ESTIMATION OF NITRIC-OXIDE PRODUCTION AND REACTION-RATES IN TISSUE BYUSE OF A MATHEMATICAL-MODEL

Nitric oxide (NO) produced by the vascular endothelium is an important biologic messenger that regulates vessel tone and permeability and in hibits platelet adhesion and aggregation. NO exerts its control of ves sel tone by interacting with guanylyl cyclase in the vascular smooth m uscle to initiate a series of reactions that lead to vessel dilation. Previous efforts to investigate this interaction by mathematical model ing of NO diffusion and reaction have been hampered by the lack of inf ormation on the production and degradation rate of NO. We use a mathem atical model and previously published experimental data to estimate th e rate of NO production, 6.8 x 10(-14) mu mol.mu m(-2).s(-1); the NO d iffusion coefficient, 3,300 mu m(2) s(-1); and the NO consumption rate coefficient in the vascular smooth muscle, 0.01 s(-1) (Ist-order rate expression) or 0.05 mu M-1.s(-1) (2nd-order rate expression). The mod eling approach is discussed in detail. It provides a general framework for modeling the NO produced from the endothelium and for estimating relevant physical parameters.