Fig. 4.

Nitric oxide production by nitrite and red blood cells. Deoxygenated RBCs (50% Hct, 100 µL) were injected into 20 ml of PBS (pH 6.8) containing 20 mM nitrite in a three neck round bottom flask that was connected directly to a chemiluminescence-based nitric oxide analyzer with and without illumination by far red light (660 nm, 65 mW). Data are plotted as mean ± one standard error. (A) Representative raw data from the nitric oxide analyzer. RBCs were injected at 5 min and the signal increases more with light than without (indicated by arrow). (B) Average areas of the signals showing greater NO production in the presence of light (P = 0.04, n = 8).