Lysophosphatidylcholine increases airway and capillary permeability in the isolated perfused rat lung

The effects of lysophosphatidylcholine (lysoPC) on airway and capillary permeability in the isolated perfused rat lung were investigated. We determined the influence of lysoPC on the passage of different-sized (326-722 dalton) polyethylene glycols (PEGs), both from the airways to the pulmonary circulation and from the pulmonary circulation into the lung. We found that 1 mM lysoPC increased the overall passage of PEGs from the airways to the pulmonary circulation, and that 80 microM lysoPC increased the overall passage from the circulation into the lung. In both cases, the passage of the larger (502-722 dalton) PEGs increased more than the passage of the smaller (326-458 dalton) PEGs. We also found that the presence of lysoPC in the circulation increased the pulmonary arterial pressure, whereas deposition of lysoPC in the trachea did not. The pressure increase was blocked by indomethacine, BW755C, and quinacrine, inhibitors of arachidonic acid metabolism. These findings suggest that higher concentrations of lysoPC increase the airway permeability to larger molecules, and that lower concentrations of lysoPC increase the capillary permeability. The increase in capillary permeability may be due to a rise in capillary pressure mediated by arachidonic acid metabolites. The possibility that formation and accumulation of lysoPC is of importance for mediating inflammatory reactions in the lung is inferred.