The endothelial volume-regulated anion channel, VRAC

We discuss in this short review properties of a volume-regulated anion channel that we have described in vascular endothelial cells. This channel, VRAC (volume-regulated anion channel) is outwardly rectifying with single channel conductances between 10-20pS for inward currents and 40-50pS for outward currents. VRAC is permeable for a wide range of anions, amino acids and organic osmolytes. The estimated pore diameter is approximately 1.1nm. VRAC is gated by a probably complex mechanism in which changes in ionic strength, tyrosine phosphorylation, the cytoskeletal organiser RhoA and possibly caveolin are essentially involved. The molecular candidate for this channel is still elusive. The functional impact of VRAC as a possible mechano-sensor in endothelium and as a regulatory component in the cell cycle, endothelial cell proliferation and possible angiogenesis will be discussed.