KATP open-channel time and frequency. Sports doping Inhaling a xenon/oxygen mixture activates production of the transcription factor HIF-1-alpha, which may lead to increased production of erythropoietin. The latter hormone is known to increase red blood cell production and athletic performance. Reportedly, doping with xenon inhalation has been used in Russia since 2004 and perhaps earlier. On August 31, 2014, the World Anti Doping Agency (WADA) added xenon (and argon) to the list of prohibited substances and methods, although no reliable doping tests for these gases have yet been developed. In addition, effects of xenon on erythropoietin production in humans have not been demonstrated, so far. Imaging Gamma emission from the radioisotope 133Xe of xenon can be used to image the heart, lungs, and brain, for example, by means of single photon emission computed tomography. 133Xe has also been used to measure blood flow. Xenon, particularly hyperpolarized 129Xe, is a useful contrast agent for magnetic resonance imaging (MRI). In the gas phase, it can image cavities in a porous sample, alveoli in lungs, or the flow of gases within the lungs. Because xenon is soluble both in water and in hydrophobic solvents, it can image various soft living tissues. Xenon-129 is currently being used as a visualization agent in MRI scans. When a patient inhales hyperpolarized xenon-129 ventilation and gas exchange in the lungs can be imaged and quantified. Unlike xenon-133, xenon-129 is non-ionizing and is safe to be inhaled with no adverse effects. Surgery The xenon chloride excimer laser has certain dermatological uses. NMR spectroscopy Because of the xenon atom's large, flexible outer electron shell, the NMR spectrum changes in response to surrounding conditions and can be used to monitor the surrounding chemical circumstances. For instance, xenon dissolved in water, xenon dissolved in hydrophobic solvent, and xenon associated with certain proteins can be distinguished by NMR. Hyperpolarized xenon can be used by surface chemists. Normally, it is difficult to characterize surfaces with NMR because signals from a surface are overwhelmed by signals from the atomic nuclei in the bulk of the sample, which are much more numerous than surface nuclei. However, nuclear spins on solid surfaces can be selectively polarized by transferring spin polarization to them from hyperpolarized xenon gas. This makes the surface signals strong enough to measure and distinguish from bulk signals. Other In nuclear energy studies, xenon is used in bubble chambers, probes, and in other areas