Surfactant dysfunction in diabetic offspring: inhibitors and fatty acid lecithin content.

We have previously demonstrated that the lungs of fetuses of alloxan-diabetic rabbits are functionally immature when compared with controls. In this study we have examined pulmonary lavage fluid from fetuses of diabetic and control does for the presence of a surfactant inhibitor, cholesterol content, and phosphatidylcholine (lecithin) fatty acid content. When lavage fluids from fetuses of control and diabetic does were mixed and examined on the surface balance, the measured surfactant content corresponded to the arithmetic average of the surfactant content of the individual fluids, thus ruling out the presence of an excess of a surfactant inhibitor. We were able to demonstrate inhibition of surfactant function when exogenous cholesterol was added to lavage samples, but cholesterol content of lavage fluid from fetuses of diabetic and control does was not significantly different. Finally, the fatty acid composition of surfactant phosphatidylcholine was not different between the two groups. These studies indicate that mechanisms other than the presence of a surfactant inhibitor or altered fatty acid composition must explain the functional immaturity seen in offspring of the diabetic pregnancy.