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

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Abstract
A fluid stream through a microtube was applied to cultured human aortic endothelial cells to investigate the endothelial responses of both the ionic currents and intracellular Ca2+concentration ([Ca2+]i) to mechanical stimulation. The fluid stream induced an increase in [Ca2+]ithat 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+]iincrease 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 Na+ concentration. During the exposure to the fluid stream, [Ca2+]iwas 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.