The four primary receptors — alpha-1, alpha-2, beta-1, and beta-2 — are located in different body areas. The impact of norepinephrine and epinephrine depend on which receptors they activate.

The AMPA group of brain receptors have mostly been assumed to be calcium impermeable and so were not thought to contribute to the calcium-dependent mechanisms underlying learning and memory.

Alpha receptor agonists are substances that activate the sympathetic nervous system by stimulation of alpha receptors, similar to the effects of epinephrine and norepinephrine. Alpha receptors are ...