a1ar

A1AR, typically written A1AR or a1ar, refers most often to the adenosine A1 receptor, a G protein–coupled receptor that binds the nucleoside adenosine. In humans, it is encoded by the ADORA1 gene. The receptor is widely expressed in the brain and heart, among other tissues, and participates in inhibitory signaling in response to extracellular adenosine.

Upon activation, A1AR couples to Gi/o proteins, inhibiting adenylate cyclase, reducing intracellular cAMP, and modulating ion channels such as GIRK. This signaling decreases neuronal excitability and can slow heart rate, contributing to protective effects during metabolic stress.

Physiological roles attributed to A1AR include regulation of sleep and arousal, modulation of synaptic transmission, anti-nociception, and neuroprotection during ischemia. It also participates in cardioprotective mechanisms by limiting cAMP-mediated processes in cardiac tissue.

Pharmacologically, selective A1AR agonists and antagonists are used in research to study receptor function. Antagonists such as DPCPX are commonly employed to block A1AR-mediated effects and to distinguish receptor-specific signaling from other adenosine receptor subtypes.

Outside of biology, a1ar may appear as a lowercase form or acronym in other contexts, such as usernames, file names, or identifiers in software and online communities. In these cases, it does not denote a single universal topic.