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An adrenergic agonist is a drug that stimulates a response from the adrenergic receptors.The five main categories of adrenergic receptors are: α 1, α 2, β 1, β 2, and β 3, although there are more subtypes, and agonists vary in specificity between these receptors, and may be classified respectively.
The mechanisms of sympathomimetic drugs can be direct-acting (direct interaction between drug and receptor), such as α-adrenergic agonists, β-adrenergic agonists, and dopaminergic agonists; or indirect-acting (interaction not between drug and receptor), such as MAOIs, COMT inhibitors, release stimulants, and reuptake inhibitors that increase the levels of endogenous catecholamines.
β 1-Adrenergic receptor agonists, also known as beta-1 agonists, are a class of drugs that bind selectively to the β 1-adrenergic receptor. As a result, they act more selectively upon the heart . β-Adrenoceptors typically bind to norepinephrine release by sympathetic adrenergic nerves and to circulating epinephrine .
Activation of β 2 receptors induces smooth muscle relaxation in the lungs, gastrointestinal tract, uterus, and various blood vessels. Increased heart rate and heart muscle contraction are associated with the β1 receptors; however, β 2 cause vasodilation in the myocardium. [citation needed] β3 receptors are mainly located in adipose tissue. [5]
The action of drugs on the human body (or any other organism's body) is called pharmacodynamics, and the body's response to drugs is called pharmacokinetics. The drugs that enter an individual tend to stimulate certain receptors, ion channels, act on enzymes or transport proteins. As a result, they cause the human body to react in a specific way.
A parasympathomimetic drug, sometimes called a cholinomimetic drug [1] or cholinergic receptor stimulating agent, [2] is a substance that stimulates the parasympathetic nervous system (PSNS). [ 3 ] [ 2 ] These chemicals are also called cholinergic drugs because acetylcholine (ACh) is the neurotransmitter used by the PSNS.
Alpha 2 receptors are associated with sympatholytic properties. Alpha-adrenergic agonists have the opposite function of alpha blockers . Alpha adrenoreceptor ligands mimic the action of epinephrine and norepinephrine signaling in the heart, smooth muscle and central nervous system, with norepinephrine being the highest affinity.
The beta-1 adrenergic receptor (β 1 adrenoceptor), also known as ADRB1, can refer to either the protein-encoding gene (gene ADRB1) or one of the four adrenergic receptors. [5] It is a G-protein coupled receptor associated with the Gs heterotrimeric G-protein that is expressed predominantly in cardiac tissue. In addition to cardiac tissue, beta ...