Rapid increase in plasma nitrite concentration following intravenous administration of nipradilol

Nipradilol, a beta-adrenoceptor antagonist with vasodilator activity, has a structure which contains a NO2 group. In anesthetized dogs, the time course of the systemic vasodilation and plasma nitrite (NO2-) concentration was studied following intravenous administration of nipradilol (1 mg/kg). A fall in systemic vascular resistance was observed at 1 min, which was rapidly followed by a significant increase in the plasma NO2- concentration. It is indicated that nipradilol exerts systemic vasodilatation via nitric oxide (NO) release in vivo.