA and HEDTA. ICl;swell blockade by EDTA was pH-dependent. BAPTA blocked ICl;swell also in other cell types. We conclude that Ca 2+ chelating agents block ICl;swell by acting directly on the underlying channel, and that the negative charge of the free chelator form is critical for the blockade. 4 2002 Published by Elsevier Science B.V. on behalf of the Federation of European Biochemical Societies.