(±)-Norepinephrine is a racemic mixture of the endogenous neurotransmitter (–)-norepinephrine and (+)-norepinephrine. It induces cAMP accumulation in rat cerebral cortical membranes when used at concentrations ranging from 1 to 100 ?M.1 (±)-Norepinephrine induces contraction of bovine anterior cerebral, middle cerebral, and internal carotid arterial strips (EC50s = 0.91, 0.92, and 0.87 ?M, respectively) but induces relaxation of bovine posterior cerebral arterial strips (EC50 = 0.95 ?M).2
1.Tadokoro, C., Kiuchi, Y., Yamazaki, Y., et al.Behavioral stimulation without alteration of β and 5-HT receptors and adenylate cyclase activity in rat brain after chronic sertraline administrationPsychopharmacology (Berl.)130(2)124-130(1997) 2.Ayajiki, K., and Toda, N.Isolated bovine cerebral arteries from rostral and caudal regions: Distinct responses to adrenoceptor agonistsEur. J. Pharmacol.191(3)417-425(1990)