the rank-order of potency of several adrenergic agonists in potentiating the effect of vip on camp levels is the following : epinephrine greater than ne greater than phenylephrine much greater than clonidine , with ec50 of 2.2 , 5 , and 10 microm , respectively ( clonidine being only marginally effective ) .
C0014563
epinephrine
C0028351
ne