Reaction of No With O2−. Implications for the Action of Endothelium-Derived Relaxing Factor (EDRF)

Under physiological pH conditions (pH 7.2-7.4) the rate constant of the reaction NO + O2- yielding peroxonitrite (ONOO-) was determined as k = (3.7 +/- 1.1) x 10(7) M-1 s-1. The decay of peroxonitrite at this pH follows first order kinetics with a rate constant of 1.4 s 1. At alkaline pH peroxonitrite is practically stable. Possible consequences of these reactions for the biological lifetime of EDRF will be discussed.