Mechanical stress-induced Ca2+ entry and Cl- current in cultured human aortic endothelial cells

A fluid stream through a microtube was applied to cultured human aortic endothelial cells to investigate the endothelial responses of bath the ionic currents and intracellular Ca2+ concentration ([Ca2+](i)) to mechanical stimulation. The fluid stream induced an increase in [Ca2+](i) that was dependent on both the flow rate and the extracellular Ca2+ concentration. Gd3+ and niflumic acid inhibited the fluid stream-induced increase in [Ca2+](i), whereas Ba2+ and tetraethylammonium ion exhibited no effect. The fluid stream-induced [Ca2+](i) increase was accompanied by the activation of an inward current at -52.8 mV. The reversal potential of the fluid stream-induced current shifted to positive potentials when the external Cl- concentration was reduced but was not affected by variation of the external Naf concentration. During the exposure to the fluid stream, [Ca2+](i) was voltage dependent, i.e., depolarization decreased [Ca2+](i). We therefore conclude that the fluid stream-induced current is largely carried by Cl- and that the Cl- current may thus play a role in modulating the Ca2+ influx by altering the membrane potential of endothelial cells.