Role of intracellular glycerol-3-phosphate in the synthesis of phosphatidylglycerol by freshly isolated adult rat alveolar type II cells.

Synthesis of phosphatidylglycerol and phosphatidylinositol, phospholipid components of pulmonary surfactant, use the same precursor, CDP-diacylglycerol. In alveolar type II epithelial cells, extracellular myoinositol has been used to suppress phosphatidylglycerol synthesis, presumably by competing with glycerol-3-P for a common pool of CDP-diacylglycerol. We sought to see if extracellular lactate would increase acetate incorporation into phosphatidylglycerol by increasing glycerol-3-P. Lactate and 10 mM cytidine increased acetate incorporation into phosphatidylglycerol, whereas myoinositol and pyruvate decreased acetate incorporation into phosphatidylglycerol. Lactate increased the intracellular content of glycerol-3-P. We conclude that phosphatidylglycerol synthesis can, in part, be regulated by intracellular glycerol-3-P concentration, and we speculate that extracellular (alveolar) lactate may increase glycerol-3-P concentration in alveolar type II cells in vivo.