Adenosine receptors and transporters (AR/ENT)

The adenosine system comprises a group of cell-surface G protein-coupled receptors (A1, A2A, A2B, and A3) and specialized transport proteins, primarily the equilibrative nucleoside transporters (ENT1 and ENT2), that regulate the extracellular concentration and signaling of adenosine [Source: IUPHAR/BPS Guide to Pharmacology]. Adenosine acts as a ubiquitous endogenous modulator, typically signaling "energy depletion" or "cellular stress" to protect tissues [Source: StatPearls]. In the cardiovascular system, it induces vasodilation and slows heart rate, while in the central nervous system, it generally acts as an inhibitory neuromodulator promoting sleep [Source: PubMed, PMID: 28651634]. In oncology, the adenosine pathway is a key metabolic checkpoint, where high extracellular adenosine levels in the tumor microenvironment suppress immune cell activity, leading to the development of A2A and A2B receptor antagonists as potential immunotherapies [Source: Nature Reviews Drug Discovery]. Pharmacological intervention involves either direct receptor modulation or the inhibition of adenosine uptake to prolong its local signaling effects [Source: PubChem].

Other names

Adenosinergic systemP1 receptorsEquilibrative nucleoside transportersAdenosine uptake sites

Inhibition of adenosine reuptake via equilibrative nucleoside transporters (ENTs) to increase extracellular adenosine levels, and modulation of G protein-coupled adenosine receptors (A1, A2A, A2B, and A3) to trigger intracellular signaling cascades.