The influence of serum fatty acid binding proteins on arachidonic acid uptake by macrophages

The role of serum fatty acid binding proteins (FABPs) in arachidonic acid ( AA) uptake by murine peritoneal macrophages has been studied. The kinetics of [H-3]arachidonic acid uptake by the cells was investigated over a wide r ange of AA concentration (10(-10)-10(-5) M). It was shown that these putati ve fatty acid transporters dramatically change the uptake processes. In the presence of FABPs, the time-course curves of AA uptake exhibited two disti nct periods: one with a rapid AA uptake during the first hour with an equil ibrium in 1-2.5 h and another with an equilibrium reached in 20 h, whereas in the absence of FABPs the uptake curves were smooth without kinks and wit h the equilibrium reached in 10 h. In addition, it was shown that the amoun t of incorporated AA was Linearly dependent on the concentration of AA over the range of 10(-10)-10(-6) M in the presence of serum FABPs and 10(-10)-1 0(-7) M in their absence. We assume that the changes in the character of AA uptake by macrophages in the presence of FABPs occur due to the interaction of FABPs with the cell p lasma membrane.