Cerebrovascular reactivities to N-methylated catecholamines in humans, monkeys and dogs

A comparison was made of the cerebrovascular responses of humans, monkeys and dogs to noradrenaline (NAd) and dopamine (DA) as well as to their N-methylated derivatives, adrenaline (Ad) and N-methyl dopamine (methyl DA). The present experiments demonstrated that N-methylation of both NAd and DA enhanced the contractile responses of these agents in human cerebral arteries, while only N-methylation of DA enhanced the contraction of monkey cerebral arteries, and such an enhancement was not seen in dog cerebral arteries.