Lipid composition of lung and lung lavage fluid from map turtles (Malaclemys geographica) maintained at different environmental temperatures.

The phospholipids of lung and lung lavage fluid from map turtles (Malaclemys geographica) acclimated to 5, 14, 22 and 32 degrees C have been analyzed. The yield of surfactant (lavage) lipid P was higher at 32 than at 5 degrees C, but there was no significant change in lung lipid P. The relative proportions of phospholipids from the lung were PC greater than PE greater than SM greater than PS greater than PI, while those for the lavage were PC greater than PI greater than PE greater than SM congruent to PS. PC constituted 71-78% of the surfactant phospholipid over the temperature range. Small changes in the amounts of PC and PE of lung and in PC and PI of lavage were observed at different temperatures. The fatty acid compositions of the lipids from the two sources were different in many respects. The lavage lipids contained more saturated acids, especially palmitic acid, than did the lung lipids. The fatty acid compositions indicated the presence of disaturated PC in lung lavage and diunsaturated species of PC and PE in lung. The total saturated fatty acids of PC and PE in lung and of PC in surfactant increased at higher temperatures. In the surfactant PC this increase reflected principally a rise in palmitate and a drop in palmitoleate contents. The saturated PC obtained from lavage at each temperature contained more than 85% palmitic acid, indicating that the principal saturated PC was DPPC. These changes are consistent with the type of alterations in the lipid composition of membranes which occur during homeoviscous adaptation.