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Background and objective Endothelin-1 (ET-1) is a potent mitogen involved in cell growth in human lung adenocarcinoma cells SPC-A1. The increase in intracellular free calcium ([Ca2+]i) plays a great role in this process. The aim of this study is to investigate the ET-1-induced [Ca2+]i responses in SPC-A1 cells and to explore its cellular mechanism. Methods [Ca2+]i was measured by Fura-2/AM fluorescent assay. Endothelin receptors antagonists, calcium channel blockers and intracellular signal transduction blockers were used to study the underlying mechanism of ET-1-induced [Ca2+]i responses in SPC-A1 cells. Results At the concentration of 1×10-15 mol/L-1×10-8 mol/L, ET-1 caused a dose-dependent increase of [Ca2+]i in SPC-A1 cells (P<0.05) in vitro. The ET-1-induced (1×10-10 mol/L) increase of [Ca2+]i was blocked by BQ123 at 1×10-7 mol/L (P<0.05), a highly selective endothelin receptor A (ETAR) antagonist, not by BQ788 at 10-7 mol/L (P>0.05), a highly selective endothelin receptor B (ETBR) antagonist. Depletion of extracellular Ca2+ with free Ca2+ solution and 0.1mmol/L ethyleneglycol bis (2-aminoethyl ether) tetraacetic acid (EGTA) or blockade of voltage dependent calcium channel with nifedipine at 1×10-6 mol/L significantly reduced the ET-1-induced increase of [Ca2+]i. The ET-1-induced (1×10-10 mol/L) increase of [Ca2+]i was also significantly attenuated by U73122 at 1×10-5 mol/L (P<0.05), a phospholipase C inhibitor, and by Ryanodine at 50×10-6 mol/L. However, Staurosporine (2×10-9 mol/L), a protein kinas C inhibitor, exerted no significant effect on the ET-1-induced (1×10-10 mol/L) increase of [Ca2+]i. Conclusion ET-1 elevates [Ca2+]i via activation of ETA receptor. Both phospholipase C/Ca2+ pathway and Ca2+ influx through voltage dependent Ca2+ channel activate by ETAR contribute to this process.