Fig. 3. Distribution and kinetics of accumulation of nitric oxide metabolites in mice breathing nitric oxide (heart, lung, brain, and liver). Concentrations of nitric oxide metabolites were measured in tissues of mice breathing air supplemented with nitric oxide for 0, 0.5, 5, 15, and 60 min (n = 4–7). NO-heme = nitrosyl-heme species; RNNO = N -nitrosamines; RSNO = S -nitrosothiols. Additional information regarding each concentration, the number of animals studied, and the P value are available on the Anesthesiology Web site at http://www.anesthesiology.org, in Web Enhancement 3–table 2.