drug competition studies , conducted in the presence of mg2+ and atp , indicated that ( -- ) -epinephrine , ( -- ) -norepinephrine , dopamine and serotonin had inhibitory constants ranging from 0.25 to 0.8 micron with ( -- ) -isoproterenol and tyramine having inhibitory constants around 2 micron .
C0014563
epinephrine
C0028351
norepinephrine