Adenosine (Ado (also symbol A))

Adenosine is an endogenous purinergic nucleoside composed of adenine attached to ribose by a β-N9-glycosidic bond. It serves as one of the four fundamental building blocks for RNA synthesis and forms derivatives such as ATP/ADP/AMP that are central energy carriers within cells. Extracellularly, it functions as an autocrinal/paracrinal signal by activating four distinct G protein-coupled purinergic receptors—adenosinergic signaling regulates processes including cardiac rhythm control, vascular tone modulation, neuroprotection/neurotransmission regulation, inflammation suppression/promotion depending on context. Clinically administered intravenous adenosines exploit these properties primarily for acute arrhythmia termination and myocardial perfusion diagnostics. Its broad physiological role means that while it is essential biochemically and pharmacologically important when administered exogenously or targeted indirectly via its metabolic pathways/receptors—it should not be considered a direct “therapeutic target” like its cognate GPCRs.

Other names

Adenine ribosidebeta-D-AdenosineNucleocardyl9-beta-D-ribofuranosyladenine

For exogenous administration: Agonism at cardiac adenosine receptors, especially A1, leading to decreased AV nodal conduction time—antiarrhythmic effect. Vasodilation via A2a/A2b receptor activation, increasing coronary blood flow during diagnostic testing. For endogenous function: Acts through four G protein-coupled purinergic receptors to mediate diverse physiological responses including vasodilation/constriction, neurotransmission modulation, immune cell regulation.