Molecular mechanism of endothelin-1 action on aortic cells. 
The vasoconstricting action of endothelin-1 (ET-1) is partly mediated by voltage-dependent L-type Ca2+ channels.  Activation of the Ca2+ channels is indirect.  ET-1 action involves (i) the hydrolysis of phosphatidylinositol and the release of Ca2+ from internal stores and (ii) the opening of a nonselective cation channel in the plasma membrane.  The resulting depolarization triggers the activity of L-type Ca2+ channels.