Epinephrine

Epinephrine is the primary 'fight-or-flight' hormone and works together with norepinephrine to induce its spectacular responses.

Epinephrine works to rapidly mobilize energy-yielding fuels, including glucose from the liver (through glycogenolysis and gluconeogenesis) and fatty acids from adipose tissue.

Epinephrine is secreted from the adrenal medulla in response to hypoglycemia, stress, trauma, or extreme exercise. Its release is largely controlled by the CNS via preganglionic sympathetic fibres.

The biologic effects of the catecholamines are very brief, lasting for only 10 seconds in the case of epinephrine. Enzymes including COMT and MOA convert them to vannilylmandelic acid (VMA), which can be measured in the urine.

 

Effects on the Cardiovascular System

 

Effects on Renal System

 

Effects on Carbohydrate Metabolism

 

Effects on Lipid Metabolism

 

Adrenergic Receptors

Generally, the various adrenoreceptors can bind both epinephrine and norepinephrine, though with different affinities.

Adrenoreceptors
  Intracellular Effect location Physiologic Effect
α1 inc IP3 and DAG lead to inc Ca2+   peripheral vasoconstriction by SMCs
α2 dec [cAMP]   vasoconstriction in some vessels, Na uptake in the proximal tubule
β1 inc [cAMP] heart increases heart rate and contractility
β2 inc [cAMP] arterioles vasodilation
β3 inc [cAMP]