Phospholipase A2-evoked destabilization of planar lipid membranes.

The ability of phospholipase A2 (PLA2) to enhance the flux of charged molecules across a planar lipid bilayer was examined. Within 300 s of adding PLA2, the membrane destabilized, with transient currents and eventual failure of membrane integrity. This effect was blocked by removal of free Ca2+ (with EGTA) or by substitution of normal phospholipids with non-substrate lipids, indicating specificity of PLA2 activity. PLA2 may similarly destabilize plasma membranes, allowing for the movement of molecules down their concentration gradients. PLA2, which is activated by cerebral ischemia, could thus contribute to the extracellular accumulation of neurotoxic excitatory amino acids.