Vasorelaxation in prostacyclin-hyperpolarized arterial smooth musculature

In arterial smooth muscle with normal tone or predepolarized and precontracted by noradrenaline, prostacyclin (10(-9) to 10(-6) M) effects a dose-dependent hyperpolarization and relaxation. The hyperpolarization is due to K+ channel opening. In this hyperpolarized portion of the stationary, sigmoid activation curve, vasodilation can be explained by means of Ca2+ channels that are closed between -40 mV and -80 mV in a voltage-dependent manner.