what are the differences between epinephrine and norepinephrine?

[Holly D]

are they the same? if not can you tell me the difference and give me an example if you can...thanks!

[tinmuning]

Hi holly! Both are hormones secreted by the adrenal gland (medulla to be exact) & the nerve endings. Both interact in several body receptors (i.e. alpha & beta) and their binding to these sites cause different effects. They may have similar effects like when they bind to alpha receptors, they can cause vasoconstriction. However, unlike epinephrine, norepinephrine cannot be used in cases of asthma. Norepinephrine is primarily used in cases of shock.