thus , while epinephrine , norepinephrine and dopamine all produced vasoconstriction that was mediated equally by postsynaptic vascular alpha-1 and alpha-2 adrenoceptors , their corresponding alpha-methyl-substituted derivatives produced vasoconstriction exclusively by activation of postsynaptic vascular alpha-2 adrenoceptors .
C0014563
epinephrine
C0028351
norepinephrine