Adenosine

Adenosine is an endogenous purine nucleoside composed of the base adenine and the sugar ribose. It occurs in all living cells and plays a central role in energy metabolism, signal transmission, and the regulation of physiological processes. Adenosine is particularly well known as a component of adenosine triphosphate (ATP), the body's universal energy currency. Yet even beyond its function in energy metabolism, adenosine acts as an important messenger – especially in the central nervous system and the cardiovascular system. As a signaling molecule, it binds to specific adenosine receptors (A1, A2A, A2B, A3), through which it exerts various effects – from calming neuronal activity to dilating blood vessels. Due to its versatile biological function, adenosine is of great importance both in basic research and in medical applications, for example in the treatment of cardiac arrhythmias or in connection with caffeine, which exerts its effect by blocking adenosine receptors.

What health benefits does adenosine offer?

Adenosine is valued primarily in the medical context for its physiological and pharmacological effects. The most important benefits that adenosine and its signaling pathways can offer are:

  • Heart protection and regulation of heart rhythm: In cardiology, adenosine is used to treat certain supraventricular tachycardias (cardiac arrhythmias), as it can briefly interrupt the conduction of impulses in the heart (1,2,3,4,5).
  • Vasodilation: Adenosine can contribute to the dilation of blood vessels, which improves blood flow and is used in coronary imaging, among other applications (4,6).
  • Inflammation inhibition & immune modulation: Depending on the receptor type, adenosine can activate anti-inflammatory signaling pathways and thus contribute to immune regulation – a potential starting point for therapeutic applications in chronic inflammation (7,8,9).
  • Calming the nervous system: Adenosine acts in the brain as a natural calming agent by dampening neuronal activity. This promotes sleep, reduces stress, and may protect against neuronal overstimulation (10,11).

How does adenosine work in the body?

Adenosine acts via four known adenosine receptors (A1, A2A, A2B, A3), which are distributed differently across various tissues. These receptors are involved in numerous physiological processes (1–11):

  • A1 receptors: Inhibit the release of neurotransmitters and slow the heart rate.
  • A2A receptors: Promote vasodilation and have anti-inflammatory effects.
  • A2B receptors: Involvement in inflammatory processes, particularly in the gut.
  • A3 receptors: Complex effects, including in the area of immune responses and apoptosis (cell death).

Adenosine is produced in the body through the breakdown of ATP, among other pathways, especially during energy demand, stress, physical exertion, or oxygen deficiency. It acts locally, as it is very short-lived in the blood – a property that is utilized for its rapid but short-lasting effect in emergency medicine.

Are there any risks or side effects?

  • Cardiovascular reactions: With medical use of adenosine (e.g., as an injection), severe bradycardia (slow heartbeat), a drop in blood pressure, or shortness of breath can occur briefly – this is medically intended but must be monitored.
  • Interaction with caffeine: Caffeine blocks the action of adenosine receptors in the brain, thereby preventing the calming effect – one reason for the stimulating effect of coffee.
  • Not suitable for long-term use: Adenosine is used in emergency medicine, but not for chronic applications, as the receptors can develop reduced sensitivity with repeated stimulation (desensitization).

Conclusion Adenosine is a highly potent endogenous molecule of central importance in energy metabolism, cell communication, and the regulation of numerous physiological processes. It has a calming effect on the nervous system, regulates heart rhythm, promotes blood circulation, and has anti-inflammatory effects. Due to its short half-life and specific receptor binding, adenosine also holds an important place in emergency medicine.

Sources:

  1. Bulluck, H., Sirker, A., Loke, Y. K., Garcia-Dorado, D., & Hausenloy, D. J. (2016). Clinical benefit of adenosine as an adjunct to reperfusion in ST-elevation myocardial infarction patients: An updated meta-analysis of randomized controlled trials. International journal of cardiology, 202, 228–237. https://doi.org/10.1016/j.ijcard.2015.09.005
  2. Kitakaze, M. et al. (1993). Cardioprotective Actions of Adenosine in the Heart: New Strategy for the Treatment of Ischemic Heart Diseases. In: Maruyama, Y., Kajiya, F., Hoffman, J.I.E., Spaan, J.A.E. (eds) Recent Advances in Coronary Circulation. Springer, Tokyo. https://doi.org/10.1007/978-4-431-68249-3_29
  3. Liang, B. T., & Jacobson, K. A. (1999). Adenosine and ischemic preconditioning. Current pharmaceutical design, 5(12), 1029–1041.
  4. Hori, M., & Kitakaze, M. (1991). Adenosine, the heart, and coronary circulation. Hypertension, 18(5), 565–574. https://doi.org/10.1161/01.HYP.18.5.565
  5. DiMarco, J. P., Miles, W., Akhtar, M., Milstein, S., Sharma, A. D., Platia, E., McGovern, B., Scheinman, M. M., & Govier, W. C. (1990). Adenosine for paroxysmal supraventricular tachycardia: dose ranging and comparison with verapamil. Assessment in placebo-controlled, multicenter trials. The Adenosine for PSVT Study Group. Annals of internal medicine, 113(2), 104–110. https://doi.org/10.7326/0003-4819-113-2-104
  6. Layland, J., Carrick, D., Lee, M., Oldroyd, K., & Berry, C. (2014). Adenosine: Physiology, pharmacology, and clinical applications. JACC: Cardiovascular Interventions, 7(6), 581–591. https://doi.org/10.1016/j.jcin.2014.02.009
  7. Cronstein B. N. (1994). Adenosine, an endogenous anti-inflammatory agent. Journal of applied physiology (Bethesda, Md. : 1985), 76(1), 5–13. https://doi.org/10.1152/jappl.1994.76.1.5
  8. Kohno, K., Ohashi, E., Sano, O. et al. Anti-inflammatory effects of adenosine N1-oxide. J Inflamm 12, 2 (2015). https://doi.org/10.1186/s12950-014-0045-0
  9. Huang X, Zhao W, Mills T, Shi L and Yuan X (2025) Editorial: Immunoregulation by adenosine signaling in infection and inflammation. Front. Cell Dev. Biol. 13:1586379. doi: 10.3389/fcell.2025.1586379
  10. Dunwiddie, T. V., & Masino, S. A. (2001). The role and regulation of adenosine in the central nervous system. Annual review of neuroscience, 24, 31–55. https://doi.org/10.1146/annurev.neuro.24.1.31
  11. Ribeiro, J. A., Sebastião, A. M., & de Mendonça, A. (2002). Adenosine receptors in the nervous system: Pathophysiological implications. Progress in Neurobiology, 68(6), 377–392.[ https://doi.org/10.1016/S0301-0082(02)00155-7