The chemical formula of adrenaline is C9H13NO3, and the medical term for adrenaline is epinephrine. In the body, epinephrine, along with its molecular precursors norepinephrine (NE) and dopamine (DA), is derived from the aromatic amino acid tyrosine. Collectively, these neurotransmitters are called catecholamines.
Epinephrine is produced by neurons in the brain and sympathetic nervous system and chromaffin cells in the adrenal medulla. The conversion of tyrosine to epinephrine is a four-step process. First, tyrosine hydroxylase adds an -OH group to tyrosine's aromatic ring. This turns tyrosine into dihydroxyphenylalanine or DOPA. Next, DOPA decarboxylase removes the COOH group from the alpha carbon to create dopamine. Third, DA hydroxylase adds another hydroxyl group to the beta carbon to make NE. Finally, the enzyme PNMT, or phenylethanolamine N-methyltransferase, adds a methyl group to the nitrogen atom to make epinephrine.
Physiologically, catecholamines increase heart rate and blood pressure as part of the fight-or-flight response. In medicine, epinephrine is used in emergency situations to dilate the airways during life-threatening allergic reactions such as a bee sting. It is also used as a pressor, meaning a drug that raises blood pressure in shock victims. NE and DA are also used as pressors in critical care medicine.