Urapidil(64887-14-5) is an antagonist of α
1-adrenergic receptors (α
1-ARs) and a partial agonist of the serotonin (5-HT) receptor subtype 5-HT
1A.
1,2 It selectively binds to α
1- over α
2-ARs (IC
50s = 0.74 and 42 μM, respectively) and to 5-HT
1A over 5-HT
1B and 5-HT
2 receptors (IC
50s = 0.4, 20.4, and >10 μM, respectively) in rat cortex.
1 Urapidil inhibits cAMP accumulation induced by forskolin in calf hippocampus as a functional model for 5-HT
1A receptors (EC
50 = 390 nM).
3 It is also a β
1-AR antagonist that inhibits the positive chronotropic response induced by isoproterenol (Item No.
15592) in isolated rat atria (pA
2 = 6.05).
4 Urapidil (1 μmol/kg, i.v.) lowers mean arterial pressure (MAP) in anesthetized cats, an effect that is reduced by central administration of the 5-HT
1A receptor antagonist spiroxatrine.
5