Experimental and Theoretical Investigation of Arachidonic Acid Uptake in Macrophages

The kinetics of ³H-labeled arachidonic acid (AA, 10^—10-10^—5 M) incorporation into murine peritoneal macrophages was investigated. During the incorporation of AA into the cells, the steady state was reached at 10 h. The level 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 [³H]AA release from intracellular stores of pre-labeled cells. A mathematical model fitting the behavior of the experimental system is proposed. The difference in the level of uptake of AA in nanomolar and micromolar concentrations is explained by the activation of AA release from intracellular stores at high concentrations of exogenous AA.