KINETICS OF NITRIC-OXIDE AUTOXIDATION IN AQUEOUS-SOLUTION

A kinetic study of the reaction of NO with O-2 in aqueous solution has been carried out using a colorimetric method based on a pH indicator and a stopped-flow spectrophotometer. The reaction is second order in NO concentration and first order in O-2 concentration; the overall thi rd order rate constant is 6.3 (+/- 0.4) x 10(6) (M(-1))(2) s(-1). Mode l calculations for the reaction at estimated physiological concentrati ons of NO and O-2 indicate that the simple autoxidation of NO will not limit its diffusion from the site of production in endothelial cells to a spatially removed target molecule such as guanylate cyclase in my ocytes and platelets.