although synthetic alpha 2-adrenergic agents failed to influence isoproterenol inhibitory effect , our study shows that prestimulation of beta-adrenoceptors by isoproterenol , followed by addition of adrenaline or noradrenaline markedly diminished the inhibitory effect of isoproterenol to a level close to that which characterized the inhibition observed with catecholamines , when tested alone .
C0014563
adrenaline
C0028351
noradrenaline