Adenosine-15N5 (Adenine riboside-15N5; D-Adenosine-15N5) is a form of adenosine labeled with the nitrogen isotope 15N. This compound, also known as adenosine (adenine riboside), is a prevalent endogenous secretion that exerts its effects through four G protein-coupled receptors (A1, A2A, A2B, and A3). Adenosine influences nearly every aspect of cellular physiology, including neuronal activity, vascular function, platelet aggregation, and the regulation of blood cells.