Reticuline (3 μM, 30 μM, 300 μM, 900 μM and 1.5 mM) inhibits in a concentration-dependent manner the contractions induced by Phenylephrine (1 μM), KCl (80 mM) and KCl (30 mM), (IC ₅₀ =40±10, 240±40 and 300±40 μM, respectively) in isolated rat aortic rings with intact endothelium.
Reticuline (3 μM, 30 μM, 300 μM, 900 μM and 1.5 mM) antagonizes CaCl ₂ -induced contractions, and also inhibits the intracellular calcium dependent transient contractions induced by Norepinephrine (1μM), but not those induced by Caffeine (20 mM).

Reticuline (5, 10 and 20 mg/kg, i. v., randomly) injections produced an intense hypotension in normotensive rats. The hypotensive effect of Reticuline is probably due to a peripheral vasodilation in consequence of: 1) muscarinic stimulation and NOS activation in the vascular endothelium, 2) voltage-dependent Ca ²⁺ channel blockade and/or 3) inhibition of Ca ²⁺ release from norepinephrine-sensitive intracellular stores.