DAF technique for real-time NO imaging in the human myocardium

Abstract

Nitric oxide (NO), synthesized from L-arginine by NO-synthases (NOS), is involved in the regulation of many physiological and pathophysiological mechanisms in nearly every organ system. Many of the proposed NO mediated-functions are controversially discussed because direct evidence for the involvement of NO is missing. One reason is the difficulty of NO detection. NO is a gaseous small, hydrophobic molecule with chemical properties that allow it to act as an intra- or extra-cellular messenger. Furthermore NO has a very labile nature. It exists only for a few seconds (3-10 s) before it is converted by O2 and H2O into NO2- and NO 3- or it reacts with oxygen radicals to form peroxynitrite. Before NO is eliminated it affects several target structures, e.g. soluble guanyl cyclase (sGC), ion channels and other intracellular proteins. Commonly NO reacts within cell signalling cascades and the NO signal gets amplified during this process. This implies that only a very small amount of NO is necessary to affect the target structures. This circumstance is a further problem of NO detection. © Springer-Verlag Berlin Heidelberg 2005.