Epinephrine naturally occurring catecholamine

The three naturally occurring catecholamines dopamine, NE, and epinephrine are used as therapeutic agents. 

The naturally occurring catecholamines dopamine (1), norepinephrine (2), and epinephrine(3) (Figure 1) play key roles in neurotransmission, metabolism, and in the control of various physiological processes. For example, norepinephrine is the primary neurotransmitter in the sympathetic nervous system and also functions as a neurotransmitter in the central nervous system. Epinephrine, elaborated by the adrenal gland, has potent effects on the heart, vascular and other smooth muscles. Dopamine is an important neurotransmitter in the central nervous system, and has important peripheral effects in such organs as the kidney and heart. The importance of these effects has made the search for drugs that can mimic, inhibit, or otherwise modulate the effects of these catecholamines an important area of medicinal chemistry. 

Figure 1 Naturally occurring catecholamines Dopamine (1), norepinephrine (2), and epinephrine (3).

Mimic naturally occurring catecholamines (epinephrine, norepinephrine and dopamine) or stimulate the release of norepinephrine Indications Alpha-adrenergic agonists used to treat hypotension Common drug examples ... 

The naturally occurring catecholamines—dopamine (DA) (1), / -norepinephrine (/ -NE) (2), and / -epinephrine (/J-EPI) (3)— have many imiK)rtant biological functions. These catecholamines are produced in vivo from L-tyrosine. Tyrosine is first converted to dihydroxyphenylalanine (DOPA) by aromatic hydroxylation. L-DOPA is then decarboxylated to give DA, which is subsequently converted to / -NE by p-hydroxylation. DA is a vital neurotransmitter in the central nervous system (CNS) and has actions on the kidneys and heart. Norepinephrine is also present as a neurotransmitter in the CNS, and is the principal neurotransmitter of the peripheral sympathetic nervous system. Epinephrine, which is elaborated from / -NE by N-methylation in the adrenal medulla, has potent actions on the heart, smooth muscle, and other organs (/). 

The adrenomimetic drugs can be divided into two major groups on the basis of their chemical structure the catecholamines and the noncatecholamines. The catecholamines include norepinephrine, epinephrine, and dopamine, all of which are naturally occurring, and several synthetic substances, the most important of which is isoproterenol (isopropyl norepinephrine). The skele-... 

The most well known of the naturally occurring phenethylamine derivatives (Table I) are the transmitters of the sympathetic nervous system, epinephrine, norepinephrine, and dopamine. All these compounds are 3,4-dioxygenated in the aromatic nucleus and are collectively known as the catecholamines. Norepinephrine is the transmitter of most sympathetic postganglionic fibers, dopamine is the predominant transmitter of the mammalian extrapyramidal system and of several mesocortical and mesolimbic neuronal pathways, and epinephrine is the major hormone of the adrenal medulla (363). The literature that has accumulated on the action of these compounds in higher animals is enormous. Metanephrine and normetanephrine are known from animals as deactivated metabolites of epinephrine and norepinephrine that result from the action of the enzyme catechol O-methyltransferase (364). 

Epinephrine [ep ee NEF rin] is one of five catecholamines—epinephrine, norepinephrine, dopamine, dobutamine, and isoproterenol—commonly used in therapy. The first three catecholamines occur naturally, the latter two are synthetic compounds (see Figure 6.7). Epinephrine is synthesized from tyrosine in the adrenal medulla and released, along with small quantities of norepinephrine, into the blood stream. Epinephrine interacts with both a and p receptors. At low doses, p effects (vasodilation) on the vascular system predominate, whereas at high doses, a effects (vasoconstrictor) are strongest. 

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