the effects of alpha-methyl substitution of epinephrine , norepinephrine and dopamine were investigated at alpha-1 , alpha-2 , beta-1 and beta-2 adrenoceptors in the pithed rat . alpha-methyl substitution of these three phenethylamines variably altered their capacity to elicit alpha adrenoceptor-mediated vasoconstriction , with slightly enhanced potency being observed for alpha-methyl substitution of norepinephrine and dopamine and a marked reduction in potency for alpha-methyl substitution of epinephrine .
C0028351
norepinephrine
C0014563
epinephrine