Potent block of volume-activated chloride currents in endothelial cells by the uncharged form of quinine and quinidine

摘要

1 The effects of quinine and quinidine on the volume-activated chloride current (I_(Cl(vol))) in cultured endothelial cells from bovine pulmonary artery were studied by use of the whole-cell patch-clamp technique. 2 At pH 7.4 both quinine and quinidine induced a fast and reversible block of I_(Cl(vol)) with K_i values of 20 ± 4 μM and 30±10 μM, respectively. 3 The blocking efficiency of both drugs increased dramatically with increasing extracellular pH,' indicating that the blockade is mediated by the uncharged form of quinine and quinidine. 4 These results suggest a hydrophobic interaction with high affinity between volume-activated chloride channels and uncharged quinine and quinidine within the membrane bilayer of endothelial cells.