Adrenergic receptor

Adrenergic receptors are cell-surface receptors activated by adrenaline or noradrenaline. Their signaling changes functions such as heart rate, blood vessel tone, and smooth-muscle activity.

G protein-coupled receptor: A membrane receptor that activates intracellular G proteins when a ligand binds. Adrenergic receptors belong to this receptor family and signal through its molecular machinery.
Alpha-1 adrenergic receptor: An adrenergic receptor subtype that primarily signals through Gq proteins. It is a major subtype whose activation commonly contracts vascular smooth muscle.
Beta blocker: A drug that antagonizes beta-adrenergic receptors. These drugs reduce selected effects of endogenous catecholamines, especially on the heart.
Fight-or-flight response: A rapid physiological response to threat that mobilizes energy and prepares the body for action. Adrenergic activation supplies many of its cardiovascular and metabolic effects.
G protein: A molecular switch that relays signals from membrane receptors to intracellular effectors. Activated adrenergic receptors regulate G proteins to begin downstream signaling.
Alpha-2 adrenergic receptor: An adrenergic receptor subtype that primarily signals through Gi proteins. It often limits neurotransmitter release and sympathetic outflow.
Beta-2 agonist: A drug that activates beta-2 adrenergic receptors, often to relax airway smooth muscle. This drug class uses receptor subtype selectivity to treat bronchoconstriction.
Vasoconstriction: Narrowing of blood vessels caused by contraction of vascular smooth muscle. Alpha-1 receptor activation produces vasoconstriction in many vascular beds.
Adenylyl cyclase: An enzyme that produces cyclic AMP from ATP. G proteins regulated by adrenergic receptors can increase or decrease this enzyme’s activity.
Beta-1 adrenergic receptor: An adrenergic receptor subtype concentrated in the heart and juxtaglomerular cells. Its activation increases cardiac activity and promotes renin release.

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