Phosphatidylglycerol in rat lung. I. Identification as a metabolically active phospholipid in isolated perfused rat lung

Isolated rat lungs when perfused for 2 hr with [U-14]glucose, [2-14C]lactate, or [u-14]acetate, were found to contain a phos pholipid which represented a small percentage of the total phospholipid (3.9 per cent), and possessed the highest specific activity of any phospholipid. Using chromatographic, chemical, and mass spectral analysis, the phospholipid has been identified as phosphatidylglyercol. When [2-14C]lactate was present in the perfusion medium, 15.3 per cent of the lactate incorporated into phospholipids was incorporated into phosphatidylglyerol with a relative specific activity of 5.1 compared to phosphatidylcholine, 1.0, and phosphatidylethanolamine, 0.5. Phosphatidylglycerol also had the highest specific activity when lungs were perfused with [1-14C]acetate and [U-14]glucose. While the significance of the content and apparent metabolic activity of phosphatidylglycerol are unknown, its possible role in stabilizing the surfactant complex of lung is discussed.