Experimental and theoretical investigation of arachidonic acid uptake in macrophages

The kinetics of H-3-labeled arachidonic acid (AA, 10(-10)-10(-5) M) incorpo ration into murine peritoneal macrophages was investigated. During the inco rporation of AA into the cells, the steady state was reached at 10 h. The l evel of incorporation consisted of 48-50% for nanomolar concentrations and 28-30% for micromolar concentrations of AA. Exogenous AA in micromolar but not nanomolar concentrations stimulated [H-3]AA release from intracellular stores of pre-labeled cells. A mathematical model fitting the behavior of t he experimental system is proposed. The difference in the level of uptake o f AA in nanomolar and micromolar concentrations is explained by the activat ion of AA release from intracellular stores at high concentrations of exoge nous AA.