Figure 16-10 Release and reuptake of norepinephrine at sympathetic nerve terminals. aad, aromatic L-amino decarboxylase: DβH, dopamine β-hydroxylase; dopa, L-dihydroxyphenyalanine; NE, norepinephrine; tyr hyd, tyrosine hydroxylase; solid circle, active carrier. (From Vanhoutte PM: Adrenergic neuroeffector interaction in the blood vessel wall. Fed Proc 37:181, 1978 as modified by Shepherd J, Vanhoutte P: Neurohumoral regulation. In Shepherd S, Vanhoutte P [eds]: The Human Cardiovascular System: Facts and Concepts. New York, Raven Press, 1979, p 107.)