| Summary: | An investigation of the effect of change of total CO2 concentration from 7 to 43 mM at pH 7.35 in the medium perfusing isolated rat lungs on [U-14C]glucose incorporation into lung phospholipids has been carried out. The incorporation of [U-14C]glucose into phosphatidylcholine and phosphatidylglycerol of the surfactant fraction and of the remaining lung tissue (residual fraction) was observed. Increased CO2 concentration increased [U-14C]glucose incorporation into phosphatidylcholine of the surfactant fraction and residual fraction by 43 and 50%, respectively, during a 2 hr perfusion. Likewise, incorporation of [U-14C]glucose into phosphatidylglycerol was increased 22 and 34% into the surfactant and residual fractions, respectively. The percentage of [U-14C]glucose incorporated into the fatty acid moieties of phosphatidylcholine of both fractions increased as a result of increased CO2 concentration. The increase in the incorporation of [U-14C]glucose into the fatty acid moieties of phosphatidylcholine was confirmed by an average increase of 56 and 77% in the specific activity of palmitic acid isolated from phosphatidylcholine of the surfactant and residual fraction, respectively, as a result of increased CO2 concentration. The results suggest that alteration in extracellular CO2 concentration affects the de novo synthesis from glucose of phosphatidylcholine and phosphatidylglycerol of the surfactant-lipoprotein fraction of lung.
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