Mechanism of endothelin-1-(1—31)-induced calcium signaling in human coronary artery smooth muscle cells

We have found that human chymase produces a 31-amino acid endothelin [ET-1-(1—31)] from the 38-amino acid precursor (Big ET-1). We examined the mechanism of synthetic ET-1-(1—31)-induced intracellular Ca2+ signaling in cultured human coronary artery smooth muscle cells. ET-1-(1—31) increased the intracellular free Ca2+concentration ([Ca2+]i) in a concentration-dependent manner (10−14-10−10M). This ET-1-(1—31)-induced [Ca2+]iincrease was not affected by phosphoramidon, Bowman-Birk inhibitor, and thiorphan. The ET-1-(1—31)-induced [Ca2+]iincrease was not influenced by removal of extracellular Ca2+ but was inhibited by thapsigargin. ET-1-(1—31) at 10−12 M did not cause Ca2+ influx, whereas 10−7 M ET-1-(1—31) evoked marked Ca2+ influx, which was inhibited by nifedipine. ET-1-(1—31) also increased inositol trisphosphate formation. These results suggest that the ET-1-(1—31)-induced [Ca2+]iincrease at relatively low concentrations is attributable to the release of Ca2+ from inositol trisphosphate-sensitive intra...