A flow-activated chloride-selective membrane current in vascular endothelial cells

Shear stress-induced activation of endothelial ion channels, one of the ear liest responses to now, is implicated in mechano-signal transduction that r esults in the regulation of vascular tone. The effects of laminar flow on e ndothelial membrane potential were studied in vitro using both fluorescent potentiometric dye measurements and whole-cell patch-clamp recordings. The application of flow stimulated membrane hyperpolarization, which was revers ed to depolarization within 35 to 160 seconds. The depolarization was cause d by a Cl--selective membrane current activated by flow independently of th e K+ channel-mediated hyperpolarization. Thus, flow activated both K+ and C l- currents, with the net membrane potential being determined by the balanc e of the responses. Membrane potential sensitivity to flow was unchanged by flow preconditioning that elongated and aligned the cells.