AICA ribonucleotide explained

5-Aminoimidazole-4-carboxamide ribonucleotide (AICAR) is an intermediate in the generation of inosine monophosphate. AICAR is an analog of adenosine monophosphate (AMP) that is capable of stimulating AMP-dependent protein kinase (AMPK) activity. The drug has also been shown as a potential treatment for diabetes by increasing the metabolic activity of tissues by changing the physical composition of muscle.[1]

Mechanism of action

The nucleoside form of AICAR, acadesine, is an analog of adenosine that enters cardiac cells to inhibit adenosine kinase and adenosine deaminase. It enhances the rate of nucleotide re-synthesis increasing adenosine generation from adenosine monophosphate only during conditions of myocardial ischemia.[2] In cardiac myocytes, acadesine is phosphorylated to AICAR to activate AMPK without changing the levels of the nucleotides.[3] AICAR is able to enter the de novo synthesis pathway for adenosine synthesis to inhibit adenosine deaminase causing an increase in ATP levels and adenosine levels.[4]

Use as a performance-enhancing drug

In 2009, the French Anti-Doping Agency, suspected that AICAR had been used in the 2009 Tour de France for its supposed performance enhancing properties.[5] [6] Although a detection method was reportedly given to the World Anti-Doping Agency, it was unknown if this method was implemented.[7] As of January 2011, AICAR was officially a banned substance in the World Anti Doping Code,[8] and the standard levels in elite athletes have been determined, to interpret test results.[9] [10]

See also

Notes and References

  1. News: Zarembo. Alan. 1 August 2008. 'Exercise pill' could take the work out of workouts. Los Angeles Times. 21 January 2012.
  2. Kristiansen. Steen B.. Solskov. Lasse. Jessen. Niels. Løfgren. Bo. Schmitz. Ole. Nielsen-Kudsk. Jens Erik. Nielsen. Torsten T.. Bøtker. Hans Erik. Lund. Sten. 2009. 5-Aminoimidazole-4-carboxamide-1-β-D-ribofuranoside increases myocardial glucose uptake during reperfusion and induces late pre-conditioning: Potential role of AMP-activated protein kinase. Basic & Clinical Pharmacology & Toxicology. 105. 1. 10–16. 10.1111/j.1742-7843.2009.00402.x. free. 19486332. 3062525. free.
  3. Zhang. Li. Frederich. Markus. He. Huamei. Balschi. James A.. 2006. Relationship between 5-aminoimidazole-4-carboxamide-ribotide and AMP-activated protein kinase activity in the perfused mouse heart. American Journal of Physiology. Heart and Circulatory Physiology. 290. 3. H1235–H1243. 10.1152/ajpheart.00906.2005. 16258030. 18273128. free.
  4. Longnus. Sarah L.. Wambolt. Richard B.. Parsons. Hannah L.. Brownsey. Roger W.. Allard. Michael F.. 2003. 5-Aminoimidazole-4-carboxamide 1-β-D-ribofuranoside (AICAR) stimulates myocardial glycogenolysis by allosteric mechanisms. American Journal of Physiology. Regulatory, Integrative and Comparative Physiology. 284. 4. R936–R944. 10.1152/ajpregu.00319.2002. 12626360. 19608127. free.
  5. News: Cooke. Nicole. 11 March 2015. Nicole Cooke: CIRC report is admirable but authorities must do more on drugs. The Guardian. 13 March 2015. There will always be new drugs, such as the weight-loss drug Aicar, which enables riders to shed up to 7kg and yet still maintain their power output. Obviously, it takes time to develop tests for these but it needs to be agreed that retrospective testing can secure sanctions..
  6. News: Niiler. Eric. 10 March 2015. Doping spreading to amateur cyclists: Report. Seeker. 13 March 2015. The commission, formed in 2013 by the sport's governing body, interviewed 174 experts, riders, doctors and team officials. It found a flood of new substances or methods used to enhance blood oxygen capacity include Aicar, Xenon gas, ozone therapy, ITPP, Gas6, Actovegin, various forms of EPO such as CERA, 'Eprex', EPO zeta, EPO Retacrit, Neorecormon, and Albumina. Most of these are used to help patients with severe anemia or blood disorders..
  7. News: Simms. Daniel. 27 July 2009. AFLD president suspects new drugs in peloton. Cyclingnews. 17 March 2012.
  8. News: . 20 December 2010. Important changes made to the World Anti-Doping Code. Cyclingnews. 17 March 2012.
  9. Thomas. Andreas. Beuck. Simon. Eickhoff. Jens Christian. Guddat. Sven. Krug. Oliver. Kamber. Matthias. Schänzer. Wilhelm. Thevis. Mario. 2010. Quantification of urinary AICAR concentrations as a matter of doping controls. Analytical and Bioanalytical Chemistry. 396. 8. 2899–2908. 10.1007/s00216-010-3560-8. 20225061. 25220894.
  10. Web site: Report to the President of the Union Cycliste Internationale. Cycling Independent Reform Commission. February 2015. Union Cycliste Inernationale. https://web.archive.org/web/20150318233857/http://www.uci.ch/mm/Document/News/CleanSport/16/87/99/CIRCReport2015_Neutral.pdf. 18 March 2015. The core elements to achieve performance enhancement through doping in cycling have remained the same over the years: firstly, increasing the blood's oxygen carrying capacity, and, secondly, stimulating muscle growth and aiding muscle recovery. Over the years riders have adapted the substances and methods used to achieve these goals in response to: (i) the type of substances available and accessible on the pharmaceutical market (e.g., various EPO generations); (ii) specific drug detection capabilities of laboratories, (e.g., the switch from EPO to blood transfusions or to ozone therapy, or even towards the so-called 'oxygen in a pill' in the form of GW1516 and AICAR); and (iii) other anti-doping tools, such as the ABP which has led to micro-dosing (see below).. 57.

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