experiments on rat mesenteric arterioles , metarterioles , and aortae demonstrate that although alpha-methylnorepinephrine is much less potent in inducing contraction than epinephrine on all three blood vessel types , it is either equivalent or only one and a half to two times less potent than the natural postganglionic neurotransmitter , norepinephrine , on these blood vessels .
C0014563
epinephrine
C0028351
norepinephrine