Nitric oxide scavenging and oxidizing potential of plasma from sph/sph mice is greater than that of plasma from normal (+/+, sph/+) mice. (A) Helium EPR measurements of plasma metHb levels before (□) and after () the addition of the NO donor proline/NO. Data are presented as mean (± SEM) for n = 3 +/+, n = 5 sph/+, and n = 4 sph/sph mice. All mice were between 6 and 9 weeks of age. *P < .02 compared with +/+ or sph/+plasma with proline/NO added. (B) Oxygen uptake assay of oxidizing potential of plasma from normal (+/+, □) and sph/sph (■) mice. Data presented as mean (± SEM) for n = 4 mice per group. Mice in both groups were between 7 and 13 weeks of age; there were no differences between data from younger versus older mice. *P < .013 compared with +/+ plasma.