Dietary sources of nitrite as a modulator of ischemia/reperfusion injury

The nitrite anion is an endogenous product of nitric oxide (NO) metabolism, a key intermediate in the nitrogen cycle in plants and bacteria, and a constituent of many foods. Research over the past 6 years has revealed a surprising biological and cytoprotective activity of this anion. Its ability to restore NO homeostasis throughout the physiological oxygen gradient in vivo has transformed this once-thought to be inert anion into a critical molecule in health and disease. Ischemia-reperfusion (I/R) injury is a major clinical problem worldwide. NO has been shown to be one of the most important molecules for the prevention of injury from I/R. Paradoxically, however, enzymatic NO formation from NO synthase (NOS) is inactive during conditions of inadequate oxygen and substrate delivery, such as in ischemia. Nitrite has emerged as a viable alternative source of NO under ischemic conditions. As nitrite is known to be derived not only from the oxidation of NO but also through diet, understanding nitrite metabolism and mechanisms of cytoprotection may offer novel and natural means to prevent disease or at least limit injury from an I/R event. Here, we review the current body of knowledge regarding dietary sources of nitrite and its modulation of cytoprotection in an I/R injury. Kidney International (2009) 75, 1140-1144; doi:10.1038/ki.2009.13; published online 11 February 2009