Effect of choline deficiency on lung phospholipid concentrations in the rat

Lung surfactant and nonsurfactant phospholipid concentrations were analyzed in relation to choline status in male rats fed a choline-deficient (CD) or choline-supplemented (CS) diet over an 8-d period. On the first day plasma choline concentrations were significantly lower (11.5 +/- 0.9 micron) in rats fed the CD diet than in those fed the CS diet (16.1 +/- 1.2 microM). This relationship continued for the duration of the study. Hepatic phosphatidylcholine/phosphatidylethanolamine (PC/PE) ratios were significantly lower after d 1 of the CD diet, further decreased on d 2 (1.09 +/- 0.04) and remained low through d 8. Only on d 4 were lung surfactant PC and total phospholipid concentrations lower in rats fed the CD diet than in those fed the CS diet. The composition of surfactant, determined by the ratio of PC to total phospholipids, did not change. On both d 4 and d 8 the PC/PE ratios in the nonsurfactant fraction were lower in rats fed the CD diet than in those fed the CS diet. This shift in PC/PE ratio in the lung is similar to the PC/PE shift in the liver associated with dietary choline deficiency. The altered lung phospholipid concentrations in the nonsurfactant (residual) fraction on d 4 and d 8 suggest an adaptation in the lung's phospholipid metabolism to replenish the physiologically essential surfactant PC.