Figure 7.

^•O₂⁻ generation from purified nNOS: (trace A) 50 mM Tris-HCl buffer (pH 7.4) containing 1 mM NADPH, 10 μM BH4, 0.5 mM Ca²⁺, 10 μg/ml calmodulin, 1 mM l-Arg, and nNOS (7.5 μg/ml); (trace B) as in trace A but with no l-Arg; and (trace C) with addition of SOD, 200 units/ml. EPR spectra were recorded in presence of 50 mM DMPO as described for Fig. 6, except that each is the sum of ten 1-min acquisitions.