Uptake of the Phospholipase A2 Inhibitor 1-Dodecyl 2-[L-14q Octanamido-Sn-2-Deoxy Glycero-3-Phosphocholine by Peritoneal Macrophages

The [14C] phospholipid analogue l-dodecyl-2-[l-14C] octanamido-sn-2-deoxy glycero-3-phosphocholine was synthetized. With 2 short fatty chains linked by alkyl and amido bonds to positions 1 and 2 of the glycerophosphate backbone, it was an inhibitor of phospholipase A2 in ionophore A23187-stimulated macrophages. Its uptake by rat peritoneal macrophages and its resistance towards phospholipases A2 were determined at nanomolar or micromolar concentrations in the culture medium. A control substrate for phospholipases A2 activity was established with the lecithin 1-octadecanoyl 2-[3H] eicosatetraenoyl-sn-glycero-3-phosphocholine ([3H] 20:4-GPC), a source of [3H] arachidonic acid after cleavage at position 2.Non-stimulated-or ionophore A23187-stimulated macrophages incorporated extensively the [I4C] phospholipid analogue added at 30-4000 nM. At 4000 nM which induced 50% inhibition of the phospholipase, 40% of the dose was found associated with the [I4C] phospholipids of 2 ×106 stimulated macrophages after 120 min incubation, while only low amounts of [I4C] non-phosphorous lipids were detected. It is concluded that the [14C] phospholipid analogue was readily taken up by the macrophages with limited hydrolysis.