Plasma Nitrite and Nitrate Determination

The concentrations of nitrite and nitrate in blood plasma are important in clinical situations, because they are now known to be the spontaneous chemical products of nitric oxide (NO) in blood (1 ). NO is a mediator with numerous functions, including the regulation of vascular tone (2 ) and cell-to-cell communication (3 ). It is also thought to be one of the chief pathogenic factors causing shock and organ dysfunction seen in critically ill patients (4 ). Because NO is rapidly oxidized to nitrite and nitrate in blood, these are used as the markers of NO generation.