Disruption of phospholipid metabolism by paraquat in cultured pneumocytes.

Paraquat (PQ) has specific pneumotoxicity in humans. Its effects on phospholipid metabolism in type 2 pneumocytes, A-549, and in lung fibroblasts, WI-38, were examined. PQ inhibited the incorporation of palmitic acid into phosphatidyl-ethanolamine by 42%, but did not inhibit the incorporation into phosphatidylcholine. PQ also inhibited the incorporation of acetate into phosphatidylcholine and ethanolamine by 82-88% in A-549 cells and by 92% in WI-38 cells. PQ inhibited the incorporation of choline into phosphatidylcholine and ethanolamine by 55 and 73%, respectively. Phosphatidylcholine was detected in the medium of A-549 cells. PQ completely inhibited this phosphatidylcholine secretion. These results suggest that PQ has inhibitory effects on phospholipid synthesis and excretion in human type 2 pneumocytes.