Norepinephrine-induced intracellular Ca2+ release from vascular smooth muscle.

In rabbit aorta and superior mesenteric artery, application of NE causes release of Ca2+ from an intracellular Ca2+ store, probably SR. The amount of released Ca2+ is sufficient to activate the myofilaments submaximally. It is suggested that NE mediates Ca2+ release by a rapid increase in the free Ca2+ concentration near the SR (Ca2+-induced Ca2+ release). The uptake of Ca2+ into the store and the Ca2+-induced Ca2+ release is modulated by c-AMP.